thromboxane-b2 and Ischemia

Topics: Asthma; Biomarkers; Cardiovascular Diseases; Humans; Immunoenzyme Techniques; Ischemia; Kidney Failure, Chronic; Radioimmunoassay; Reference Values; Specimen Handling; Thrombosis; Thromboxane A2; Thromboxane B2

Platelets critically contribute to atherothrombosis and worsening ischaemia in patients with peripheral arterial disease (PAD), eventually leading to critical limb ischaemia (CLI). Furthermore, persistent platelet activation despite antiplatelet therapy has been reported in this setting. The prostacyclin analogue iloprost is currently recommended in CLI patients for its effects in relieving symptoms by promoting local perfusion. In this study, we investigated the effects of iloprost infusion on urinary 11-dehydro-TXB₂ and 8-iso-PGF(₂α) excretion rate, as in vivo indexes of thromboxane-dependent platelet activation and lipid peroxidation, respectively, and on platelet-derived proinflammatory sCD40L and nitric oxide bioavailability in 44 patients with CLI while on chronic treatment with low-dose aspirin. Daily iloprost infusion for one-week significantly decreased urinary 11-dehydro-TXB₂ [499 (277-807) vs. 380 (189-560) pg/mg creatinine, p < 0.0001] and 8-iso-PGF(₂α) [533 (316-842) vs. 334 (196-540) pg/mg creatinine, p < 0.0001] as well as plasma sCD40L [1540 (1005-3015) vs. 948 (845-2030) pg/ml, p < 0.0001]. Furthermore, a significant increase in plasma nitrate plus nitrite levels has been observed [26.8 (18.8-35.9) vs. 43.7 (33.0-75.5) μM, p < 0.0001]. A significant direct correlation was also found between urinary 8-iso-PGF(₂α) and 11-dehydro-TXB2 before and after iloprost treatment (Rho = 0.695, p < 0.0001). In conclusion, we report that a short-term course of iloprost is able to significantly reduce residual thromboxane biosynthesis, oxidative stress, endothelial dysfunction and platelet-derived inflammation in low-dose aspirin treated patients with CLI.

Topics: Aged; Aged, 80 and over; Aspirin; Biomarkers; Blood Platelets; CD40 Ligand; Chi-Square Distribution; Critical Illness; Dinoprost; Drug Administration Schedule; Female; Humans; Iloprost; Inflammation Mediators; Infusions, Intravenous; Ischemia; Italy; Lipid Peroxidation; Male; Middle Aged; Nitric Oxide; Oxidative Stress; Platelet Activation; Platelet Aggregation Inhibitors; Thromboxane B2; Time Factors; Treatment Outcome

During exercise, muscle mechanoreflex-mediated sympathoexcitation evokes renal vasoconstriction. Animal studies suggest that prostaglandins generated within the contracting muscle sensitize muscle mechanoreflexes. Thus we hypothesized that local prostaglandin blockade would attenuate renal vasoconstriction during ischemic muscle stretch. Eleven healthy subjects performed static handgrip before and after local prostaglandin blockade (6 mg ketorolac tromethamine infused into the exercising forearm) via Bier block. Renal blood flow velocity (RBV; Duplex Ultrasound), mean arterial pressure (MAP; Finapres), and heart rate (HR; ECG) were obtained during handgrip, post-handgrip muscle ischemia (PHGMI) followed by PHGMI with passive forearm muscle stretch (PHGMI + stretch). Renal vascular resistance (RVR, calculated as MAP/RBV) was increased from baseline during all paradigms except during PHGMI + stretch after the ketorolac Bier block trial where RVR did not change from baseline. Before Bier block, RVR rose more during PHGMI + stretch than during PHGMI alone (P < .01). Similar results were found after a saline Bier block trial (Delta53 +/- 13% vs. Delta35 +/- 10%; P < 0.01). However, after ketorolac Bier block, RVR was not greater during PHGMI + stretch than during PHGMI alone [Delta39 +/- 8% vs. Delta40 +/- 12%; P = not significant (NS)]. HR and MAP responses were similar during PHGMI and PHGMI + stretch (P = NS). Passive muscle stretch during ischemia augments renal vasoconstriction, suggesting that ischemia sensitizes mechanically sensitive afferents. Inhibition of prostaglandin synthesis eliminates this mechanoreceptor sensitization-mediated constrictor responses. Thus mechanoreceptor sensitization in humans is linked to the production of prostaglandins.

Topics: Adult; Anti-Inflammatory Agents, Non-Steroidal; Blood Flow Velocity; Blood Pressure; Electrocardiography; Exercise; Female; Forearm; Hand Strength; Heart Rate; Humans; Infusions, Intravenous; Ischemia; Ketorolac Tromethamine; Kidney; Male; Mechanotransduction, Cellular; Muscle Fatigue; Muscle Spindles; Muscle, Skeletal; Neural Pathways; Prostaglandins; Reflex, Stretch; Renal Circulation; Thromboxane B2; Ultrasonography, Doppler, Duplex; Vascular Resistance; Vasoconstriction

Passive muscle stretch performed during a period of post-exercise muscle ischemia (PEMI) increases muscle sympathetic nerve activity (MSNA), and this suggests that the muscle metabolites may sensitize mechanoreceptors in healthy humans. However, the responsible substance(s) has not been studied thoroughly in humans. Human and animal studies suggest that cyclooxygenase products sensitize muscle mechanoreceptors. Thus we hypothesized that local cyclooxygenase inhibition in exercising muscles could attenuate MSNA responses to passive muscle stretch during PEMI. Blood pressure (Finapres), heart rate, and MSNA (microneurography) responses to passive muscle stretch were assessed in 13 young healthy subjects during PEMI before and after cyclooxygenase inhibition, which was accomplished by a local infusion of 6 mg ketorolac tromethamine in saline via Bier block. In the second experiment, the same amount of saline was infused via the Bier block. Ketorolac Bier block decreased prostaglandin synthesis to approximately 34% of the baseline. Before ketorolac Bier block, passive muscle stretch evoked significant increases in MSNA (P < 0.005) and mean arterial blood pressure (P < 0.02). After ketorolac Bier block, passive muscle stretch did not evoke significant responses in MSNA (P = 0.11) or mean arterial blood pressure (P = 0.83). Saline Bier block had no effect on the MSNA or blood pressure response to ischemic stretch. These observations indicate that cyclooxygenase inhibition attenuates MSNA responses seen during PEMI and suggest that cyclooxygenase products sensitize the muscle mechanoreceptors.

Topics: Adult; Blood Pressure; Cyclooxygenase Inhibitors; Exercise; Female; Hand Strength; Heart Rate; Humans; Infusions, Parenteral; Ischemia; Ketorolac Tromethamine; Male; Muscle Spindles; Muscle, Skeletal; Prostaglandins; Reflex, Stretch; Sympathetic Nervous System; Thromboxane B2

To evaluate the rate of thromboxane biosynthesis in patients with systemic lupus erythematosus (SLE), exploring the interplay between antiphospholipid antibodies (aPL) and 2 markers of endothelial perturbation: thrombin generation and platelet activation.. A comparison of 11-dehydrothromboxane B2 (TXB2) excretion, which is a marker of in vivo platelet activation, aPL, von Willebrand factor (vWF) and tissue plasminogen activator (tPA), which are 2 circulating markers of endothelial perturbation, and plasma levels of the prothrombin fragment F1+2, which is a marker of thrombin generation, was performed in 40 SLE patients and 40 healthy subjects. Thromboxane metabolite excretion was also measured in 8 SLE patients before and after treatment with low-dose aspirin.. SLE patients had significantly higher 11-dehydro-TXB2 excretion, plasma F1+2, vWF, and tPA levels than controls. A statistically significant correlation was found between plasma levels of vWF and tPA and excretion of thromboxane metabolite. Moreover, significantly higher 11-dehydro-TXB2 was found in patients with aPL positivity and endothelial perturbation. Low-dose aspirin suppressed 11-dehydro-TXB2 by 80%, suggesting a predominant platelet source of enhanced thromboxane biosynthesis. After a median followup of 48 months, all SLE patients who experienced major cardiovascular events had thromboxane metabolite excretion, aPL positivity, and signs of endothelial perturbation.. We have characterized a sensitive marker of platelet activation, which is abnormal in SLE patients who were positive for aPL and endothelial perturbation. This analytical approach may help identify those patients at increased risk of thrombosis as potential candidates for antiplatelet therapy.

Topics: Adult; Antibodies, Antiphospholipid; Antigens; Aspirin; Cross-Sectional Studies; Dose-Response Relationship, Drug; Female; Humans; Ischemia; Lupus Erythematosus, Systemic; Male; Middle Aged; Myocardial Infarction; Stroke; Thromboxane B2; Thromboxanes; Tissue Plasminogen Activator; Venous Thrombosis; von Willebrand Factor

To evaluate tissue protection by PGE1 during leg ischemia in patients undergoing aortic surgery.. Randomized, controlled prospective clinical trial.. Single university hospital.. 19 consecutive patients undergoing abdominal aortic aneurysm repair.. Patients received infusions of 30 ng/kg/min of PGE1 or saline.. Hemodynamic variables, lactate, creatine phosphokinase, and thromboxane B2 (TXB2) were measured. In the control group, the decrease in cardiac index (CI) after aortic cross-clamping (AXC) persisted until unclamping together with a decrease in femoral venous O2 content (CfvO2). In the PGE1 group, CI returned to baseline with a trend toward greater CfvO2 levels. During reperfusion in the PGE1 group, O2 consumption and lactate levels exceeded preclamp values. Pulmonary hypertension occurred equally in both groups but did not correlate with TXB2, which was not altered by surgery or by PGE1 infusion.. Intraoperative PGE1 treatment offers no benefit and may exacerbate tissue ischemia during AXC by redistributing microcirculatory flow or limiting cellular oxygen utilization in a manner that overwhelms any possible protective effect.

Topics: Aged; Alprostadil; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Female; Hemodynamics; Humans; Ischemia; Male; Middle Aged; Oxygen; Oxygen Consumption; Prospective Studies; Thromboxane B2

The ability of the imidazole derivative, ketoconazole, to inhibit thromboxane (Tx)A2 synthesis in response to ischemia was tested in ten volunteers. Two hours after taking placebo or ketoconazole 400 mg by mouth, plasma levels of the stable degradation product of TxA2, TxB2, were 300 +/- 129 pg/ml (mean +/- SEM) and 297 +/- 80 pg/ml, respectively. Arm ischemia for 10 min induced by inflation of a cuff to 220 mm Hg led to a rise in TxB2 levels to 657 +/- 157 pg/ml after placebo (p less than 0.05) and 337 +/- 81 pg/ml after ketoconazole. One hour after cuff deflation, TxB2 returned to pre-ischemia levels in both groups. Platelet TxB2 concentrations were 27 +/- 6 ng in the placebo and 35 +/- 6 ng/10(9) platelets in the ketoconazole group, and were unchanged by cuff inflation. The fact that plasma and platelet TxB2 values were not lower 2 hr after ketoconazole treatment was explored in another group of four nonstressed volunteers who received 400 mg of drug. After 2 hr, TxB2 values had fallen from 170 +/- 30 pg to 120 +/- 10 pg; at 4 hr, 6 hr, and 8 hr they were 30 +/- 20 pg, 5 +/- 5 pg, and 5 +/- 5 pg/ml, respectively. These results indicate that tourniquet ischemia provokes TxA2 synthesis, and that the source of this prostanoid is likely to be ischemic tissue and not platelets. Finally, ketoconazole can profoundly inhibit both background and stimulated TxA2 synthesis.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Arm; Blood Platelets; Female; Humans; Ischemia; Ketoconazole; Male; Thromboxane A2; Thromboxane B2; Thromboxanes

Levels of immunoreactive 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha) and thromboxane B2 (TXB2) were measured in peripheral venous plasma in a group of volunteers and non-insulin dependent diabetic patients (NIDDS). Levels of these eicosanoids were close to the limit of sensitivity of the radioimmunoassays and consequently data are reported as maximal values. Basal plasma levels of 6-oxo-PGF1 alpha did not exceed 5 pg/ml in either group and maximal levels of immunoreactive TXB2 were 125 +/- 14 and 128 +/- 8 pg/ml for volunteers and NIDDS respectively. Attempts to elicit peripheral vascular prostacyclin biosynthesis in volunteers by using forearm ischaemia produced no increase in plasma 6-oxo-PGF1 alpha levels. Measurement of the combined plasma levels of 6-oxo-PGF1 alpha, 13,14-dihydro-6-oxo-PGF1 alpha, 13,14-dihydro-6,15-dioxo-PGF1 alpha and 6-oxo-PGE1 indicated that these were also low (less than 5 pg/ml) and that failure to demonstrate increased 6-oxo-PGF1 alpha levels was unlikely to have arisen from metabolism of prostacyclin to one or more of these metabolites. Measurement of 6-oxo-PGF1 alpha and TXB2 in peripheral venous plasma before and during chloropropamide alcohol flushing (CPAF) did not provide evidence for a role for these eicosanoids in the etiology of this phenomenon. These findings point to the need for a reappraisal of studies that have described altered plasma levels of 6-oxo-PGF1 alpha and TXB2 in CPAF and other pathophysiological conditions in man.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Chlorpropamide; Diabetes Mellitus, Type 2; Ethanol; Female; Flushing; Forearm; Humans; Indomethacin; Ischemia; Male; Middle Aged; Radioimmunoassay; Thromboxane B2; Thromboxanes

Thromboxane A2 (TxA2), an arachidonic acid metabolite causing vasoconstriction and platelet aggregation, is a putative mediator of coronary-artery vasospasm. To determine whether platelet-released TxA2 causes coronary arterial vasospasm, we measured plasma thromboxane B2 (TxB2, the inactive hydration product of TxA2) in the radial-artery and coronary-sinus blood of seven patients and performed therapeutic trials of antiplatelet agents in nine. Although coronary-sinus TxB2 levels rose from the base line approximately fivefold with spontaneous ischemia, samples drawn early in ischemia showed no rise over base-line values. Although a 150 mg dose of aspirin reduced urinary dinor-TxB2 levels by over 75 per cent, it had no effect on the course of the chronic recurrent form of angina pectoris due to vasospasm ("vasotonic angina"). Similarly, indomethacin had no effect on the frequency or duration of ischemia. TxA2 is unlikely to cause vasotonic angina, but it may be released during coronary vasospasm.

Topics: Adult; Angina Pectoris; Angina Pectoris, Variant; Arteries; Aspirin; Clinical Trials as Topic; Coronary Circulation; Coronary Vessels; Double-Blind Method; Female; Humans; Indomethacin; Ischemia; Male; Middle Aged; Recurrence; Thromboxane A2; Thromboxane B2; Thromboxanes; Time Factors; Veins

To determine whether treatment of horses with firocoxib affects recovery of ischemic-injured jejunum, while providing effective analgesia.. 18 horses.. Horses (n = 6 horses/group) received saline (0.9% NaCl) solution (1 mL/50 kg, IV), flunixin meglumine (1.1 mg/kg, IV, q 12 h), or firocoxib (0.09 mg/kg, IV, q 24 h) before 2 hours of jejunal ischemia. Horses were monitored via pain scores and received butorphanol for analgesia. After 18 hours, ischemic-injured and control mucosa were placed in Ussing chambers for measurement of transepithelial resistance and permeability to lipopolysaccharide. Histomorphometry was used to determine denuded villus surface area. Western blots for cyclooxygenase (COX)-1 and COX-2 were performed. Plasma thromboxane B(2) and prostaglandin E(2) metabolite (PGEM) concentrations were determined.. Pain scores did not significantly increase after surgery in horses receiving flunixin meglumine or firocoxib. Transepithelial resistance of ischemic-injured jejunum from horses treated with flunixin meglumine was significantly lower than in saline- or firocoxib-treated horses. Lipopolysaccharide permeability across ischemic-injured mucosa was significantly increased in horses treated with flunixin meglumine. Treatment did not affect epithelial restitution. Cyclooxygenase-1 was constitutively expressed and COX-2 was upregulated after 2 hours of ischemia. Thromboxane B(2) concentration decreased with flunixin meglumine treatment but increased with firocoxib or saline treatment. Flunixin meglumine and firocoxib prevented an increase in PGEM concentration after surgery.. Flunixin meglumine retarded mucosal recovery in ischemic-injured jejunum, whereas firocoxib did not. Flunixin meglumine and firocoxib were effective visceral analgesics. Firocoxib may be advantageous in horses recovering from ischemic intestinal injury.

Topics: 4-Butyrolactone; Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Blotting, Western; Clonixin; Cyclooxygenase 1; Cyclooxygenase 2; Eicosanoids; Electrophoresis, Polyacrylamide Gel; Horse Diseases; Horses; Ischemia; Jejunal Diseases; Sulfones; Thromboxane B2

To investigate the changes in plasma endothelin-1 (ET-1) , von Willebrand factor (vWF), serum 6-keto-prostaglandin(1alpha) (PGF(1alpha)) , thromboxane B2 (TXB2), platelet aggregation rate maximum (PAGm) and pancreatic blood flow after reproduction of severe acute pancreatitis (SAP) in rat, and the effect of recombinant staphylokinase (r-Sak) on SAP.. Eighty-one SD rats were divided randomly into the sham-operated group (n=27), the SAP model group (n=27), and the r-Sak treatment group (n=27). SAP was produced by administration of 5% sodium taurocholate into the pancreatic duct. The abdomen of rats was opened at 6, 12 and 18 hours after reproduction of SAP for determining the pancreatic blood flow. Blood was obtained at 6, 12 and 18 hours after reproduction of SAP for determining the concentration of plasma vWF with enzyme-labeled immunosorbent assay (ELISA). The concentration of plasma ET-1 and serum 6-keto-PGF(1alpha), and TXB2 were detected by radioimmunoassay. The PAGm induced by collagen and eicosanoids was assessed.. Pancreatic blood flow in the SAP group appeared to have a decreasing trend at 6,12 and 18 hours after operation and were significantly decreased at all time points after reproduction of the model, compared with those of the sham-operated group (all P<0.05). The PAGm, content of plasma ET-1, vWF, and TXB2 were significantly increased at all time points after reproduction of the model, while 6-keto-PGF(1alpha) was significantly decreased, compared with those of the sham-operated group (all P < 0.05). Compared with SAP model group, PAGm, the content of plasma ET-1, vWF, and serum TXB2 in the r-Sak group were decreased at all time points, however, the content of serum 6-keto-PGF(1alpha) was increased (all P<0.05).. The r-Sak can improve pancreatic microcirculation and enhance pancreatic blood flow in rats with SAP, and may be beneficial in the treatment of SAP.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Endothelin-1; Ischemia; Metalloendopeptidases; Pancreas; Pancreatitis; Platelet Aggregation; Random Allocation; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Thromboxane B2; von Willebrand Factor

We analyzed the involvement of thromboxane (TX) A2/prostaglandin (PG) H2 (TP) receptor in ischemia-induced neovascularization in mice.. Unilateral hindlimb ischemia was induced by right femoral artery ligature in male C57BL/6J mice (n=7 per group). Animals were then treated with or without TP receptor antagonist (S18886, 5 or 10 mg/kg per day; ramatroban, 10 mg/kg per day) or aspirin (30 mg/kg per day) in drinking water for 21 days. Hindlimb ischemia raised plasma level of TXB2, the stable metabolite of TXA2, by 4.7-fold. This increase was blocked by aspirin treatment whereas S18886 (5 or 10 mg/kg per day) had no effect. However, neither S 18886 nor aspirin affected postischemic neovascularization. We next assessed the putative involvement of TXA2 signaling in angiotensin II (Ang II) proangiogenic pathway. Ang II (0.3 mg/kg per day) enhanced TXB2 plasma levels by 2.6-fold over that of control (P<0.01). Ang II-induced TXB2 upregulation was reduced by cotreatment with Ang II type I receptor antagonist (candesartan, 20 mg/kg per day). Angiographic score, capillary number, and foot perfusion were improved by 1.7-, 1.7-, and 1.4-fold, respectively, in Ang II-treated mice compared with controls (P<0.05). Ang II proangiogenic effect was associated with a 1.6-fold increase in VEGF-A protein content (P<0.05) and a 1.4-fold increase in the number of Mac-3-positive cells (ie, macrophages) in ischemic areas (P<0.05). Interestingly, treatments with TP receptor antagonists or aspirin hampered the proangiogenic effects of Ang II.. Endogenous activation of TXA2 receptor by eicosanoids did not modulate spontaneous neovascularization in the setting of ischemia. Conversely, TXA2 signaling is involved in Ang II-induced AT1-dependent vessel growth.

Topics: Angiotensin II; Animals; Capillaries; Hindlimb; Ischemia; Male; Mice; Mice, Inbred C57BL; Naphthalenes; Neovascularization, Physiologic; Propionates; Receptors, Thromboxane A2, Prostaglandin H2; Signal Transduction; Thromboxane A2; Thromboxane B2; Vasculitis; Vasoconstrictor Agents

Ischemia, such as that caused by a tourniquet, stimulates thromboxane (Tx) A(2) synthesis. TxA(2) might sensitize the operated limb to various complications, such as compartment syndrome and thromboembolic events.. We studied the effect of pretreatment with a single dose of acetylsalicylic acid (ASA) (25, 100, and 500 mg) given 3 hours before surgery on the formation of TxB(2), a stable metabolite of TxA(2), after tourniquet deflation in 32 knee or ankle surgery patients.. Tourniquet time varied between 60 +/- 8 to 71 +/- 7 (SE) minutes. In control patients without ASA pretreatment, the platelet-produced femoral vein serum TxB(2) concentration over 30 minutes in vitro coagulation increased remarkably (from 40.0 +/- 20 ng/mL to 73.5 +/- 39 ng/mL) immediately after tourniquet deflation. Plasma concentrations increased similarly, approximately threefold. Pretreatment with 100 or 500 mg ASA prevented the increase in TxB(2) concentrations. Radial artery concentrations of TxB(2) were similar to venous concentrations in the different treatment groups.. Pretreatment with a single 100-mg dose of ASA prevents the release of TxB(2) after tourniquet deflation.

Topics: Adult; Aspirin; Humans; Ischemia; Thromboxane B2; Tourniquets

To investigate associations between structural, functional and circulatory placental changes in pregnancies complicated by impaired glucose metabolism.. Umbilical artery (UA) blood flow resistance was measured by Doppler velocimetry in 21 gravidae with diabetes/impaired glucose tolerance (IGT) and 10 healthy gravidae. Umbilical and placental vessel segments were incubated for determination of prostacyclin and thromboxane synthesis, and tissues histologically examined. Non-parametric statistical tests at a two-tailed P<0.05 were used.. Placental lesions were more common in diabetes/IGT and, although not being an uniform finding, in general associated with a higher vascular synthesis of thromboxane and/or lower prostacyclin/thromboxane synthesis ratio. As an exception, ischemic villitis was associated with a higher ratio and higher UA flow resistance.. Placental lesions are associated with an altered vascular prostanoid synthesis in diabetes/IGT, but not until structural signs of ischemia develop is a rise of UA blood flow resistance detected.

Topics: 6-Ketoprostaglandin F1 alpha; Diabetes Mellitus, Type 2; Diabetes, Gestational; Female; Glucose Intolerance; Humans; Infarction; Ischemia; Placenta; Placenta Diseases; Pregnancy; Pregnancy in Diabetics; Thrombosis; Thromboxane B2; Umbilical Arteries; Vascular Resistance

Prostacyclin (PGI2) is a short-lived endogenous inhibitor of platelet aggregation and a potent vasodilator and regulator of the growth of vascular smooth muscle cells. To study the role of PGI2 in the vascular system in vivo, PGI2-deficient (PGID) mice were established by genetic disruption of the PGI2 synthase gene.. PGI2 synthase-null mice were generated by replacing the exons of PGI2 synthase gene that encodes for the catalytic site of the enzyme with a neomycin resistance gene. In these mice, PGI2 levels in the plasma, kidneys, and lungs were reduced, whereas thromboxane and prostaglandin E2 levels became elevated. Blood pressure and the amounts of urea nitrogen and creatinine in plasma of the PGID mice were significantly higher than those of wild-type mice (P<0.05). They developed progressive morphological abnormalities in the kidneys, accompanied by atrophy, surface irregularity, fibrosis, cyst, arterial sclerosis, and hypertrophy of vessel walls. Thickening of the thoracic aortic media and adventitia were observed in aged PGID mice. Importantly, these phenotypes have not been reported in PGI2 receptor-deficient mice.. PGI2 deficiency resulted in the development of vascular disorders with the thickening of vascular walls and interstitial fibrosis, especially in mouse kidneys. The findings demonstrated in vivo that PGI2 is important in the homeostasis of blood vessels. Our established PGID mice are useful for studies on the initiation and development of vascular diseases, such as ischemic renal disorders with arterial sclerosis and infarction, and also for studies on the novel signaling pathway of PGI2.

Topics: Age Factors; Animals; Aorta, Thoracic; Blood Pressure; Blood Urea Nitrogen; Creatinine; Cytochrome P-450 Enzyme System; Dinoprostone; Disease Progression; Epoprostenol; Heart Rate; Infarction; Intramolecular Oxidoreductases; Ischemia; Kidney; Male; Mice; Mice, Knockout; Nephrosclerosis; Prostaglandins; Thromboxane B2

This study investigated the effects of a selective COX-2 inhibitor, FK3311, on warm ischemia-reperfusion (I/R) injury in the canine lung.. Sixteen adult mongrel dogs were used in this study. In the FK group (n = 8), FK (1 mg/kg) was administered intravenously 15 min before ischemia and 15 min before reperfusion. In the control group (n = 8), a vehicle was injected in the same manner. Warm ischemia was induced for 3 h by clamping the left pulmonary artery, veins, and bronchus. Five-minute clamping tests of the right pulmonary artery were performed before ischemia and 30 min after reperfusion. During the test, left pulmonary vascular resistance (L-PVR), cardiac output (CO), and arterial oxygen pressure (PaO(2)) were measured. The lung specimens were simultaneously harvested for wet-to-dry weight ratio (WDR) measurements, histopathological studies, and polymorphonuclear neutrophil (PMN) counts. Serum thromboxane (Tx) B(2) and 6-keto-prostaglandin (PG) F(1alpha) (stable metabolites of TxA(2) and PGI(2), respectively) were also measured 30 min after reperfusion.. L-PVR, CO, PaO(2), and WDR were significantly (P < 0.05) better in the FK group than in the control group. Histological tissue edema was mild, and PMN infiltration was significantly (P < 0.05) reduced in the FK group compared to the control group. The serum TxB(2) levels were significantly (P < 0.05) lower in the FK group than in the control group, while 6-keto-PGF(1alpha) levels were not significantly (P < 0.05) reduced. Two-day survival rate was significantly (P < 0.05) better in the FK group than in the control group.. FK has protective effects on pulmonary I/R injury stemming from marked inhibition of TxA(2).

Topics: 6-Ketoprostaglandin F1 alpha; Anilides; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cardiac Output; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dogs; Epoprostenol; Hemodynamics; Ischemia; Isoenzymes; Lung; Neutrophils; Oxygen; Partial Pressure; Prostaglandin-Endoperoxide Synthases; Pulmonary Artery; Pulmonary Circulation; Pulmonary Veins; Reperfusion Injury; Thromboxane B2; Time Factors; Vascular Resistance

Membrane phospholipid breakdown, caused by ischemia and reperfusion (I/R) of the liver, releases free fatty acids including arachidonic acids and lysophospholipids, which serve as precursors of various inflammatory lipid derivatives. Phospholipase A2 (PLA2) is a key enzyme that initiates this reaction. In this study, we tested our hypothesis that a type II PLA2 inhibitor, LY329722, could attenuate hepatic I/R injury caused by a 2-hr total hepatic vascular exclusion (THVE) in dogs.. Eighteen beagle dogs, subjected to a 2-hr THVE, were divided into three groups. Group 1 (n=6) was untreated and served as a control group. LY329722 was administered to animals in group 2 (n=6) intravenously (0.2 mg x kg(-1) x hr(-1)) for 60 min before ischemia, and to animals in group 3 (n=6) for 60 min starting 15 min before reperfusion (0.2 mg x kg(-1) x hr(-1)). Animal survival, systemic and splanchnic hemodynamics, hepatic tissue blood flow, liver functions, energy metabolism, hepatic venous thromboxane B2 and endothelin-1 levels, phospholipid levels and tumor necrosis factor-a mRNA expression in liver tissue, and histopathologic findings were evaluated.. Two-week animal survival was 33% (two of six) in group 1, and 100% (six of six) in groups 2 and 3. LY329722 improved systemic and splanchnic hemodynamics, hepatic tissue blood flow, and energy metabolism, reduced liver enzyme, thromboxane B2, and endothelin-1 release, prevented hepatic phospholipid degradation and tumor necrosis factor-alpha mRNA expression, and lessened histopathologic damage and the number of neutrophil infiltrating into the liver tissue.. The present study demonstrated that a type II PLA2 inhibitor, LY329722, attenuated hepatic I/R injury caused by a 2-hr THVE model in dogs.

Topics: Acetates; Animals; Dinoprost; Dogs; Endothelin-1; Energy Metabolism; Enzyme Inhibitors; Female; Hemodynamics; Indoles; Ischemia; Liver; Liver Circulation; Liver Function Tests; Phospholipases A; Phospholipases A2; Regional Blood Flow; Reperfusion Injury; Splanchnic Circulation; Thromboxane B2; Time Factors; Transcription, Genetic; Tumor Necrosis Factor-alpha

Topics: Anilides; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cardiac Output; Dogs; Hemodynamics; Ischemia; Lung; Models, Animal; Oxygen; Partial Pressure; Pulmonary Artery; Pulmonary Circulation; Pulmonary Veins; Reference Values; Reperfusion Injury; Thromboxane B2; Vascular Resistance

Intestinal reperfusion (IR)-induced pulmonary edema has been related to endogenous pulmonary thromboxane A2 (TxA2) release. This study examines the hypothesis that alveolar macrophages (aMphis) activated during IR are an important cellular source of TxA2 in this model. Anesthetized Sprague Dawley rats underwent 120 min of intestinal ischemia and 60 min of reperfusion (IR) or sham operation (Sham). aMphis were isolated by bronchoalveolar lavage and incubated in Krebs buffer for 30 min, after which the supernatant was analyzed for TxB2 (metabolite of TxA2) and prostaglandin E2. Other parameters of aMphi activation measured included lysosomal enzyme release (beta-glucuronidase), superoxide (O2-) release, and procoagulant activity. aMphis from animals sustaining IR generated more than twice as much TxA2 and prostaglandin E2 as did those isolated from controls (p < .05). Other evidence of aMphi activation included a nearly 100-fold increase in procoagulant activity, a 7-fold increase in beta-glucuronidase release, and a 2.5-fold increase in O2- release over that of controls (p < .05). These data suggest that TxA2 is a major eicosanoid product of aMphis during IR and that aMphis may be an important cellular participant in IR-induced pulmonary microvascular injury, either directly by releasing O2-, lysosomal enzymes, and pro-coagulant factors, or indirectly by generating TxA2.

Topics: Animals; Blood Coagulation; Cells, Cultured; Dinoprostone; Glucuronidase; Intestines; Ischemia; Lysosomes; Macrophage Activation; Macrophages, Alveolar; Male; Mesenteric Arteries; Pulmonary Edema; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxides; Thromboxane B2

To test the hypothesis that ischemia and reperfusion injury may contribute to the cause or nonhealing of venous ulcers, the effects of postural change on the microcirculation of ulcers and on levels of known mediators of reperfusion injury in their venous effluent were studied.. A standard protocol of stabilization (20 minutes), limb dependency (1 hour), and reelevation (2 hours) was used in 10 patients with venous leg ulcers as proven by clinical history, examination, ankle-brachial pressure index, and light reflective rheography. Superficial blood flow in and around ulcers was repeatedly examined with a new laser-Doppler scanning technique. Blood samples from the saphenous vein or a tributary adjacent to the ulcer before dependency and at 0, 10, 30, 60, and 120 minutes after reelevation were analyzed for tumor necrosis factor-alpha, interleukin (IL)-1RA, IL-1 beta, IL-6, platelet-activating factor, thromboxane B2, leukotriene B4, and P-selectin.. Scans showed a consistent pattern of high ulcer blood flow, which decreased on dependency (p < 0.05) and then returned to baseline levels on reelevation and (in 7 of 10) eventually exceeded initial values. Mediator assays showed that levels of platelet-activating factor, IL-1RA, and IL-6 were significantly higher in resting ulcer venous effluent than in systemic venous samples; the reverse was true for P-selectin. There was no statistically significant change in effluent concentration of any mediator as a function of posture, ulcer size, or healing.. Postural vasoregulation causes relative ischemia and reperfusion in venous leg ulcers. However, this is not associated with changes in release of mediators known to be related to reperfusion injury in internal organs.

Topics: Aged; Aged, 80 and over; Blood Pressure; Cytokines; Humans; Interleukin-1; Interleukin-6; Ischemia; Laser-Doppler Flowmetry; Leg; Leukotriene B4; Microcirculation; Middle Aged; P-Selectin; Platelet Activating Factor; Plethysmography, Impedance; Posture; Receptors, Interleukin-1; Regional Blood Flow; Reperfusion Injury; Thromboxane B2; Treatment Outcome; Tumor Necrosis Factor-alpha; Varicose Ulcer; Vasomotor System; Wound Healing

Topics: Adult; Extracellular Space; Humans; Ischemia; Male; Microdialysis; Muscle, Skeletal; Reference Values; Reperfusion; Thromboxane B2

ANP model in rats was used to determine the concentration of TXB2, PGF1 alpha in plasma and the ACE activity in serum in five groups. The concentration of TXB2, PGF1 alpha in all experimental groups was significantly different from that of control group (P < 0.05). The comparison of ACE activity was just the same as the above except that of 6 h. The factors leading to pancreatic ischemia functioned continously. We conclude that pancreatic ischemia is a continuous injury factor in ANP, and there is no reperfusion-injury in the course of the disease.

Topics: Animals; Female; Ischemia; Male; Pancreas; Pancreatitis, Acute Necrotizing; Peptidyl-Dipeptidase A; Prostaglandins F; Rats; Rats, Sprague-Dawley; Taurocholic Acid; Thromboxane B2

The pathophysiology of ischemia-reperfusion renal injury is mediated, in part, by the generation of the vasoconstricting prostanoid thromboxane A2 (TXA2). This study was undertaken to evaluate the renoprotective effects, as well as the optimal timing and dosage, of a selective thromboxane synthetase inhibitor, OKY-046, in a unilateral nephrectomized, 60 min ischemia, 72 hr reperfusion, rodent model. Forty-one rats were subjected to right nephrectomy only (group A), or right nephrectomy with 60 min of left renal ischemia and treatment with inactive vehicle only (group B), or 2 mg/kg or 4 mg/kg of OKY-046 administered intravenously before (groups C and D) or after (groups E and F) pedicle clamping. Outcome variables included animal survival; change in kidney weight; 0, 24, and 72 hr plasma creatinine (CR); urea nitrogen (BUN); thromboxane B2 (TXB2) and 6-keto prostaglandin F(1alpha) (6 kPGF(2alpha)) levels; creatinine clearance (CRCL); and histologic evidence of renal injury. Animal survival and postperfusion kidney weight were not significantly different among the groups. However, renal functional parameters were significantly improved with the 2 mg/kg dose of OKY-046 administered after renal ischemia. (group B 72 hr Cr= 8.01 +/- 1.1 mg% vs. group E=3.99 +/- 1.5 mg%, and group B 72 hr BUN=241.3 +/- 32.8 mg% vs. group E=52.6 +/- 22.5 mg%). The CRCL was also improved in group E vs. group B, although these results did not reach statistical significance (group B=0.069 ml/min vs. group E=0.194 ml/ min). The 24 hr TXB2 levels were significantly increased in group B (0 hr=754.1 +/- 219.4 pg/ml vs. 24 hr=2055.9 +/- 550.0 pg/ml), and pre- or posttreatment with OKY-046 abrogated this increase (group C 0 hr=517.1 +/- 80.9 pg/ml vs. 24 hr=384.7 +/- 251.5 pg/ml, and group E 0 hr=781.6 +/- 390.4 pg/ml vs. 24 hr=183.0 +/- 81.4 pg/ml). The 24 hr 6 kPGF(1alpha) levels decreased in all groups, whereas 72 hr 6 kPGF(1alpha) levels increased above baseline in groups A, C, and E, but not in group B. These data demonstrate the beneficial effects of thromboxane A2 synthesis inhibition in the setting of ischemia-reperfusion injury and suggest that this renoprotection correlates with late vasodilatory prostanoid synthesis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Enzyme Inhibitors; Hot Temperature; Ischemia; Kidney; Male; Methacrylates; Organ Preservation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thromboxane B2; Thromboxane-A Synthase

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Carotid Arteries; Dinoprostone; Female; Hepatic Veins; Hypertonic Solutions; Ischemia; Liver Transplantation; Male; Organ Preservation; Swine; Temperature; Thromboxane B2

To determine the role of thromboxane A2 (TxA2) in ischemic damage of the rat liver, we examined the effects of a TxA2 synthetase inhibitor (OKY 046) and a TxA2 receptor antagonist (ONO 3708). Rats were divided into three groups. In group I, a portion of the liver was subjected to 100 min of warm ischemia and the remaining liver resected. In group II, OKY 046 (30 mg/kg, intravenously) was given 5 min before the same procedure. In group III, ONO 3708 (10 mg/kg, intravenous) was given 5 min before ischemia. We then assessed survival, serum biochemistry, extent of histologic necrosis, and the levels of prostaglandin E2 (PGE2), TxB2, and 6-keto-PGF1-alpha. Pretreatment with OKY 046 and ONO 3708 significantly improved survival, decreased the tissue water content, and lowered the levels of serum transaminases and the extent of histological liver necrosis compared with the control group. OKY 046 markedly suppressed the level of TxB2, but not the levels of PGE2 or 6-keto-PGF1-alpha. ONO 3708 did not change the levels of PGE2, TxB2, or 6-keto-PGE1-alpha. In a liver perfusion model, OKY 046 and ONO 3708 did not suppress the uptake of trypan blue in hepatocytes. Our results demonstrate that either a TxA2 synthetase inhibitor or a TxA2 receptor antagonist can protect the liver from an ischemic insult. The effects of these drugs were due to inhibition of TxA2 synthesis and TxA2 blockade at the receptor, without modulating PGI2 or PGE1. Our results in a perfused rat liver model suggest that these drugs work during reperfusion and prevent postischemic tissue edema.

Topics: Animals; Blood Glucose; Hot Temperature; Ischemia; Liver; Liver Circulation; Male; Methacrylates; Rats; Rats, Sprague-Dawley; Reperfusion; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Transaminases

Eicosanoids play an important role in mediating deleterious effects following skeletal muscle ischemia-reperfusion injury. It has previously been shown that oxygenated perfluorocarbon emulsion (O2 Fluosol-DA 20%) decreases the amount of muscle necrosis and neutrophil sequestration when given during the reperfusion phase following skeletal muscle ischemia. As thromboxane is known to alter the endothelial cytoskeleton, thereby favoring diapedesis of neutrophils, the effects of O2 Fluosol-DA 20% on thromboxane release in a canine gracilis muscle model were investigated. The gracilis muscle on one randomly selected side of 14 adult mongrel dogs (body-weight 22-26 kg) was subjected to 6 h of normothermic ischemia followed by 48 h of normothermic reperfusion. The control group (n = 7) underwent ischemia-reperfusion, but without any pharmacological intervention. The Fluosol group (n = 7) were infused with O2 Fluosol-DA 20% (4.3(0.2) ml O2/100 ml) at 12 ml/min for 40 min via the gracilis artery following the ischemic period. Thromboxane B2 levels were measured from blood samples obtained at pre-ischemia, and at 1 h and 48 h of reperfusion. The gracilis muscles were harvested at the end of the experiment and extent of muscle necrosis quantitated by serial transections, nitroblue tetrazolium staining and computed planimetry. The mean(s.e.m.) muscle necrosis in the control group (59(6)%) was significantly higher than in the Fluosol group (22(5)%, P < 0.05, t-test). Thromboxane levels (pg/ml) in the control group at 1 h of reperfusion were significantly higher than the pre-ischemic and 48-h reperfusion levels (7286(1383) versus 1336(592) and 2314(1297), P < 0.05 by ANOVA and Student-Newman-Keuls test). The thromboxane level in the Fluosol group at 1 h reperfusion was significantly lower than the control group (2700(556) and 7286(1383) pg/ml, respectively; P < 0.05, t-test). In contrast, there was no statistically significant difference between thromboxane levels in the Fluosol group at 1 h reperfusion compared with levels at pre-ischemia and 48 h reperfusion (2700(556) versus 1336(592) and 1400(474). Thus, perfluorocarbons are effective in decreasing skeletal muscle necrosis, probably by maintaining the endothelial integrity and preventing vasospasm, secondary to their inhibitory effect on thromboxane release. Perfluorocarbons may also minimize some of the deleterious pulmonary effects known to be caused by increased levels of eicosanoids during reperfusion.

Topics: Animals; Blood Substitutes; Dogs; Drug Combinations; Eicosanoids; Fluorocarbons; Hydroxyethyl Starch Derivatives; Ischemia; Muscle, Skeletal; Necrosis; Neutrophils; Oxygen Consumption; Reperfusion Injury; Thromboxane B2

Prostacyclin (PGI2) and thromboxane A2 (TXA2) play an important role in the pathophysiology of various cardiovascular diseases. The balance between PGI2 and TXA2 regulates the interaction between platelets and the vessel wall in vivo. In this study we measured PGI2 and TXA2 synthesis by analysing their urinary index metabolites 2,3-dinor-6-keto-PGF1 alpha and 11-dehydro-TXB2, respectively, in acute (10 patients) and chronic (10 patients) lower limb ischaemia. Both PGI2 and TXA2 synthesis were increased about two-fold in patients with acute lower limb ischaemia compared to chronic lower limb ischaemia. However, the PGI2/TXA2 ratio was more or less the same in acute and chronic lower limb ischaemia. In patients with acute lower limb ischaemia caused by thrombotic occlusion, PGI2 and TXA2 formation were about two times higher than in patients with acute lower limb ischaemia caused by embolic occlusion. Elevation of PGI2 and TXA2 synthesis in acute lower limb ischaemia may reflect increased platelet-vascular wall interactions without changing the PGI2/TXA2 ratio.

Topics: 6-Ketoprostaglandin F1 alpha; Aged; Aged, 80 and over; Chronic Disease; Creatinine; Epoprostenol; Extremities; Female; Humans; Ischemia; Male; Middle Aged; Thrombosis; Thromboxane A2; Thromboxane B2

Topics: Analysis of Variance; Animals; Antioxidants; Dogs; Edema; In Vitro Techniques; Ischemia; Muscle, Skeletal; Necrosis; Peroxidase; Pregnatrienes; Reperfusion; Reperfusion Injury; Steroids, Heterocyclic; Thromboxane B2; Time Factors

The tissue kinetics of key metabolites of ischaemic and postischaemic tissue damage were studied in the intercellular space of human skeletal muscle by microdialysis. In vivo microdialysis calibration experiments (n = 5) yielded the basal intercellular concentration of glucose in human skeletal muscle (3.6 +/- 0.6 mM; mean +/- SD). The corresponding mean plasma glucose concentration was 4.3 +/- 0.2 mM which was significantly higher. The time vs. concentration profiles of intercellular glucose (n = 7), lactate (n = 5), TxB2 (n = 6) and urea (n = 8) were characterized during a 20 min period of leg constriction. TxB2 increased exclusively during reperfusion in comparison to baseline (n = 6). Administration of 500 mg acetylsalicylic acid, 5-10 min after onset of ischaemia blunted TxB2-response to reperfusion (n = 4). It is concluded that intercellular muscle glucose concentration is less than that in plasma. Glucose uptake in skeletal muscle is rapid even under ischaemic conditions. Synthesis and release of TxB2 is not evident during ischaemia. TxB2 mediated reperfusion injury might be reduced by acetylsalicylic acid, even if administered after onset of ischaemia.

Topics: Adult; Glucose; Humans; Ischemia; Lactates; Lactic Acid; Male; Microdialysis; Muscle, Skeletal; Reperfusion; Thromboxane B2

Defibrotide is a polydeoxyribonucleotide-derived anti-ischemic drug with multiple sites of action involving both plasmatic and cellular targets. This agent has been demonstrated to produce profibrinolytic, cytoprotective, and vaso-facilatory actions. Since monocytes are increased in the mediation of some of the pathophysiologic responses seen in ischemic disorders, the functional properties of these cells were investigated in experimental conditions to evaluate their behavior during resting and stimulated states. Defibrotide was supplemented in these systems to determine its modulatory action. In this investigation Defibrotide was found to decrease the PAI-1 levels and may indicate that this may be the mechanism for its profibrinolytic actions. Defibrotide was also found to reduce the procoagulant activity of monocytes in these experimental settings. Both PAI and procoagulant factors play an important role in the pathophysiology of inflammation, DIC, and ischemia. Defibrotide induced reduction of these two factors represents the mechanism whereby this agent produces its therapeutic action.

Topics: Blood Coagulation Factors; Cytokines; Fibrinolytic Agents; Hemostasis; Humans; Ischemia; Monocytes; Plasminogen Activator Inhibitor 2; Polydeoxyribonucleotides; Thromboxane B2

This study examines the hypothesis that pentoxifylline protects renal PGE2 synthesis during mesenteric ischemia/reperfusion injury. Anesthetized Sprague-Dawley rats (300 g) were subjected to sham or superior mesenteric artery occlusion for 20 min followed by 30 min of reperfusion. The ischemia/reperfusion groups received either enteral allopurinol (10 mg/kg) daily for 5 d prior to ischemia, pentoxifylline (50 mg/kg) 10 min prior to ischemia or carrier. The kidney was removed and perfused in vitro with oxygenated Krebs buffer and the effluent was assayed for release of 6-keto-PGF1 alpha, PGE2 and thromboxane B2 (TXB2) by enzyme immunoassay. Mesenteric ischemia/reperfusion decreased renal PGE2 release by 50% (compared to sham) but did not alter release of TXB2 or 6-keto-PGF1 alpha. Pentoxifylline pretreatment (not allopurinol) preserved renal PGE2 release at the sham level. These data showed pentoxifylline exerted a protective effect against severe mesenteric ischemia/reperfusion injury by maintaining release of renal PGE2, a potent endogenous renal vasodilator.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Pressure; Constriction; Dinoprostone; Heart Rate; In Vitro Techniques; Ischemia; Kidney; Male; Mesenteric Arteries; Pentoxifylline; Rats; Rats, Sprague-Dawley; Reperfusion; Thromboxane B2

The standard preservation technique in lung transplantation is cold single pulmonary artery flush (PAF) with Eurocollins solution (ECS). We compared ECS with University of Wisconsin (UW) solution, with and without added indomethacin, in single PAF preservation in an in vivo rabbit model of warm ischemia-reperfusion lung injury. Six groups of four New Zealand white rabbits each underwent isolation and hilar stripping of the left lung. In the four experimental groups, the left lung was flushed with (15 ml/kg) of cold ECS or UW solution, with or without added indomethacin, before warm ischemia for 120 minutes and before reperfusion for 60 minutes. The remaining two groups were the nonischemic and the ischemic "no flush" controls. Transcapillary flux of 99mTechnitium-labeled albumin and electron microscopy were used to demonstrate lung injury. Pulmonary vascular resistance (PVR) and thromboxane B2 (TXB2) concentrations were measured. There was a significant rise in PVR after ischemia/reperfusion in the ischemic control group (54.7 +/- 13.9 to 117.8 +/- 20.7 mm Hg/L.min-1, P < 0.05). The net rise in PVR after ischemia-reperfusion was significantly smaller in the two groups in which indomethacin was added (16.8 +/- 17.5 and 4.5 +/- 10.6 mm Hg/L.min-1 for UW and ECS, respectively) compared with the ischemic control (63.1 +/- 24.6 mm Hg/L.min-1, P < 0.05). Post-reperfusion TXB2 levels tended to be lower in the nonischemic control group and in the indomethacin-flush groups. We conclude that the increase in PVR produced by unilateral ischemia-reperfusion lung injury in this model was improved by single PAF perfusion. There was no significant difference between UW solution and ECS in this regard. The addition of indomethacin to the flush solution was associated with lower PVRs as well as morphologic improvement by electron microscopy. These findings may indicate a prominent role for the provision of PG synthesis inhibition during preservation for lung transplantation.

Topics: Adenosine; Allopurinol; Animals; Blood Pressure; Glutathione; Hypertonic Solutions; Indomethacin; Insulin; Ischemia; Lung; Organ Preservation; Organ Preservation Solutions; Oxygen; Partial Pressure; Pulmonary Artery; Rabbits; Raffinose; Reperfusion; Thromboxane B2; Vascular Resistance

Contralateral uninephrectomy attenuates unilateral renal ischemic injury. The present work was performed to elucidate whether the beneficial effect of uninephrectomy was mediated through the modification of the actions of thromboxane A2 (TxA2) or prostacyclin. Unilateral ischemic injury was provoked by a 60-minute left renal artery occlusion in right nephrectomized (Nx) and in sham-nephrectomized (Sham-Nx) rats. Inulin clearance (CIn) of left kidney 48 hours after ischemia was significantly higher in the Nx group than in the Sham-Nx group (0.11 +/- 0.07 vs. 0.00 +/- 0.00 ml/min/kidney, P < 0.05). Ischemia-induced tubular necrosis was also less in Nx animals. Proliferating cell nuclear antigen (PCNA) staining, a marker for cell proliferation, was found more markedly in Nx rats than in Sham-Nx animals. Forty-eight hours after ischemia, renal cortical TxB2 content was greater in Sham-Nx rats than in Nx rats (29.5 +/- 4.4 vs. 18.3 +/- 1.7 pg/mg protein, P < 0.05). No significant difference was found in the intrarenal content of 6-keto prostaglandin F1 alpha between two ischemia groups. A thromboxane synthetase inhibitor, OKY-046 (100 mg/kg/day, i.p.), significantly increased CIn 48 hours after ischemia (0.00 +/- 0.00 vs. 0.17 +/- 0.09 ml/min/kidney, P < 0.05) and attenuated ischemic tubular damage in Sham-Nx rats but not in Nx animals. Under OKY-046 treatment, no significant difference was found in postischemic CIn and ischemic tubular damage between the Nx and Sham-Nx groups. OKY-046 also increased PCNA expression in the cortex and outer stripe in Sham-Nx animals. These data suggest that less production of intrarenal TxB2 plays an important role for the uninephrectomy-induced attenuation of ischemic renal damage and for the facilitation of tubular recovery.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Epoprostenol; Ischemia; Kidney; Male; Methacrylates; Nephrectomy; Proliferating Cell Nuclear Antigen; Rats; Rats, Sprague-Dawley; Renal Circulation; Staining and Labeling; Thromboxane A2; Thromboxane B2

Ischemia-reperfusion injury has been studied in various organs. Effects of leukocyte and platelet depletion on ischemia-reperfusion injury were evaluated using the isolated, perfused dog pancreas in vivo.. Pancreatic exocrine and endocrine functions were stimulated by an intra-arterial injection of cholecystokinin (10(-12) mol) and intravenous injection of glucose and arginine (1 g/kg body wt), respectively. The functions before and after 60 minutes of ischemia were evaluated in the no treatment and in the leukocyte and platelet depletion groups.. Cholecystokinin increased prostaglandin I2 and thromboxane A2 production and stimulated exocrine pancreatic secretion. Glucose and arginine stimulated insulin and glucagon release from the pancreas. Sixty minutes of ischemia followed by 60 minutes of reperfusion damaged the pancreatic acinar and ductular cells. Ischemia of 60 minutes followed by 90 minutes of reperfusion damaged beta cells. Removal of leukocytes (97.6%) and platelets (99.4%) by using a filter throughout the experiment prevented the ischemia-reperfusion injury, reduced plasma lipid peroxide and thromboxane A2, and increased prostaglandin I2 levels.. Leukocytes and platelets seem to damage the pancreas during ischemia-reperfusion by increasing the peroxidation of structurally important cell membrane lipids and reduced the thromboxane A2 prostaglandin I2 ratio, a predictor of cellular injury.

Topics: 6-Ketoprostaglandin F1 alpha; Amylases; Animals; Blood Platelets; Dogs; Female; In Vitro Techniques; Ischemia; Leukocyte Count; Leukocytes; Lipid Peroxides; Male; Pancreas; Pancreatic Hormones; Platelet Count; Reperfusion Injury; Thromboxane B2; Veins

Urinary 2,3-dinor-thromboxane B2 (2,3-dinor-TXB2), an enzymatic degradation product of TXB2, is currently measured for evaluating in vivo thromboxane biosynthesis in rats. We simultaneously measured 2,3-dinor-TXB2 and 2,3-dinor-TXB1, another product of TXB2 metabolism, in the urine of rats by immunoaffinity extraction/gas chromatography negative ion chemical ionization mass spectrometry (GC-NICIMS). In rats under basal conditions, urinary excretion of 2,3-dinor-TXB1 was much higher than that of 2,3-dinor-TXB2 (19.22 +/- 4.86 and 1.64 +/- 0.29 ng/24 h, respectively). The relative abundance of the two metabolites in each animal was fairly constant (91.9 +/- 1.6 and 8.1 +/- 1.6% of their sum, respectively). Urinary excretion of both 2,3-dinor-TXB1 and 2,3-dinor-TXB2 increased in rats undergoing in vivo hepatic ischemia-reperfusion. Other thromboxane metabolites, including 11-dehydro-TXB2 and 11-dehydro-2,3-dinor-TXB2, were measured by GC-NICIMS in selected urines. The resulting profile was: 2,3,4,5-tetranor-TXB1 > 2,3-dinor-TXB1 >> 11-dehydro-TXB2 > 2,3-dinor-TXB2 = TXB2. This study shows that urinary 2,3-dinor-TXB1 is a suitable parameter of TXB2 biosynthesis in vivo in rats. The possible cross-reactivity of 2,3-dinor-TXB1 in immunoassays of urinary 2,3-dinor-TXB2 or even TXB2 in rats should be considered in future studies.

Topics: Animals; Ischemia; Liver; Male; Mass Spectrometry; Rats; Rats, Sprague-Dawley; Reperfusion; Thromboxane B2; Thromboxanes

We examined the hepatoprotective effect of a prostaglandin (PG)I2 analogue by analyzing the endogenous release of prostanoid from the pig liver. Fourteen female pigs underwent 1 hr complete hepatic vascular exclusion (HVE); the portal and vena caval circulation was actively decompressed. The animals were divided into one of two groups (n = 7, each) according to pretreatment with the prostacyclin analogue (OP 2507, OP) administered via a mesenteric vein branch for 30 min at a rate of 2 micrograms/kg/min immediately prior to HVE. The plasma levels of prostaglandin E2 (PGE2), 6-keto-prostaglandin F1-alpha (6-keto-PGF1 alpha), and thromboxane B2 (TXB2), from the blood samples from the aorta, the hepatic vein, and the portal vein were serially compared for 60 min after the restoration of blood flow. Other parameters included 7-day survival rate, serum biochemistry, and endotoxin assay. A significant improvement in 7-day survival rate (6/7 vs. 1/7 for the control, P < 0.02) was observed in the OP-treated animals, associated with amelioration of serum transaminase activities but with no differences in plasma endotoxin levels. The reperfused liver progressively and substantially released PGE2 but did not generate other prostanoids (TXB2 and 6-keto-PGF1 alpha). OP pretherapy substantially suppressed hepatic generation of the PGE2 postreflow, correlating with serum transaminase levels (rs = 0.80; P < 0.01, at 60 min). We conclude that the PGI2 analogue ameliorates hepatic ischemia/reperfusion injury by down-regulating PGE2 production from the reperfused liver.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspartate Aminotransferases; Cryoprotective Agents; Dinoprostone; Endotoxins; Epoprostenol; Female; Ischemia; Liver; Prostaglandins; Swine; Thromboxane B2

To clarify the role of thromboxane A2 synthetase inhibitor (CV-4151) in the ischemia-reperfusion injury, the effect of CV-4151 was investigated in the gastrocnemius muscles of female Lewis rats. All tissues except femoral vessels were transected at the midthigh level and 4 h of ischemia was induced by vascular clamping of the femoral artery and vein, followed by 1 h of reperfusion. The sham group (n = 8) underwent the operation without ischemia-reperfusion; the control group (n = 8) with ischemia-reperfusion, and the CV-4151 group (n = 8) was pretreated with CV-4151 20 mg/kg. Skeletal muscle blood flow was measured by a hydrogen gas clearance method; the blood flow restored fully in the CV-4151 group, while it remained significantly low in the control group after 1 h of reperfusion (p < 0.05). Tissue levels of adenosine triphosphate (ATP) and creatine phosphate (PCR) were measured after 1 h of reperfusion; ATP decreased to 25% of nonischemic values in the control group. In contrast, premedication with CV-4151 significantly improved the recovery of ATP (p < 0.01). PCR showed the same tendency as ATP; CV-4151 also improved the recovery of PCR significantly (p < 0.05), but CV-4151 did not prevent the production of lipid peroxides. Serum thromboxane B2 was determined by radioimmunoassay; in the sham and the CV-4151 group the level was significantly lower than in the control group (p < 0.05). was significantly lower than in the control group (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenine Nucleotides; Adenosine Triphosphate; Animals; Fatty Acids, Monounsaturated; Female; Ischemia; Lipid Peroxides; Muscles; Phosphocreatine; Pyridines; Rats; Rats, Inbred Lew; Regional Blood Flow; Reperfusion; Thromboxane B2; Thromboxane-A Synthase

Six patients undergoing vascular reconstructive surgery were examined for evidence of oxygen-derived free radical (ORF) damage to the protein, immunoglobulin G (IgG). OFR damage was determined as an increase in the fluorescence (ex 360 nm em 454 nm) to ultraviolet absorption (280 nm) ratio of IgG, representing N-Formyl kynurenine and other as yet unidentified fluorophores. The IgG ratio was found to increase slightly during ischaemia and to undergo marked elevation upon reperfusion (275 +/- 405% baseline value at 40 min post-clamp; mean +/- sd). A high ratio was maintained post-reperfusion, even after 60 min reperfusion. Determination of thromboxane B2, (TXB2), leukotriene B4, (LTB4) and 6-keto prostaglandin F1 alpha, (PGF1a), revealed a decrease in their concentrations during ischaemia and a transient, marked increase on reperfusion. Only TXB2 concentrations were found to correlate with the IgG ratio (negative correlation, p < 0.05). No correlation was observed between von Willebrand antigen factor, a marker of endothelial cell damage and fluorescent IgG ratio. However, levels of the factor increased slightly during ischaemia and more sharply upon reperfusion. These preliminary results therefore suggest that a more likely source of the OFRs responsible for IgG damage is endothelial cell xanthine oxidase, rather than cyclo-oxygenase or lipoxygenase.

Topics: Aged; Free Radicals; Humans; Immunoglobulin G; Ischemia; Leg; Leukotriene B4; Middle Aged; Prostaglandins F; Reperfusion Injury; Thromboxane B2; Vascular Surgical Procedures; von Willebrand Factor

The implication of eicosanoid metabolism and its relationship with oxygen free radical production in the process of ischemia-reperfusion associated with rat pancreas transplantation has been explored in this study. For this purpose male Sprague-Dawley rats were classified as follows: group I, control animals not surgically manipulated; group II, pancreas transplantation, after 30 min preservation in UW solution; group III, pancreas transplantation after 12 h preservation under the same conditions; group IV, same as group III but with administration of SOD 5 min prior to organ revascularization. The results show post-transplantation increases in 6-keto-PGF1 alpha, TXB2, LTB4 and 12-HETE in pancreatic tissue independent of preservation time. The fact that SOD administration could reverse these increases even though an efficient xanthine oxidase irreversible inhibitor such as allopurinol was present in the preservation solution suggests that eicosanoid generation in the recipient rat would be mediated by an oxygen free radical dependent mechanism not exclusively dependent on endothelial xanthine oxidase activity.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Cold Temperature; Free Radicals; Hydroxyeicosatetraenoic Acids; Ischemia; Leukotriene B4; Male; Organ Preservation; Pancreas; Pancreas Transplantation; Rats; Rats, Sprague-Dawley; Reperfusion; Superoxide Dismutase; Thromboxane B2

Thromboxane A2, leukotriene B4, and NE are all released from ischemic muscle during reperfusion. Thromboxane A2 levels peaked at 10 min and this potent vasoconstrictor may be responsible for low reflow. Neutrophil elastase levels did not rise until 240 min of reperfusion, following that of leukotriene B4 at 120 min, indicating that neutrophil recruitment and activation is a relatively late event following revascularization. In conclusion, it would appear that endothelial factors have a significant role in the vasomotor changes that account for low reflow. Equally altered neutrophil function almost certainly contributes to the final development of reperfusion injury.

Topics: Animals; Endothelium, Vascular; Ischemia; Leukocyte Elastase; Leukotriene B4; Muscles; Neutrophils; Pancreatic Elastase; Rats; Regional Blood Flow; Reperfusion Injury; Thromboxane B2

To evaluate the role of thromboxane A2 (TXA2) in ischemic liver injury, the serum changes in thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-K-PGF1 alpha) following warm ischemia of the total canine liver were examined, and the protective effect of a TXA2 synthetase inhibitor was assessed. Total liver ischemia was performed for 60 min on two groups of dogs: a control group, in which ischemia alone was performed, and an OKY-046 group, which received a TXA2 synthetase inhibitor. A temporary active portacaval shunt was used to eliminate the effects of splanchnic venous stasis during clamping of the hepatic pedicle. Postoperative changes in liver function, assessed by the transaminase enzyme levels, and in prostaglandins were recorded and the histologic liver findings of both groups 1 week after ischemia were compared. The levels of 6-K-PGF1 alpha increased after reperfusion in both groups, while those of TXB2 increased in the control group but maintained low levels in the OKY-046 group. Liver function was better and histologic changes less marked in the OKY-046 group than in the control group, suggesting the important role of TXA2 in ischemic liver injury and the usefulness of a TXA2 synthetase inhibitor for protecting the liver against ischemic injury.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspartate Aminotransferases; Dogs; Ischemia; L-Lactate Dehydrogenase; Liver; Liver Function Tests; Liver Transplantation; Methacrylates; Organ Preservation; Reperfusion Injury; Thromboxane B2; Thromboxane-A Synthase

In a rat model, the left kidney was subjected to 60 min of normothermic ischemia followed by 15 min of reperfusion, whereas the right kidney, serving as a paired control, was not rendered ischemic. Both kidneys were then perfused in situ with either Euro-Collins (EC) solution (n = 12) or University of Wisconsin (UW) solution (n = 6) for 10 min. Each kidney was then harvested and stored at 4 degrees C in its respective solution. After 24 and 48 h of cold storage, the following vasoactive substances were measured in the preservation media: endothelin (ET), angiotensin II (A-II), thromboxane (B2) (TxB2), and prostaglandin I2 (PGI2). After 24 h in EC solution, left kidneys uniformly produced significantly higher concentrations of each vasoactive substance than right kidneys: ET 1.64 +/- 0.3 pg/ml vs 0.82 +/- 0.1 pg/ml (P < or = 0.009); A-II 20.8 +/- 6.2 pg/ml vs 7.75 + 2.3 pg/ml (P < or = 0.007); TxB2 100.8 +/- 17.7 pg/ml vs 40.1 +/- 11.7 pg/ml (P < or = 0.04); PGI2 638.3 +/- 41.1 pg/ml vs 318.3 +/- 36.4 pg/ml (P < or = 0.001), respectively. At 48 h, a similar pattern of results was obtained as the kidney continued to produce TxB2 and prostacyclins during the 24-48 h period. In the UW solution, basal levels of ET and A-II were lower than those in EC solution, but similarly increased after initial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine; Allopurinol; Angiotensin II; Animals; Cryopreservation; Endothelins; Glutathione; Humans; Hypertonic Solutions; Insulin; Ischemia; Kidney; Kidney Transplantation; Male; Organ Preservation; Organ Preservation Solutions; Radioimmunoassay; Raffinose; Rats; Rats, Wistar; Thromboxane B2

Bronchial arterial (BA) perfusion could modify pulmonary arterial (PA) ischemia-reperfusion (IR) injury by promoting clearance of peribronchial edema or limiting edema formation through maintenance of pulmonary vessel integrity via bronchopulmonary anastomotic or pulmonary vasa vasorum flow. The purpose of this study was to determine the effect of BA perfusion on IR injury in isolated sheep lungs. In 12 lungs (BA++) the BA was perfused throughout 30 min of PA ischemia and 180 min of reperfusion. In 12 lungs (BA-+) BA perfusion was begun with PA reperfusion, and in 15 lungs (BA--) the BA was never perfused. After 180 min, extravascular lung water was less (P < 0.05) in BA++ and B-+ lungs [4.70 +/- 0.16 and 4.57 +/- 0.18 g/g blood-free dry lung (bfdl)] than in BA-- lungs (5.23 +/- 0.19 g/g bfdl). The reflection coefficient for albumin was greater (P < 0.05) in BA++ and BA-+ (0.57 +/- 0.06 and 0.75 +/- 0.03) than in BA-- lungs (0.44 +/- 0.04). The filtration coefficient in BA++ and BA-+ lungs (0.016 +/- 0.006 and 0.015 +/- 0.006 g.min-1 x mmHg-1 x kg-1) was not different from that in BA-- lungs (0.025 +/- 0.006 g.min-1 x mmHg-1 x kg-1). These results suggest that BA perfusion decreased reperfusion edema by attenuating the increase in pulmonary vascular permeability caused by IR injury. Moreover the result in BA-+ lungs suggests that the protective effect was mediated by BA perfusion of PA vasa vasorum rather than bronchopulmonary anastomotic flow, which was trivial compared with PA blood flow.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Bronchi; Bronchial Arteries; Capillary Permeability; Extravascular Lung Water; Ischemia; Lung; Lymphatic System; Pulmonary Circulation; Pulmonary Edema; Regional Blood Flow; Reperfusion Injury; Respiration, Artificial; Sheep; Thromboxane B2; Water-Electrolyte Balance

Superoxide dismutase (SOD) is a potent scavenger of superoxide radicals produced during normothermic ischemia-reperfusion. Since it has a short half-life, its optimal effect is achieved when it is given prior to reperfusion. The inclusion of SOD in liposomes (lipo-SOD) prolongs its half-life (free SOD: 6 min; lipo-SOD: 4 h). The protective effect of lipo-SOD in a 60-min bilateral renal warm ischemia model was studied. We divided 60 male Wistar rats between two control groups and five study groups according to the drug used (SOD or lipo-SOD) and to the time of SOD administration (prior to ischemia or prior to reperfusion). SOD and lipo-SOD were both given at 20 mg/kg endovenously. Weight, diuresis, creatinine per 100 g (Cr/100 g), and creatinine clearance per 100 g (CrCl/100 g) were studied. Conventional renal histology was performed after reperfusion and on day 7. Renal malondialdehyde, 6 keto PGF 1 alpha, and TxB2 tissue levels were studied after reperfusion. Results showed that the renal protective effect of free SOD on warm ischemic-reperfusion injury depended on the time of administration, being more effective when given before reperfusion. On the other hand, the renal protective effect of liposomed SOD did not depend on the time of administration since efficacy was similar when given before reperfusion or before ischemia. The functional protective effect of liposomed SOD was similar to that of free SOD when they were given prior to reperfusion. Nevertheless, since histological damage observed with liposomed SOD was less than with free SOD, it is suggested that the liposomed galenic form may offer better protection against renal warm ischemia. In addition, liposomed SOD was better at preventing tissue prostanoid generation after renal warm ischemic-reperfusion injury than free SOD. We concluded that liposomed SOD shows a higher renal protective effect against warm ischemia than free SOD.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Creatinine; Drug Carriers; Free Radical Scavengers; Ischemia; Kidney; Liposomes; Male; Malondialdehyde; Rats; Rats, Wistar; Reperfusion; Reperfusion Injury; Superoxide Dismutase; Thromboxane B2

The purpose of this study is to observe the effect of electroacupuncture at "Taixi" point (KI-3) on the renal blood flow (RBF) under the condition of glycerol-induced renal ischemia and the changes of thromboxane A2 (TXA2) and prostacyclin (PGI2) during this course. The RBF, which is measured by hydrogen gas clearance method, was chosen as an index. The results are as follows: 1. After electroacupuncture at "Taixi" point, the RBF increased. 2. Under the condition of renal ischemia, the TXA2 increased, and the PGI2 decreased. 3. During the course of electroacupuncture at "Taixi" point, the TXA2 decreased and the PGI2 increased. These facts suggest that the effect of electroacupuncture at "Taixi" point is related to the PGI2 and the TXA2.

Topics: 6-Ketoprostaglandin F1 alpha; Acupuncture Points; Animals; Electroacupuncture; Female; Ischemia; Kidney; Male; Rabbits; Renal Circulation; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Ischemia; Isoquinolines; Liver; Male; Molecular Structure; Platelet Activating Factor; Pyridinium Compounds; Rats; Rats, Wistar; Tetrahydroisoquinolines; Thromboxane B2

The ability of brain preparations from 20-day-old rat fetuses to synthesize prostanoids in vitro before and after interruption of the maternal-fetal blood flow was examined using a radioimmunoassay technique. Synthesis of thromboxane B2 (TxB; the stable thromboxane A2 metabolite) decreased with increasing restriction time; conversely, it was elevated with reperfusion. Synthesis of 6-keto prostaglandin F1 alpha (PGF; the stable prostacyclin metabolite) and prostaglandin E2 (PGE) prostanoids remained unchanged after 20 min restriction and through a 2 hr reperfusion period. Intraperitoneal administration of GM1 (45 mg/kg) into the pregnant rat, 3 hr before restriction, stimulated synthesis of PGE and reduced synthesis of TxB. A prostanoid vasoactive index (PVI), which reflects the relative proportion of the three prostanoids synthesized and asserts the vasoactive potential of the brain tissue, was established. A rise in this value was attained after intrafetal administration into the peritoneal cavity of either GM1, GM3, or isopropyl-GM1 (AGF44) gangliosides, each given at 40 micrograms dose in 5 microliters volume, and N-dichloroacetyl-sphingosine (LIGA20; 15 micrograms/5 microliters) ganglioside analog, 1 hr before restriction. The effect was primarily due to an increase in the capacity of fetal brain tissue to synthesize PGE and, to a lesser extent PGF, vasodilating prostanoids. The N-methyl-D-aspartate (NMDA) receptor-blocker MK801 (6.6 micrograms/2 microliters) and the platelet activating factor (PAF) receptor antagonist BN52021 (0.1 mumol/2 microliters), given by the same route, effectively raised by 60-80% the vasodilating potential of the brain tissue following ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Brain; Dinoprostone; Dizocilpine Maleate; Female; Fetus; G(M1) Ganglioside; G(M3) Ganglioside; Gangliosides; Ischemia; Pregnancy; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Reperfusion; Thromboxane B2

To investigate the potential pathogenetic and therapeutic roles of thromboxane A2 (TXA2) and its receptor blockade, respectively, in the early phase of ischemic acute renal failure (ARF), renal function, TXB2 excretion, and the effects of the specific TXA2 receptor antagonist sulotroban (SU) in a model of unilateral renal artery occlusion in conscious female Sprague-Dawley rats were studied. Occlusion of the left renal artery for 1 h in untreated (i.e., vehicle-treated) rats (N = 8) resulted in oliguric ARF. In SU-treated rats (N = 8), the drug was given as an i.v. bolus of 5 mg/kg body wt, followed by a continuous infusion of 0.5 mg/min.kg body wt from 1 h before and during ischemia and for 6 h after reflow. After 1 h of ischemia, urine volume of left ischemic kidneys from untreated rats had decreased from 13.2 +/- 2.8 to 1.0 +/- 0.3 and 0.5 +/- 0.2 microL/min.100 g at 2 and 6 h of reflow, respectively, and GFR had decreased from 0.32 +/- 0.04 mL/min.100 g body wt to undetectable values. At 6 h of reflow, medullary Na-K-ATPase was slightly (P < 0.05) reduced in left ischemic kidneys, whereas medullary and papillary enzyme activities were compensatorily increased (P < 0.01) in right intact kidneys. The ADP/O ratio of cortical mitochondria was 41% (P < 0.05) and ATP synthesis was 77% (P < 0.01) lower than in right intact kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Kidney Injury; Adenosine Triphosphate; Animals; Calcium; Female; Ischemia; Kidney; Mitochondria; Oliguria; Rats; Rats, Sprague-Dawley; Receptors, Thromboxane; Sodium-Potassium-Exchanging ATPase; Sulfonamides; Thromboxane B2

Exposure of isolated perfused rabbit lungs (IPL) to ischemia-reperfusion causes a transient increase in pulmonary arterial (PA) pressure at the onset of reperfusion. Because thromboxane A2 (TxA2) is a potent vasoconstrictor, we hypothesized that it may contribute to the ischemia-reperfusion-induced pressor response. To evaluate this hypothesis, we exposed IPL perfused with a cell-free solution to 40 min of warm ischemia followed by reperfusion and measured perfusate immunoreactive thromboxane B2 (iTxB2) and 6-ketoprostaglandin F1 alpha (i6-keto-PGF1 alpha). We observed that ischemia-reperfusion IPL compared with controls had an increase in PA pressure (40.2 +/- 4.8 vs. 9.3 +/- 0.3 mmHg, P < 0.05), lung edema (29.3 +/- 6.3 vs. -0.2 +/- 0.2 g, P < 0.05), iTxB2 perfusate levels (155 +/- 22 vs. < 50 pg/ml, P < 0.05), and i6-keto-PGF1 alpha (436 +/- 33 vs. 61 +/- 16 pg/ml, P < 0.05). In ischemia-reperfusion IPL, infusion of SQ 29548 (10(-6) M), a specific TxA2/prostaglandin H2 receptor antagonist, attenuated the PA pressor response and the degree of edema. We conclude that pulmonary hypertension associated with ischemia-reperfusion results in part from pulmonary release of TxA2. Furthermore, TxA2 directly through membrane effects or indirectly through hydrostatic mechanisms increases the severity of ischemia-reperfusion-induced lung edema.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Pressure; Bridged Bicyclo Compounds, Heterocyclic; Fatty Acids, Unsaturated; Hydrazines; Hypertension, Pulmonary; In Vitro Techniques; Ischemia; Lung; Organ Size; Pulmonary Circulation; Pulmonary Edema; Rabbits; Radioimmunoassay; Receptors, Thromboxane; Reperfusion Injury; Thromboxane A2; Thromboxane B2; Thromboxanes; Vasoconstriction

Mesenteric ischemia stimulates both A delta- and C-fiber afferents to reflexly activate the cardiovascular system. Leukotriene B4 (LTB4) concentration is increased in intestinal mucosa following prolonged ischemia (3 h) followed by reperfusion. Because LTB4 sensitizes afferent nerve endings in the skin, we determined whether LTB4 is produced during brief mesenteric ischemia and thus would be present to sensitize afferent nerve endings in the abdominal visceral region. Cannulas were placed in the portal vein and in a mesenteric lymphatic vessel distal to the lymph node. Mesenteric lymph and portal venous immunoreactive LTB4 (iLTB4) and immunoreactive thromboxane B2 (iTxB2) concentrations were measured before, during, and after 5-7 min of ischemia induced by occlusion of the descending thoracic aorta in cats. Simultaneously, lymph and plasma lactate concentrations were measured. During arterial occlusion, femoral arterial pressure dropped to less than 30 mmHg, and portal venous and mesenteric lymph lactate concentrations were increased significantly (3.3 +/- 0.6 to 6.3 +/- 1.0 mM and 5.2 +/- 0.9 to 7.2 +/- 1.1 mM, respectively, P less than 0.05). During ischemia, iLTB4 concentration increased in lymph from 261 +/- 70 to 424 +/- 102 pg/0.1 ml (P less than 0.05) but did not increase in portal venous blood (135 +/- 26 vs. 168 +/- 44 pg/0.1 ml, control vs. ischemia). iTxB2 concentration was not increased during ischemia in either portal venous blood or lymph (12 +/- 4 to 24 +/- 9 pg/0.1 ml and 19 +/- 7 to 24 +/- 11 pg/0.1 ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cats; Intestinal Mucosa; Intestines; Ischemia; Leukotriene B4; Lymph; Osmolar Concentration; Portal Vein; Thromboxane B2; Time Factors

Topics: Animals; Ischemia; Liver Transplantation; Methacrylates; Swine; Temperature; Thromboxane B2; Thromboxane-A Synthase

Interleukin-1 and thromboxane are known to mediate the host response to sepsis, trauma, and myocardial ischemia. A well-established model of canine isolated gracilis muscle was used to evaluate whether cytokine (interleukin-1) played a role in skeletal muscle ischemia-reperfusion injury. Six adult mongrel dogs (25-30 kg) were subjected to six hours of muscle ischemia followed by reperfusion. Gracilis venous samples were collected pre-ischemia and at one hour of reperfusion. Systemic (arterial) blood samples were taken at one hour of reperfusion. Sera were analyzed for interleukin-1 by bioassay and thromboxane (B2) by radio-immunoassay. The gracilis muscle of the operated limb was harvested in all the animals for assessment of the percentage of muscle necrosis. This was found to be 56.2 +/- 14.8% by serial transections, nitroblue tetrazolium staining, and computerized planimetry. Interleukin-1 levels in the gracilis venous effluent increased from 21.88 +/- 7.13 units/ml during pre-ischemic baseline to 50.42 +/- 9.12 units/ml after six hours of ischemia followed by one hour of reperfusion (p less than 0.04). Thromboxane B2 levels were 2983 +/- 1083 pg/ml and 9483 +/- 2218 pg/ml at pre-ischemia and at one hour of reperfusion respectively (p less than 0.04). Systemic levels of both interleukin-1 and thromboxane B2 at one hour of reperfusion were 0 units/ml and 1584 +/- 520 pg/ml respectively, which were significantly lower than the one hour reperfusion gracilis venous effluent levels (p less than 0.04). This is the first report in which cytokines have been implicated in skeletal muscle ischemia-reperfusion injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Biological Assay; Disease Models, Animal; Dogs; Hindlimb; Interleukin-1; Ischemia; Muscles; Radioimmunoassay; Reperfusion Injury; Thromboxane B2

This study was carried out to investigate the proportion of the 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) and thromboxane B2 (TXB2) alteration that is due to ischemia in pancreas transplantation against the proportion due to reperfusion. For this purpose, Lewis rats were divided in three experimental groups: Group I = Control, Group II = Donor pancreas subjected to 15 minutes of cold ischemia, Group III = Same as group II but pancreas were transplanted to the recipient individual and then subjected to reperfusion. The results indicate that increases in pancreas 6-keto PGF1 alpha occur as a consequence of cold ischemia while TXB2 remains unchanged. When blood flow was restored, 6-keto PGF1 alpha remained unchanged compared to the ischemic group while pancreatic levels of TXB2 were significantly increased. These results suggest a different induction of prostanoid metabolism during ischemia and reperfusion in pancreatic tissue.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Ischemia; Male; Organ Preservation; Pancreas; Pancreas Transplantation; Rats; Rats, Inbred Lew; Reperfusion Injury; Thromboxane B2

Forty dogs were divided randomly into four groups. The portal circulation was reduced to 50%-60% for one hour by partially occluding the superior mesenteric artery (SMA) for the purpose of determining the relationship between the reperfusion injury, bacterial translocation, and multiple system organ failure. Escherichia coli 0111 B4 (1 x 10(10)/kg) was fed to each animal 12 hours before operation. Group I constituted the controls, in which a sham operation was done. The experimental procedure was completed in all the animals of the other three groups. The group-II animals received no further manipulation. Rubia yunnanensis, an antioxidant, was given to the animals in group III. Amikacin was given to the animals in group IV. The results showed that the animals in group II developed bacteremia, hypoxemia, and hypotension compared with the animals in group I. The levels of superoxide dismutase (SOD) in whole blood were markedly lowered in group-II animals, with malondialdehyde (MDA) values significantly elevated after reperfusion when compared with group I. Plasma levels of anaphylatoxin C5a and thromboxane B2 (TXB2) were significantly raised in group-II animals beginning from reperfusion when compared with the animals in group I, group III, and group IV. Pathologic changes in the intestine, liver, and lung were marked only in the group-II animals, including acute necrosis of the intestinal mucosa, granulocyte infiltration, and bacterial invasion of the liver and lung. These results suggested that bowel ischemia and reperfusion may promote gut barrier failure and bacterial translocation, then contribute to the development of MSOF by allowing bacteria or endotoxin normally contained within the gut to reach the portal and systemic circulations, where it fuels the septic process. Oxygen free radicals, anaphylatoxin, and thromboxane may be potential factors in the development of gut barrier failure and MSOF.

Topics: Animals; Bacteremia; Complement C5a; Dogs; Escherichia coli; Intestines; Ischemia; Malondialdehyde; Multiple Organ Failure; Reperfusion; Superoxide Dismutase; Thromboxane B2

1. The burst of damaging oxygen free-radicals at the time of reperfusion is one of the crucial factors affecting skin flap survival after an ischaemic interval. In these experiments the efficacy of the antioxidant and free-radical scavenger N-acetylcysteine in improving the survival of ischaemic rabbit epigastric skin flaps was tested. 2. At the time of reperfusion flaps were given: (1) balanced salt solution by intravenous whole-body administration, (2) N-acetylcysteine (200 mg/kg) by intravenous whole-body administration, (3) balanced salt solution by intra-arterial infusion into the flap, (4) N-acetylcysteine (20 mg/kg) by intra-arterial infusion into the flap, or (5) N-acetylcysteine (200 mg/kg) by intra-arterial infusion into the flap. Flap survival at 1 week, and tissue levels of parameters related to free-radical production, blood levels of thromboxane B2 and peripheral resistance during reperfusion were determined. 3. Compared with controls (groups 1 and 3) which had flap survival rates (expressed as percentage surface area surviving) of 27.1% and 31.6%, respectively. N-acetylcysteine treatment in group 2 (55.2%) and group 4 (51.9%) resulted in significant (P less than 0.05) improvements in flap survival. The survival rate in group 5 (37.7%) was not significantly better than that of the controls. 4. N-Acetylcysteine significantly reduced parameters related to free-radical production in the skin flap after 30 min of reperfusion, determined as tissue levels of malonyldialdehyde and protein oxidation products. There was also a significant decrease in peripheral resistance when low-dose N-acetylcysteine (group 4) was infused intra-arterially into the flap.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetylcysteine; Animals; Antioxidants; Disease Models, Animal; Free Radical Scavengers; Graft Survival; Ischemia; Malondialdehyde; Phenylhydrazines; Rabbits; Reperfusion Injury; Skin; Surgical Flaps; Thromboxane B2; Vascular Resistance

Derivatives of arachidonic acid have been found to play a role in the reperfusion injury of various tissues. These compounds have a broad spectrum of activity, including modulation of white blood cell response to injured tissue. This study was designed to determine the effect of thromboxane and lipoxygenase derivatives on the local and systemic response to ischemia and reperfusion of skeletal muscle. Fifteen dogs were separated into three groups and subjected to gracilis muscle ischemia followed by 2 hours of reperfusion. One group served as controls, one group was treated with OKY-046 (a thromboxane synthetase inhibitor), and one group was treated with diethylcarbamazine (a lipoxygenase inhibitor). White blood cell activation as measured by superoxide anion production, and eicosanoid levels were measured both in the gracilis venous effluent and central venous circulation. These results were compared to infarct size in the gracilis muscle. OKY-046 significantly reduced thromboxane production in both the central venous (102 +/- 30 to 31 +/- 9 pg/ml, p less than 0.05) and gracilis samples (107 +/- 22 to 25 +/- 6 pg/ml, p less than 0.005). This was accompanied by a reduced white cell activation in the central venous blood (15 +/- 1 to 10 +/- 1 nmol O2-, p less than 0.05), but did not affect infarct size or white cell activation in the gracilis. Conversely, diethylcarbamazine significantly reduced both white cell activation (16 +/- 1 to 10 +/- 1 nmol O2-, p less than 0.005) and infarct size in the gracilis muscles (61.6% +/- 4.5% to 28.5% +/- 8.6%, p less than 0.01), as well as reduced systemic white blood cell activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acids; Cell Survival; Diethylcarbamazine; Dogs; Female; Ischemia; Leukotriene B4; Male; Methacrylates; Muscles; Neutrophils; Reperfusion Injury; Superoxides; Thromboxane B2; Thromboxane-A Synthase

The purpose of this study was to evaluate the role of arachidonic acid metabolites in the reimplantation response after lung transplantation in mongrel dogs. The left lung was used and two groups were studied. Group I underwent hilar stripping, while Group II underwent hilar stripping plus warm ischemia for 60 min., achieved by clamping the left pulmonary artery and veins. We measured the lung wet to dry weight ratio (W/D ratio), total pulmonary vascular resistance (TPVR), and blood and bronchoalveolar lavage fluid (BALF) levels of leukotriene B4 and C4 (LTB4,C4) and thromboxane B2 (TXB2). These parameters were measured periodically for 7 days after reperfusion. In group II, the W/D ratio and TPVR were significantly increased in comparison with Group I. The blood LTC4 level was elevated immediately after reperfusion, and BALF level of LTC4 also rose subsequently. These levels changed concomitantly with the W/D ratio. The above results suggest that arachidonic acid metabolism plays an important role in the reimplantation response, especially in pulmonary edema.

Topics: Animals; Arachidonic Acid; Bronchoalveolar Lavage Fluid; Dogs; Ischemia; Leukotriene B4; Lung; Lung Transplantation; Pulmonary Edema; Reperfusion; SRS-A; Thromboxane B2

Ischemic injury is characterized by neutrophil (PMN)--endothelial cell adhesion and diapedesis associated with thromboxane (TX) generation. Neutrophil-endothelial cell interaction is regulated in part by the leukocyte adhesion receptor CD 18 glycoprotein complex and the endothelial intercellular adhesion molecule-1 (ICAM-1). This study tests the role of TX in ischemia-induced diapedesis and evaluates whether the diapedesis is regulated by neutrophil or endothelial adhesion receptors. Plasma derived from rabbit hind limbs made ischemic for 3 hours (n = 6) and reperfused for 10 minutes had increased levels of TXB2 3,450 pg/ml, which was higher than sham rabbit (n = 6) values of 653 pg/ml (p less than 0.05). When introduced into abraded skin chambers placed on the dorsum of other normal rabbits (n = 6), this ischemic plasma induced 1,000 pg/ml of new TX synthesis and diapedesis of 1,235 PMN/mm3. The total TX concentration and PMN accumulations in blister fluid were correlated (r = 0.88, p less than 0.05). In contrast, sham rabbit plasma induced no TX synthesis and diapedesis of only 77 PMN/mm3 (p less than 0.05). Administration of 50 ng/ml of authentic TXB2 into blisters induced an accumulation of 453 PMN/mm3, which was higher than that in saline controls (18 PMN/mm3) (p less than 0.05). Pretreatment of normal rabbits used for the diapedesis assay (n = 4) with the TX synthetase inhibitor OKY 046 (2 mg/kg/hr) limited ischemic plasma and authentic TXB2 induced diapedesis to 142 and 76 PMN/mm3, respectively (both p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Capillaries; CD18 Antigens; Cell Adhesion Molecules; Dactinomycin; Endothelium, Vascular; Fatty Acids, Unsaturated; Hydrazines; Intercellular Adhesion Molecule-1; Ischemia; Male; Methacrylates; Muscles; Neutrophils; Rabbits; Receptors, Leukocyte-Adhesion; Reference Values; Regional Blood Flow; Reperfusion; Skin; Thromboxane B2; Thromboxane-A Synthase; Thromboxanes

We investigated the role of complement activation on the resolution of acute ischemic renal failure in the rat. Acute renal failure was induced by clamping of the renal arteries of Sprague-Dawley rats for 45 minutes (Day 0). On subsequent days, groups of rats with acute renal failure were exposed to daily zymosan infusion (an activator of the complement system), or to blood incubated with cuprophane (CUP) or polyacrylonitrile (PAN) dialysis membranes. We serially measured the change in BUN daily, glomerular filtration rate and 24-hour proteinuria on Day 3 and Day 5 following ischemia. On Day 6, the animals were sacrificed and their kidneys examined histologically. Zymosan and cuprophane exposed rats had a significant delay in the recovery of renal failure, reduced glomerular filtration rate, and histologically had more neutrophil infiltration than control or PAN exposed animals. To investigate the potential pathophysiology of these observations, we assessed the response of zymosan-exposed rats to infusion of deferoxamine (DFO), a potent inhibitor of hydroxyl radical formation (OH.). Infusion of DFO prior to zymosan significantly improved recovery of renal function. We also measured urinary thromboxane B2 levels in these groups of rats. While the groups of rats exposed to zymosan had the highest levels of thromboxane B2, these levels were not different between the groups exposed to zymosan alone, or to zymosan and DFO. These observations suggest a role for hydroxyl radicals in the prolongation of renal failure in this model. Taken together, these findings may have implications for the dialytic intervention in patients with acute renal failure.

Topics: Acute Kidney Injury; Animals; Cellulose; Complement Activation; Free Radicals; Ischemia; Kidney; Male; Oxygen; Rats; Renal Dialysis; Thromboxane B2; Zymosan

Platelet aggregation (PA) induced by ADP, collagen and epinephrine, plasma levels of beta-thromboglobulin (beta TG) and thromboxane B2 (TXB2) and serum TXB2 generation were studied in 11 patients with primary thrombocytosis (7 with essential thrombocythaemia and 4 with polycythaemia vera) and compared with 16 healthy subjects. 5 patients suffered from peripheral vascular ischaemia and another 3 had venous thrombosis, but none had bleeding complications. The patients showed an abnormal pattern of platelet function and of thromboxane generation distinct from the healthy subjects in three aspects. a) Shape change was 5-26 times greater, the lag-time of collagen PA was 2.3-2.9 times longer and the extent of epinephrine PA was nil or very low. ADP- or collagen-induced PA was also reduced (p less than 0.02). b) Plasma TXB2 generation (corrected to a normal platelet concentration) stimulated by the three PA inducers was within the range of the healthy subjects in spite of the reduced extent of PA. c) Plasma beta TG level and serum TXB2 generation (both corrected to a normal platelet concentration) were 2.9-7.1 times higher (p less than 0.001) indicating enhanced in vivo platelet activation and possibly increased thrombin generation. These abnormalities were not detected in another 4 patients with secondary thrombocytosis. The abnormal pattern of platelet function and thromboxane generation can be a useful laboratory method in the evaluation of patients with primary thrombocytosis. It might also explain the thrombotic complications which occurred in 8 of the patients in a manner such that increased or normal TXB2 generation overcomes the reduced extent of PA. In this respect, the pronounced serum TXB2 synthesis might be a marker of intravascular thrombosis.

Topics: beta-Thromboglobulin; Female; Humans; Ischemia; Male; Middle Aged; Platelet Aggregation; Thrombocytosis; Thrombosis; Thromboxane B2

Ischemia of the lower extremity has been shown to cause pulmonary leukostasis and increased pulmonary artery pressure. Thromboxane (TX) has been implicated as a mediator in this process. The effect of OKY-046, a TX synthetase inhibitor, on polymorphonuclear leukocyte (PMN) production of superoxide anion (O2-) as determined by ferricytochrome reduction was examined. Fourteen dogs were subjected to 6 hours of bilateral gracilis muscle ischemia followed by 1 hour of reperfusion. O2- production from resting PMNs and PMNs stimulated with opsonized zymosan (OZ, 0.1 mg/ml) was measured prior to ischemia or drug treatment (baseline), and following reperfusion in both treated (n = 7) and control groups (n = 7). Serum TX levels were measured using a radioimmunoassay. Following reperfusion, TX levels in the treated group were decreased as compared with the control group (18 +/- 2 pg/ml vs. 72 +/- 26 pg/ml, P less than 0.05). Superoxide production by both resting and stimulated PMNs was also decreased in the treated group; from 0.98 +/- 0.16 nmol to 0.43 +/- 0.12 nmol O2- in the resting state (P less than 0.05) and from 13.3 +/- 1.5 nmol to 9.0 +/- 1.1 nmol O2- after stimulation (P less than 0.005). O2- production was increased in the control group following reperfusion as compared with baseline samples, and this increase was attenuated by treatment with OKY-046. TX synthetase inhibition decreases activation of PMNs following hindlimb ischemia.

Topics: Animals; Dogs; Female; Injections, Intravenous; Ischemia; Leg; Lung Diseases; Lymphocyte Activation; Male; Methacrylates; Neutrophils; Superoxides; Thromboxane B2; Thromboxane-A Synthase

1. Biochemical mechanisms of ischaemia were investigated in rabbit skin flaps subjected to 2 h of primary ischaemia then, 24 h later, to 4 h of secondary ischaemia. During secondary ischaemia, flaps underwent either total ischaemia (arterial and venous blood supply occluded) or partial ischaemia (vein only occluded). Some of these flaps were treated at the time of reperfusion with the free-radical scavenger superoxide dismutase (EC 1.15.1.1) and/or the thromboxane synthetase inhibitor UK-38,485. 2. After 30 min of reperfusion, superoxide dismutase treatment significantly reduced blood thromboxane levels, elevated during ischaemia. Superoxide dismutase also reduced tissue levels of malonyldialdehyde and xanthine oxidase, indicators of free-radical damage, and restored the depleted tissue levels of superoxide dismutase. 3. UK-38,485 treatment failed to significantly alter any of these tissue free-radical parameters, although this agent significantly reduced blood thromboxane levels. 4. Combined superoxide dismutase plus UK-38,485 treatment was not significantly better than either treatment alone with respect to any parameter. 5. Partial ischaemia led to consistently higher levels of tissue free radicals and blood thromboxane than did total ischaemia. Thus partial ischaemia appears to result in greater free-radical damage than total ischaemia. 6. These results are consistent with the hypothesis that thromboxane acts as a mediator for free-radical damage in the ischaemic changes within the flap.

Topics: Animals; Free Radical Scavengers; Free Radicals; Imidazoles; Ischemia; Rabbits; Reperfusion Injury; Skin; Surgical Flaps; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

The effects of DP-1904, a thromboxane (TX) A2 synthase inhibitor, on renal function were investigated by analysis of prostanoid metabolism in hydronephrotic and ischemic rat kidney models, and in isolated perfused normal and hydronephrotic rat kidneys. The increase in production of TXB2 in hydronephrotic or ischemic kidneys was significantly suppressed by intraperitoneal DP-1904 (10 mg/kg), with the 6-keto-prostaglandin F1 alpha to TXB2 ratio being significant increased. Urine volume, glomerular filtration rate and renal plasma flow were all improved. DP-1904 (0.3 micrograms/min) blocked the effects of infused arachidonic acid on isolated perfused normal rat kidneys thus reducing TXB2 levels and perfusion pressure but the pressor response to norepinephrine or angiotensin II remained unchanged. In isolated perfused hydronephrotic rat kidneys, DP-1904 suppressed the increase in perfusion pressure and TXB2 production caused by platelet-activating factor. These findings suggested that DP-1904 improved renal failure by specifically inhibiting TXA2 production.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Kidney Injury; Animals; Hydronephrosis; Imidazoles; Ischemia; Kidney; Male; Perfusion; Rats; Rats, Inbred Strains; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

Renal vasoconstriction and ischaemia that follow in vitro antigen challenge of isolated perfused kidney of sensitized guinea-pig appears to be a self-perpetuating process, starting with a primary peak of release of vasoconstrictor mediators and followed by secondary peaks (particularly of arachidonic acid metabolites) which are probably initiated by ischaemia/reperfusion damage.

Topics: Animals; Antigens; Blood Pressure; Guinea Pigs; Histamine Release; In Vitro Techniques; Ischemia; Kidney; Ovalbumin; Renal Circulation; SRS-A; Thromboxane B2; Vasoconstriction

A hyperdynamic sepsis model was developed in dogs. It is based on a 3-hour clamping of the arteries supplying the middle portion of the jejunum. The ensuing sepsis has a course of several days, during which the animals were studied in the conscious state. 2/3 of the animals developed a sustained 32-108 per cent increase in cardiac output, and survived 7 days or more. In the other 1/3 of the animals, the cardiac output was lower than the control value and all these animals died within 5 days. There were no differences between the two groups in other parameters examined. Sepsis caused a steady, slight decrease in mean arterial pressure, an increase in heart rate, and leukocytosis. The plasma levels of epinephrine and norepinephrine showed a sustained, significant elevation. The level of thromboxane B2 was high only on the first day of sepsis, and that of plasma renin activity on the first 2 days. Necrosis and edema of jejunal villi were demonstrated histologically in the early period. Hemocultures were positive in only 5 of 11 animals examined, suggesting the predominant role of absorbed toxins. This model simulates human sepsis well and is suitable for the study of pathophysiologic mechanisms in hyperdynamic sepsis.

Topics: Alkaline Phosphatase; Animals; Bacterial Infections; Blood Pressure; Cardiac Output; Disease Models, Animal; Dogs; Epinephrine; Female; Heart Rate; Hematocrit; Hemodynamics; Ischemia; Jejunum; Leukocyte Count; Male; Norepinephrine; Renin; Thromboxane B2

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Cold Temperature; Dinoprostone; Erythrocytes; Hypertonic Solutions; Ischemia; Kidney Cortex; Kidney Medulla; Kidney Transplantation; Male; Organ Preservation; Rats; Rats, Inbred Lew; Reperfusion; Superoxide Dismutase; Thromboxane B2; Transplantation, Isogeneic

Thromboxane, prostacyclin and their ratio could play an important role in the ischemic liver injury. To study this hypothesis, thromboxane and prostacyclin were measured by RIA after incubation of liver tissues removed during and after an ischemia of 90 min in male Wistar rats. The thromboxane to prostacyclin ratio increases during this period. In order to examine if this change could influence the survival rate of animals submitted to the same period of ischemia, drugs able to reduce the relative predominance of thromboxane were infused. The survival rate was not modified by administration of Iloprost or Daltroban, the antagonist of the thromboxane receptors. By contrast, imidazole, an inhibitor of thromboxane synthetase, significantly increased the survival rate. The same result was obtained with the administration of Daltroban plus Iloprost, suggesting that the reduction of thromboxane action associated with the increase of PGI2 level reduces the ischemic injury.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Epoprostenol; Iloprost; Imidazoles; Ischemia; Liver; Male; Phenylacetates; Rats; Rats, Inbred Strains; Sulfonamides; Thromboxane B2

Indirect evidence exists that the reperfusion of ischemic tissue activates white blood cells. Thus local and systemic reperfusion injuries are prevented by making animals leukopenic or by inhibiting white blood cell lung entrapment by blocking thromboxane A2 generation. This study tests directly whether ischemia and reperfusion activates neutrophils, as measured by their oxidative burst, and whether thromboxane mediates this event. Anesthetized rats underwent 4 hours of bilateral hind limb tourniquet ischemia followed by 60 minutes of reperfusion. Plasma thromboxane B2 levels increased to 2750 pg/ml at 5 minutes of reperfusion, higher than the sham control (n = 36) value of 370 pg/ml (p less than 0.01). In untreated ischemic animals (n = 30) the intracellular H2O2 production of circulating neutrophils, as assayed flow cytometrically by dichlorofluorescein oxidation, increased from a preischemic value of 133 to a peak of 251 femtomoles dichlorofluorescein/neutrophil at 5 minutes of reperfusion (p less than 0.01). Treatment of neutrophils with phorbol myristate acetate (PMA) 10(-7) mol/L led to a 91% increase in neutrophil H2O2 production before ischemia, and 5 minutes after reperfusion there was an enhanced response to PMA of 222% (p less than 0.01). Pretreatment of animals with the thromboxane-synthetase inhibitor OKY 046 (n = 36) prevented ischemia-induced thromboxane generation, neutrophil H2O2 production (p less than 0.05), as well as the enhanced response to PMA stimulation (p less than 0.05). Treatment with the thromboxane-receptor antagonist SQ 29,548 (n = 36) did not affect the increase in plasma thromboxane levels after ischemia but was as effective as OKY 046 in preventing the ischemia-induced increase in neutrophil H2O2 production and the enhanced response to PMA stimulation. These data indicate that lower-torso ischemia leads to neutrophil activation, manifest by H2O2 production, an event mediated by thromboxane.

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Fatty Acids, Unsaturated; Flow Cytometry; Hindlimb; Hydrazines; Hydrogen Peroxide; Ischemia; Male; Methacrylates; Neutrophils; Oxidation-Reduction; Rats; Rats, Inbred Strains; Receptors, Prostaglandin; Receptors, Thromboxane; Reperfusion; Thromboxane B2; Thromboxane-A Synthase; Thromboxanes

Lower torso ischemia leads during reperfusion to leukocyte (white blood cell)-dependent lung injury. This study tests the intermediary role of oxygen free radicals (OFRs) in mediating this event. Chronically instrumented anesthetized sheep underwent 2 hours of bilateral hindlimb ischemia. In untreated control animals (n = 7), 1 minute after tourniquet release, mean pulmonary artery pressure rose from 13 to 38 mm Hg (p less than 0.05), whereas pulmonary artery wedge pressure was unchanged from 4 mm Hg. The pulmonary hypertension was temporally related to an increase in plasma thromboxane (Tx) B2 levels from 211 to 735 pg/ml (p less than 0.05). At 30 minutes of reperfusion lung-lymph TxB2 levels rose from 400 to 1005 pg/ml (p less than 0.05). This coincided with an increase in lung-lymph flow from 4.3 to 8.3 ml/30 min (p less than 0.05), which remained elevated for 2 hours, an unchanged lymph/plasma protein ratio, and a rise in lymph protein clearance from 2.6 to 4.6 ml/30 min (p less than 0.05). These changes are consistent with increased lung microvascular permeability. White blood cell count fell during the first hour of reperfusion from 6853 to 3793/mm3 (p less than 0.05), and lung histologic findings showed marked leukosequestration relative to sham animals (n = 3). Pretreatment with the OFR scavengers, superoxide dismutase and catalase both conjugated to polyethylene glycol (n = 6) blunted the rise in mean pulmonary artery pressure to 19 mm Hg (P less than 0.05) and prevented the increase in plasma and lymph TxB2 lymph flow, and lymph protein clearance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Allopurinol; Animals; Catalase; Female; Free Radicals; Hemodynamics; Hindlimb; Ischemia; Leukocyte Count; Lung; Neutrophils; Platelet Count; Sheep; Superoxide Dismutase; Superoxides; Thromboxane B2

Neutrophils have been implicated as central mediators in myocardial and skeletal muscle ischemia-reperfusion injury. This study tests whether these cellular elements and the chemoattractant leukotriene (LTB4) play a role in postischemic renal failure. Anesthetized rats underwent 45 min of left renal pedicle clamping. Five minutes after reperfusion, LTB4 levels were elevated to 1.42 ng/ml (P less than 0.05); thromboxane (Tx)B2 was 2,840 pg/ml, higher than 503 pg/ml in sham controls (P less than 0.05); renal artery blood flow was 67% of preclamping values at 1 min of reperfusion compared with 111% in sham (P less than 0.05). At 24 h, creatinine levels were 4.6 mg/dl (P less than 0.05). At 24 h, creatinine levels were 4.6 mg/dl (P less than 0.05); histology showed acute tubular necrosis (ATN). Neutrophil depletion by rabbit antiserum (n = 8) led during reperfusion to reduced LTB4 and TxB2 levels, 1.04 ng/ml and 1.043 pg/ml (P less than 0.05); increased renal blood flow of 174% (P less than 0.05); reduced creatinine levels of 1.8 mg/dl (P less than 0.05); and limited ATN. Pretreatment with diethycarbamazine prevented the increases in LTB4 and TxB2 (P less than 0.05), increased renal blood flow (P less than 0.05), minimized creatinine increase to 1.7 mg/dl (P less than 0.05), and reduced ATN. These data indicate that neutrophils and LTB4 play a role in ischemia-induced Tx synthesis and mediate postischemic renal injury.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Diethylcarbamazine; Ischemia; Kidney; Leukocyte Count; Leukotriene B4; Male; Neutrophils; Rats; Rats, Inbred Strains; Renal Circulation; Renal Veins; Reperfusion; Thromboxane B2

Ischemia-induced renal injury is prevented by inhibition of thromboxane (Tx) synthesis. This protection was believed to be secondary to a high prostaglandin (PG)/TxA2 ratio. This study tests whether increasing the PG/Tx ratio by administration of vasodilating PGs protects the reperfused ischemic kidney. Anesthetized rats underwent right nephrectomy and 45 minutes of left renal pedicle clamping. Beginning 10 minutes before clamp release, animals were treated intravenously with the following: saline placebo (n = 10); the cyclooxygenase inhibitor ibuprofen (Ibu), 12.5 mg/Kg in a bolus (n = 8); a stable analogue of prostacyclin (PGI2), 500 ng/kg/minute for 2 hours (n = 9); PGE1, 400 ng/kg/minute for 2 hours (n = 8); the combination Ibu and PGI2 (n = 8) or PGE1 (n = 8). In saline treated ischemic controls, 5 minutes after reperfusion plasma, thromboxane (TxB2) and 6-keto-PGF1 levels were 2537 and 317 pg/ml, respectively--higher than the TxB2 and 6-keto-PGF1 levels of 750 and 80 pg/ml, respectively, in nephrectomized but nonischemic sham controls (n = 7) (p less than 0.05). In ischemic control animals at 24 hours, creatinine levels were 4.6 mg/dl, relative to 0.9 ml/dl in sham animals (p less than 0.05); the weight of the left (L) ischemic kidney relative to the right (R) normal kidney was 118%, compared with 99% in sham animals (p less than 0.05); and renal histology of ischemic control animals at 24 hours showed acute tubular necrosis (ATN) relative to normal findings in sham animals. Pretreatment with Ibu led to: TxB2 and 6-keto-PGF1 levels of 116 and 40 pg/ml, lower than those of sham animals (p less than 0.05); creatinine levels of 4.6 mg/dl, L/R renal weight of 119%; and ATN similar to that of ischemic controls. Treatment with a PGI2 analogue or PGE1 was not protective and led to increases in TxB2, 6-keto-PGF1, creatinine, L/R renal weight, and ATN similar to that of ischemic controls. The combination of Ibu and either PGI2 or PGE1 led to: reduced levels of TxB2 and 6-keto-PGF1 (p less than 0.05); attenuated increases in creatinine to 2.2 and 2.3 mg/dl, respectively (p less than 0.05); and limited ATN (p less than 0.05). These data indicate that the vasodilating PG protect the ischemic reperfused kidney only when Tx is inhibited.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Kidney Injury; Animals; Creatinine; Disease Models, Animal; Drug Combinations; Drug Evaluation, Preclinical; Epoprostenol; Ibuprofen; Ischemia; Kidney; Male; Organ Size; Prostaglandins E; Rats; Rats, Inbred Strains; Thromboxane B2; Vasodilator Agents

A persisting incidence of acute renal failure has been observed after operative treatment of thoracoabdominal aortic aneurysm, ruptured abdominal aortic aneurysm and renal artery occlusive disease in patients with preoperative impairment of renal function. Because preservation of kidney function can play an important role in the outcome of these patients, the effects of prostaglandin E1 (PGE1) to prevent ischaemic renal failure were studied in an experimental model. Twenty dogs were exposed to 3 h warm ischaemia by clamping of the supra- and infrarenal aorta and both renal arteries. In 10 dogs PGE1 was given intravenously (100 ng/kg/min) for 15 min before clamping. Ten dogs treated with normal saline served as controls. Glomerular filtration rate, renal plasma flow, plasma creatinine, blood urea nitrogen, urine volume, free water clearance and renovascular resistance were calculated before and after renal ischaemia for both groups. The dogs were followed-up for 2 weeks and radionuclide studies with Tc-99m-MAG3, I-131-OIH and In-113m-DTPA were performed on the third postoperative day to calculate global and split renal clearance, tracer extraction fraction and mean transport time. After renal ischemia 9 dogs of the control group and 3 dogs of the PGE1-group developed acute renal failure (P less than 0.05 due to Fisher's exact text). PGE1 infusion significantly attenuated the postischaemic fall in glomerular filtration rate and renal concentrating ability as well as the postischaemic increase of plasma creatinine and blood urea nitrogen induced by 3 h warm renal ischaemia (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Kidney Injury; Alprostadil; Animals; Awards and Prizes; Blood Urea Nitrogen; Disease Models, Animal; Dogs; Europe; Female; Glomerular Filtration Rate; Ischemia; Kidney; Kidney Concentrating Ability; Radionuclide Imaging; Renin; Societies, Medical; Thromboxane B2; Vascular Resistance; Vascular Surgical Procedures

Our previous studies indicate that the blockade of the sympathetic nervous system by spinal anesthesia or epidural anesthesia inhibits the release of TXA2 induced by limb ischemia with thigh tourniquet in patients with lower limb surgery. The present study was undertaken to confirm this phenomenon in anesthetized dogs. Twenty one anesthetized dogs underwent 60 min occlusion of the abdominal aorta and the inferior vena cava, followed by reperfusion. They were randomized into three groups: no treatment group and pretreatment groups with either 2 ml of 0.5% bupivacaine intrathecally or 4 mg.kg-1 of labetalol intravenously. In no treatment group plasma TXB2 levels were increased significantly after reperfusion. However, prior treatments with bupivacaine intrathecally or labetalol intravenously inhibited the increases in plasma TXB2 levels after reperfusion. These results suggest that limb ischemia stimulates the TXA2 production, which may be influenced not only by endothelial cell damage and the generation of oxygen free radicals but also by the activation of the sympathetic nervous system.

Topics: Animals; Bupivacaine; Dogs; Ischemia; Labetalol; Leg; Sympathetic Nervous System; Thromboxane A2; Thromboxane B2

The physiological factors that allow for the survival of ischemic skin flaps have not been clearly elucidated. Previous work by others has shown that elevation of a flap 24 hours before an episode of complete ischemia significantly improved survival, presumably by delaying the onset of the no-reflow phenomenon. The current study, using an epigastric flap, investigated the role of thromboxane in these events by observing postischemic plasma levels of thromboxane B2, the stable metabolite of the short-lived thromboxane A2. Acutely ischemic flaps were compared with those elevated 24 hours before ischemia. After the ischemic insult, blood was drawn from the venous effluent of the flaps. Thromboxane levels after 4 hours of ischemia were significantly decreased (p less than 0.001) in the postischemic period in those flaps elevated 24 hours before ischemia compared with flaps that had undergone ischemia acutely. Moreover, acutely ischemic flaps had significantly more thromboxane than nonischemic controls (p less than 0.001). These results confirm the importance of thromboxane metabolism in the no-reflow phenomenon.

Topics: Animals; Ischemia; Rabbits; Radioimmunoassay; Skin; Surgical Flaps; Thromboxane B2; Time Factors

Topics: Animals; Cerebrovascular Disorders; Disease Models, Animal; Edema; Ischemia; Male; Motor Activity; Prostaglandins; Rabbits; Reperfusion; Spinal Cord; Thromboxane B2

The impending no-reflow (NRF) state was studied in the rat hindlimb to identify possible biochemical mediators producing the no-reflow phenomenon. After 5 hours of ischemia, the venous effluents draining the ischemic limb and the contralateral nonischemic limb were collected for three 30-minute time periods. Thromboxane B2 (TxB2), prostaglandin E2 (PGE2), and 6-ketoprostaglandin F1 alpha, the stable metabolite of prostacyclin (PGI2), were measured by radioimmunoassay. Venous outflow rate, distal skin perfusion assessed by dermofluorometry, and histology of muscle and skin were examined in control limbs, ischemic limbs, and limbs with impending no reflow. The no-reflow state was characterized by a significantly decreased venous outflow (less than 0.01 ml per minute), decreased skin perfusion (index of fluorescence of 15 percent in no-reflow limbs versus 70 percent in reflow limbs), and absence of thrombosis of the vasculature. The no-reflow state also was associated with 2.4 times more thromboxane B2 and 1.5 times more 6-ketoprostaglandin F1 alpha than that observed in ischemic limbs with reflow. The biosynthesis of vasodilating prostaglandin E2 in the no-reflow state, however, was only 40 percent of the prostaglandin E2 measured in limbs with reflow. We propose that the impending no-reflow state may reflect a state of global microcirculatory "agonal" vasoconstriction, most probably due to an overabundant release of the vasoconstrictor thromboxane relative to the vasodilating prostaglandin E2 and prostacyclin. The likelihood of specific biochemical mechanisms producing the no-reflow state suggests that pharmacologic agents may be able to reverse the impending no-reflow state to improve tissue survival.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Flow Velocity; Dinoprostone; Hematocrit; Hindlimb; Ischemia; Prostaglandins; Prostaglandins E; Rats; Rats, Inbred Strains; Regional Blood Flow; Skin; Thromboxane B2; Time Factors; Vasomotor System; Veins

This study tests the role of white blood cells (WBC) and leukotrienes in mediating the increased microvascular permeability following ischemia and reperfusion. Anesthetized dogs (n = 23) underwent 2 hours of hind limb ischemia induced by tourniquet inflation to 300 mmHg. In untreated animals (n = 7), tourniquet release led after 5 minutes to a rise in plasma thromboxane (Tx) B2 levels from 360 to 1702 pg/ml (p less than 0.05); after 2 hours, lymph TxB2 concentration had risen from 412 to 1598 pg/ml (p less than 0.05). There were decreases in circulating WBC from 11,766 to 6550/mm3 and platelets from 230 to 155 x 10(3)/mm3. During reperfusion, popliteal lymph flow (QL) increased from 0.07 to 0.24 ml/hour (p less than 0.05), while the lymph/plasma (L/P) protein ratio was unchanged from 0.39, changes consistent with increased microvascular permeability. WBC depletion (n = 7) to 302/mm3 by hydroxyurea or nitrogen mustard attentuated (p less than 0.05) the reperfusion induced rise in plasma TxB2 from 91 to 248 pg/ml and prevented the increase in lymph TxB2 concentration. Within 5 minutes of tourniquet release WBC counts further decreased to 191/mm3 (p less than 0.05) and platelets declined from 175 to 93 x 10(3)/mm3 (p less than 0.05). QL increased from 0.07 to 0.12 ml/hour (p less than 0.05), lower than untreated animals (p less than 0.05), and the L/P protein ratio declined from 0.49 to 0.37 (p less than 0.05), dilutional changes consistent with increased filtration pressure but not permeability to protein. Pretreatment with the lipoxygenase inhibitor diethylcarbamazine (DEC) (n = 8) prevented the reperfusion-induced increase in plasma and lymph TxB2 levels (p less than 0.05) and the fall in WBC counts (p less than 0.05), while platelet counts declined from 381 to 210 x 10(3)/mm3 (p less than 0.05). QL rose from 0.09 to 0.23 ml/hour (p less than 0.05) during reperfusion, and the L/P protein ratio of 0.3 remained unchanged, a value lower than in untreated dogs (p less than 0.05). In two animals of each group, vascular recruitment was induced by tourniquet inflation to 50 mmHg. This led to a high QL of 0.25 ml/hour and a low L/P ratio of 0.18. In untreated animals during reperfusion, QL further increased to 1.3 ml/hour, and L/P ratio rose to 0.44, documenting increased vascular permeability. In contrast, reperfusion in leukopenic or diethylcarbamazine (DEC)-treated dogs with vascular recruitment, was not associated with increases in QL or the L/P protein ratio

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Capillary Permeability; Diethylcarbamazine; Dogs; Hindlimb; Ischemia; Leukocyte Count; Leukocytes; Leukotrienes; Lymph; Platelet Count; Reperfusion Injury; Thromboxane B2

Lower torso ischemia leads on reperfusion to sequestration of polymorphonuclear leukocytes (PMN) in the lungs and increased permeability. This study tests the role of circulating leukocytes (WBC) in mediating this lung injury. Anesthetized sheep prepared with chronic lung lymph fistulae underwent 2 hours of bilateral hind limb tourniquet ischemia. In untreated controls (n = 7), 1 minute after reperfusion there were transient increases in mean pulmonary arterial pressure (MPAP) from 13 to 38 mmHg (p less than 0.05) and pulmonary microvascular pressure (Pmv) from 7 to 18 mmHg (p less than 0.05), changes temporally related to a rise in plasma thromboxane (Tx) B2 levels from 211 to 735 pg/ml (p less than 0.05). Lung lymph TxB2 levels rose from 400 to 1005 pg/ml at 30 minutes (p less than 0.05), and remained elevated longer than plasma levels. Lung lymph flow (QL) rose from 4.3 to 8.3 ml/30 minutes (p less than 0.05) after 30 minutes of reperfusion and remained elevated for 2 hours. The lymph/plasma (L/P) protein ratio was unchanged from 0.6, while the lymph protein clearance increased from 2.6 to 4.6 ml/30 minutes (p less than 0.05), suggesting increased microvascular permeability. WBC counts decreased within the first hour of reperfusion from 6853 to 3796/mm3 (p less than 0.05), and lung histology after 2 hours showed proteinaceous exudates and leukosequestration of 62 PMN/10 high-powered fields (HPF), higher than the 22 PMN/10 HPF (p less than 0.05) in sham animals (n = 3). Recruitment of the pulmonary vasculature by left atrial balloon inflation (n = 3) resulted in a rise in MPAP to 20 mmHg. After 3 hours of balloon inflation, QL stabilized at 9.8 ml/15 minutes, and a pressure-independent L/P protein ratio of 0.3 was achieved. During reperfusion, QL increased further to 11.2 ml/15 minutes, the L/P ratio rose to 0.56 and the calculated osmotic reflection coefficient decreased from 0.70 to 0.44, documenting an increase in lung microvascular permeability. In contrast to these untreated ischemic controls, sheep (n = 7) rendered leukopenic with hydroxyurea or nitrogen mustard and having a total WBC count of 760/mm3 and PMN count of 150/mm3 did not manifest reperfusion-induced increases in MPAP, Pmv, QL, lymph protein clearance, or lung lymph. TxB2 level (p less than 0.05). Plasma TxB2 levels rose slightly at 30 minutes from 199 to 288 pg/ml (p less than 0.05). Lung histology was normal. These data indicate that WBC mediate the ischemia-induced increase in pulmo

Topics: Animals; Blood Pressure; Capillary Permeability; Female; Hindlimb; Ischemia; Leukocyte Count; Leukocytes; Lung; Lymph; Pulmonary Artery; Reperfusion Injury; Sheep; Thromboxane B2

The circulating prostaglandins have been implicated as mediators of microcirculatory derangements in skin and skin-muscle flaps. The study described here investigated the roles of thromboxane A2 and prostacyclin, measured as thromboxane B2 (TxB2) and prostaglandin 6-keto-F1a (PGF1a), in ischemic skin flaps, and the effects of thromboxane synthetase inhibition on flap blood flow and survival. A canine ventral island flap model was used to measure the appearance of TxB2 and PGF1a in the central arterial and venous plasma, and in the tissue and venous effluent of acutely raised flaps; with and without pretreatment with the specific thromboxane A2 synthetase inhibitor UK38485. Prostaglandin levels change significantly during flap elevation, and can be modified beneficially by thromboxane A2 synthetase inhibition, causing dramatic increases in flap blood flow and survival, as predicted by intravital dye penetration. The results presented in this article suggest that the manipulation of these compounds may provide a method of producing a pharmacological delay phenomenon and perhaps even allow effective intervention in the failing flap.

Topics: Animals; Dogs; Epoprostenol; Female; Imidazoles; Ischemia; Platelet Aggregation; Prostaglandins F; Skin; Surgical Flaps; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

The production of Platelet Activating Factor (PAF-acether) by glomeruli isolated from rats subjected to a 60 min renal ischemia has been studied. PAF-acether has been purified by Sep-Pak columns and measured by its ability to release serotonin from previously loaded rabbit platelets. Glomeruli from ischemic kidneys had higher amounts of PAF-acether activity than glomeruli from sham operated rats. These data suggest a role for PAF-acether in the renal functional alterations induced by renal ischemia.

Topics: Animals; In Vitro Techniques; Ischemia; Kidney Glomerulus; Kinetics; Platelet Activating Factor; Rats; Reference Values; Renal Circulation; Thromboxane B2

Lower torso ischemia and reperfusion has been shown to stimulate the generation of thromboxane (Tx)A2, leading to transient pulmonary hypertension and later to polymorphonuclear leukocyte accumulations in the lungs. This study investigated whether hind limb ischemia leads to increased pulmonary microvascular permeability. Anesthetized sheep (n = 6) previously prepared with a lung lymph fistula underwent 2 hr of tourniquet ischemia of both lower limbs. One minute following tourniquet release mean pulmonary arterial pressure (MPAP) rose from 14 +/- 1 to 36 +/- 4 mm Hg (p less than 0.05) and returned to baseline within 30 min. The pulmonary arterial wedge pressure of 4 +/- 1 mm Hg was unchanged. Plasma TxB2 levels rose from 211 +/- 21 to 304 +/- 52 pg/ml (p less than 0.05) 10 min after tourniquet release and were back to baseline at 30 min. Lymph flow (QL) rose from 4.3 +/- 0.6 ml/30 min to 8.3 +/- 1.8 ml/30 min (p less than 0.05); the lymph/plasma (L/P) protein ratio rose slightly but not significantly. In three sheep, inflation of a left atrial balloon increased left atrial pressure from 3 to 16 mm Hg. MPAP rose from 14 to 24 mm Hg. There was an increase in QL from 3.6 to 17 ml/30 min; the L/P protein ratio declined from 0.63 to 0.41. These results indicate that reperfusion following 2 hr of bilateral hind limb ischemia results in increased pulmonary microvascular permeability.

Topics: Animals; Capillary Permeability; Hypertension, Pulmonary; Ischemia; Leg; Lung; Neutrophils; Regional Blood Flow; Sheep; Thromboxane B2

Topics: Acute Kidney Injury; Animals; Cyclosporins; Dinoprostone; Dogs; Glomerular Filtration Rate; Ischemia; Kidney; Phosphates; Prostaglandins E; Prostaglandins F; Regional Blood Flow; Thromboxane B2; Vascular Resistance

Pretreatment with the thromboxane synthase inhibitor OKY-046 but not the cyclo-oxygenase inhibitor ibuprofen protects against ischemia-induced acute tubular necrosis. However, ibuprofen together with the vasodilating agent prostaglandin E1 is protective. This suggests that a high prostaglandin to thromboxane ratio is the major factor operative in preventing tubular necrosis, the subject of this study. Rats that had unilateral nephrectomy (n = 60) with the exception of rats that had sham operations (n = 8) underwent 45 minutes of left renal pedicle clamping. Thirty minutes before the operation, the rats received either a saline solution or a thromboxane synthase inhibitor that was given intravenously. The inhibitors OKY-046 (2 milligrams per kilogram, n = 10), UK38485 (1 milligram per kilogram, n = 9) and U63357A (10 milligrams per kilogram, n = 10) were given as a single bolus while the inhibitor CGS13080 (0.1 milligram per kilogram, n = 9, and 1.0 milligram per kilogram, n = 7) was given by constant infusion and continued for 60 minutes after reperfusion. With saline solution therapy, five minutes after reperfusion, thromboxane B2 increased from 154 to 2,537 picograms per milliliter (p less than 0.00001) and 6-keto-prostaglandin F1 alpha increased from 51 to 266 picograms per milliliter (p less than 0.004). At 24 hours, the creatinine level increased from 0.5 to 2.8 milligrams per deciliter (p less than 0.00001). Only OKY-046 yielded a creatinine level at 24 hours of 1.2 milligrams per deciliter, a value lower than that for those in the saline solution control group (p less than 0.002). Furthermore, OKY-046 led to the highest prostaglandin to thromboxane ratio (p less than 0.035). The five other ratios which occurred after drug therapy were inversely related to the decrease in the creatinine value (r = -0.93, p less than 0.02). Histologically, OKY-046 was the only thromboxane synthase inhibitor to prevent acute tubular necrosis (p less than 0.05). Results show that a high prostaglandin to thromboxane ratio protects against acute tubular necrosis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Benzofurans; Creatinine; Evaluation Studies as Topic; Ibuprofen; Imidazoles; Ischemia; Kidney; Kidney Tubular Necrosis, Acute; Male; Methacrylates; Pyridines; Rats; Thromboxane B2; Thromboxane-A Synthase

Ischemia stimulates thromboxane (Tx) synthesis. This study tests the hypothesis that the cardiopulmonary dysfunction that may follow aortic declamping is related to Tx. Anesthetized dogs (N = 15) were subjected to 4 hours of infrarenal aortic cross-clamping. In untreated control animals (N = 7), plasma levels of TxB2 rose from 654 +/- 74 pg/mL to 1238 +/- 585 pg/mL at 5 min (p less than 0.05), and to 3174 +/- 912 pg/mL 3 hours after declamping (p less than 0.05). Mean pulmonary artery pressure (MPAP) rose 5 min after declamping from 13 +/- 2 mmHg to 21 +/- 2 mmHg (p less than 0.05). Cardiac Index (CI) declined during ischemia from 181 +/- 30 mL/kg.min to 128 +/- 16 mL/min.kg (p less than 0.05), and to 80 +/- 8 mL/min.kg after 4 hours of reperfusion (p less than 0.05). Platelet counts declined but platelets labeled with In 111 did not accumulate in the lungs, whereas quantitative counts of polymorphonuclear leukocytes (PMN) in the lungs 4 hours after declamping yielded 213 +/- 33 PMN/25 high power fields (HPF) in dependent areas of the lung and 153 +/- 26 PMN/25 HPF in nondependent areas. The wet/dry weight ratio of the lungs was not elevated, although foci of proteinaceous exudate and PMNs in alveoli were noted. Another group of dogs (N = 8) were pretreated by random choice with the Tx synthase inhibitor OKY-046 2 mg/kg IV every 2 hours, which led to: lower TxB2 levels at baseline 95 +/- 35 pg/mL (p less than 0.05), 5 min after ischemia 140 +/- 93 pg/mL and after 3 hours of reperfusion 122 +/- 36 (p less than 0.05); lower MPAP, 16 +/- 2 mmHg (p less than 0.05); higher CI throughout (p less than 0.05); normal histology and reduced pulmonary PMN sequestration both in dependent 127 +/- 15 PMN/25 HPF and nondependent areas of the lungs 95 +/- 11 PMN/25 HPF (p less than 0.05). In animals undergoing sham ischemia (N = 3), levels of TxB2 and cardiopulmonary function remained unchanged from baseline. There were 150 PMN/25 HPF in dependent and 85 PMN/25 HPF in nondependent lung areas. The results indicate that ischemia-generated Tx mediates a rise in MPAP, a fall in CI, and PMN entrapment in the lungs.

Topics: Animals; Blood Pressure; Cardiac Output; Dogs; Female; Hypertension, Pulmonary; Ischemia; Leg; Leukocyte Count; Lung; Methacrylates; Neutrophils; Platelet Count; Respiratory Insufficiency; Thromboxane A2; Thromboxane B2; Time Factors

The effects of the inhibition of phospholipid degradation and superoxide radical generation on prostaglandin synthesis associated with myocardial ischemia and reperfusion were studied in the isolated, in-situ pig heart model subjected to 60 mins of regional ischemia and a further 60 mins of hypothermic potassium cardioplegic arrest, followed by 60 mins of reperfusion. Myocardial biopsies were taken from the ischemic and non-ischemic regions of the myocardium for measurement of phospholipids, and samples of the perfusate were drawn for estimation of the end-products of arachidonic acid metabolism, 6-keto-prostaglandin-F1 alpha and thromboxane B2. A significant amount of 6-keto-prostaglandin F1 alpha and thromboxane B2 appeared during reperfusion, corresponding with the loss of membrane phospholipids in control animals. Mepacrine, a phospholipase inhibitor, protected the depletion of membrane phospholipids and inhibited the products of arachidonate metabolism. Superoxide dismutase (SOD) and catalase, on the other hand, enhanced the formation of 6-keto-prostaglandin F1 alpha and thromboxane B2. The effects of both mepacrine and the free radical scavengers were pronounced during the reperfusion phase when the most significant depletion in membrane phospholipids occurred. These results suggest that the arachidonate cascade is activated during reperfusion of ischemic myocardium as a consequence of phospholipid breakdown, and this activation can be attenuated by inhibiting phospholipases or enhanced by scavenging oxygen-free radicals generated during reperfusion.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Arachidonic Acids; Catalase; Female; Heart; Ischemia; Male; Myocardium; Phospholipids; Prostaglandins; Quinacrine; Superoxide Dismutase; Swine; Thromboxane B2

Administration of dazoxiben (5 mg/kg, i.v.), which effectively suppressed plasma thromboxane concentrations, decreased the number of dogs that deteriorated into shock following a temporary (3-hr) splanchnic artery occlusion (SAO). Dazoxiben pretreatment also moderated the rise of plasma prostacyclin, but it augmented circulating prostaglandin E2 following the release of SAO. These alterations in arachidonic acid metabolism were accompanied by a moderation in the rise of plasma beta-glucuronidase activity, suggesting a moderation of tissue damage in the ischemic splanchnic region, and mitigation of the progressive hemodynamic deterioration caused by the SAO. The possible existence of causal relationships between the plasma eicosanoid concentrations, extent of damage in the ischemic splanchnic region, hemodynamic deterioration, and ultimate production of circulatory failure in dogs subjected to SAO are discussed.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Pressure; Cardiac Output; Dogs; Female; Glucuronidase; Heart Rate; Imidazoles; Indomethacin; Ischemia; Kinetics; Male; Shock; Splanchnic Circulation; Thromboxane B2; Thromboxane-A Synthase; Vascular Resistance

Reperfusion after limb ischemia results in muscle edema as well as excess secretion of thromboxane A2 (TxA2), an agent associated with permeability increase in other settings. This study tests whether TxA2 moderates the permeability following limb ischemia. A tourniquet inflated to 300 mmHg was applied for 2 hours around the hind limb of four groups of dogs. In untreated animals (N = 25), 2 hours following tourniquet release, plasma TxB2 values rose from 320 pg/ml to 2416 pg/ml (p less than 0.001), and popliteal lymph values rose from 378 pg/ml to 1046 pg/ml (p less than 0.001). Platelet TxB2 was unaltered and plasma 6-keto-PGF1 alpha levels did not vary. Following ischemia, lymph flow (QL) increased from 0.07 to 0.37 ml/h (p less than 0.05), while the lymph/plasma (L/P) protein ratio was unchanged at 0.41. These measurements indicate increased permeability since increase in hydrostatic pressure in a second group by tourniquet inflation to 50 mmHg (N = 7) led to a rise in QL from 0.07 to 0.22 ml/h, but a fall in the L/P ratio to 0.32, a value lower than the ischemic group (p less than 0.05). Pretreatment with the imidazole derivative ketoconazole (N = 11) reduced platelet Tx synthesis from 42 ng to 2 ng/10(9) platelets, but lymph TxB2 levels rose to 1703 pg/ml after ischemia, indicating an extravascular or vessel wall site of synthesis not inhibited by ketoconazole. Pretreatment with a lower molecular weight imidazole derivative OKY 046 (N = 9) inhibited all Tx synthesis after ischemia. Prior to tourniquet inflation, both OKY 046 and ketoconazole lowered plasma TxB2 levels as well as the L/P ratio (p less than 0.05). After ischemia, OKY 046, but not ketoconazole, maintained the L/P ratio at 0.33, a value below that of untreated animals (p less than 0.05). These results indicate that nonplatelet-derived TxA2 modulates both baseline and ischemia-induced increases in microvascular permeability in the dog hind limb.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Capillary Permeability; Dogs; Extremities; Ischemia; Ketoconazole; Thromboxane A2; Thromboxane B2

Since prostacyclin (PGI2) is known to regulate renal cortical blood flow and since ischemia stimulates thromboxane (Tx) A2 synthesis, the role of these prostanoids in moderating the response to renal ischemia was studied in the rat. At baseline, plasma TxB2 concentration in untreated animals (n = 13) was 357 pg/ml. The left renal pedicle was clamped for 45 minutes after a right nephrectomy (n = 16), which led after 5 minutes of reperfusion to a rise in TxB2 to 2825 pg/ml (p less than 0.001), but there was no change in 6-keto-PGF1 alpha. After 24 hours creatinine levels rose from 0.4 to 3.0 mg/dl (p less than 0.001), and left renal weight rose from 94% to 117% (p less than 0.001) relative to the weight of the right kidney. In nephrectomized but nonischemic sham control rats (n = 7), creatinine level was 0.9 mg/dl and kidney weight 91% after 24 hours. Pretreatment with OKY 046 (n = 13) (2 mg/kg administered intravenously) blocked ischemia-induced TxB2 synthesis, while 6-keto-PGF1 alpha levels rose from 96 to 302 pg/ml (p less than 0.001). There was no increase in creatinine levels or kidney weight relative to the sham group. Pretreatment with ibuprofen (n = 10) (12 mg/kg) or OKY 046 and ibuprofen (n = 9) inhibited TxB2 and 6-keto-PGF1 alpha synthesis, but creatinine levels and renal weight rose (p less than 0.001). Renal histology in OKY 046-pretreated animals was equal to that in nephrectomized controls, while all other ischemic groups showed tubular necrosis. Results indicate that a high PGI2/TxA2 ratio protects against renal ischemia.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Kidney Injury; Animals; Epoprostenol; Ibuprofen; Ischemia; Male; Methacrylates; Premedication; Rats; Renal Circulation; Thromboxane A2; Thromboxane B2; Thromboxanes

Excision of a kidney with three distinct zones of perfusion was required in a patient with renovascular hypertension. One third of the kidney was normal, one third was ischemic from a stenotic artery, and one third was severely ischemic from a completely occluded artery. This provided a unique opportunity to study renal prostaglandin production in hypoperfused and control tissue by radioimmunoassays of incubated tissue slices. The thromboxane-prostacyclin synthesis ratio for the outer cortex increased from 2.2 in control tissue to 5.8 in moderately ischemic tissue and 11.3 in severely ischemic tissue; for the inner cortex, 2.1 to 6.3 and 8.8; and for the medulla, 0.4 to 1.2 and 3.0, respectively . Similar ratios were noted for thromboxane-prostaglandin E2. This correlates, for the first time in man, absolute and relative increases in renal thromboxane synthesis with renovascular hypertension.

Topics: Humans; Hypertension, Renovascular; In Vitro Techniques; Ischemia; Kidney; Male; Middle Aged; Nephrectomy; Prostaglandins; Renal Artery; Thromboxane A2; Thromboxane B2; Thromboxanes

Thromboxane A2 is thought to be an important mediator of cardiopulmonary dysfunction, hence stimuli that effect synthesis of this prostanoid are of major interest. In this study, the thesis that ischemia of the limb is a significant stimulus to thromboxane A2 synthesis and the generation of a circulating negative inotrope is tested. Twelve healthy volunteers, taking no medications and ranging in age from 21 to 29 years, underwent inflation of an arm cuff to either 70 or 220 millimeters of mercury for ten minutes. Immediately after deflation of the cuff from 220 millimeters of mercury, the stable degradation product of thromboxane A2, thromboxane B2, rose from a base line plasma level of 34 +/- 6 picograms per milliliter (mean +/- SEM) to 70 +/- 18 picograms per milliliter. In contrast, deflation from a cuff pressure of 70 millimeters of mercury resulted in a lower thromboxane B2 level of 26 +/- 9 picograms per milliliter (p less than 0.05). Plasma obtained before and after inflation of the cuff to 220 millimeters of mercury was used to bathe a rat papillary muscle. Developed tension fell from a base line of 2.80 +/- 0.19 to 2.44 +/- 0.17 grams (p less than 0.01). There was no significant change in developed tension induced by plasma harvested after the cuff was inflated to 70 millimeters of mercury. The base line plasma level of 6-keto-prostaglandin F1 alpha, the hydrolysis product of prostacyclin, was 46 picograms per milliliter; the plasma serotonin, 51 nanograms per milliliter; the platelet serotonin, 1.02 micrograms per 10(9) platelets; platelet count, 220,000 per cubic millimeter, and white blood count, 6,094 per cubic millimeter. These values did not change significantly with cuff inflation to either 220 or 70 millimeters of mercury. The results show that ischemia of the limb leads to thromboxane A2 production. Possible adverse cardiac effects related to this event are suggested by the bioassay demonstrating that circulating plasma with high levels of thromboxane B2 is associated with the depression of tension of an isolated rat papillary muscle.

Topics: Adult; Arm; Humans; Ischemia; Myocardial Contraction; Thromboxane A2; Thromboxane B2; Thromboxanes

The role played by coagulation and platelet activation in the pathogenesis of retinal vein occlusions (RVO) has been evaluated by measuring beta-thromboglobulin (B-TG), circulating platelet aggregates (CPA), thromboxane B2 (TxB2) and fibrinopeptide A (FPA) in 25 patients less than 40 years old, investigated after the acute phase of RVO. FPA nd B-TG were significantly higher than in healthy subjects; CPA and TxB2 were not different. These abnormalities, found in patients free from apparent generalized vascular disease, suggest that a thrombophilic state characterized by coagulation and platelet activation is present in a high proportion of young patients with RVO.

Topics: Adolescent; Adult; beta-Thromboglobulin; Blood Coagulation; Blood Platelets; Female; Fibrinopeptide A; Humans; Ischemia; Male; Platelet Aggregation; Retina; Retinal Diseases; Retinal Vein; Thromboxane B2

To investigate the pathophysiology of ischemic heart disease (IHD), tourniquet ischemia on the upper limb was one and change in platelet aggregation, plasma 6-keto-PGF1 alpha concentrations and plasma thromboxane B2 (TXB2) concentrations were studied. At rest, platelet aggregability and plasma TXB2 concentrations were significantly increased in IHD patients compared with those in normal subjects (p less than 0.001 and p less than 0.001, respectively). In normal subjects, platelet aggregability, plasma 6-keto-PGF1 alpha concentrations and plasma TXB2 concentrations rose significantly during ischemia (p less than 0.05, p less than 0.02 and p less than 0.05, respectively). In addition, plasma 6-keto-PGF1 alpha concentrations were significantly lower in IHD patients than in normal subjects during ischemia (p less than 0.005), though there was no significant change in the level of either group at rest. These results suggest that increase in prostacyclin synthesis in normal subjects during tourniquet ischemia may be a defense mechanism to maintain the balance between prostacyclin and thromboxane A2 (TXA2) and to prevent platelet aggregation induced by the procedure. Increase in platelet aggregation and TXA2 generation in IHD patients at rest indicates a close correlation between IHD and platelet reactivity. Tourniquet ischemia induced a significant increase in prostacyclin generation in normal subjects but not in IHD patients, which suggests the production of prostacyclin was impaired in IHD patients during ischemia. A marked different was obvious in prostacyclin and TXA2 generation between IHD patients and normal subjects, and this difference may play an important role in the pathogenesis of IHD.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Arm; Blood Circulation; Coronary Disease; Female; Humans; Ischemia; Male; Middle Aged; Platelet Aggregation; Thromboxane B2; Thromboxanes; Tourniquets

Plasma beta-thromboglobulin (beta-TG), a marker of in-vivo platelet release reaction, was measured in 27 meniscectomy patients, 10 patients who underwent total knee replacements (TKR) (both procedures performed under tourniquet ischaemia), and 10 herniorrhaphy patients. In 22 meniscectomy and 7 TKR patients plasma-thromboxane-B2 (TxB2), a stable end-product of thromboxane-synthetase activity, was also determined. The mean plasma beta-TG and TxB2 had risen significantly within 5 min of release of the tourniquet, indicating increased in-vivo platelet release reaction and prostaglandin synthesis in these patients. In the herniorrhaphy patients beta-TG and TxB2 did not alter significantly postoperatively. In 6 pigs (weighing 20-30 kg) who underwent meniscectomy under tourniquet ischaemia plasma TxB2 rose significantly 15-30 min after release of the tourniquet, and prostacyclin release was significantly lower from veins exposed to ischaemia than from control veins. Large de-endothelialised areas were seen on scanning electron-micrographic sections of affected veins, and these areas were covered with a monolayer of platelets and platelet clumps. These changes associated with tourniquet ischaemia may explain the high incidence of venous thrombosis seen in patients undergoing meniscectomy and TKR.

Topics: Adult; Animals; beta-Thromboglobulin; Blood Platelets; Epoprostenol; Female; Humans; Ischemia; Knee; Male; Menisci, Tibial; Middle Aged; Prostaglandins; Swine; Thromboxane B2; Thromboxanes; Tourniquets