fk-409 and Reperfusion-Injury

FK409 was discovered during a screening program for prostaglandin like compounds from microbial products by measuring inhibition of platelet aggregation and vasodilation. FK409, a semisynthetic compound derived from acidic nitrosation of microbial broth, was shown to be a potent vasodilator with a similar pharmacological profile to organic nitrates such as nitroglycerin (NTG). FK409 dilated the larger diameter coronary vascular vessels more potently than those with a smaller diameter in vitro, and was more potent than NTG in a dog angina pectoris model. Clinical development of FK409 for angina pectoris included a preliminary open efficacy study in about twenty patients with angina pectoris showing an improvement in 60-70 % of patients. Anemia proved a drug related adverse event. A new study was carried out on around 20 patients with ischemic heart disease, but in the longer term the anemia remained. It was concluded that FK409 had a comparable efficacy to organic nitrates, but an undesirable adverse effect, and development was terminated. Back-up compounds for FK409, explored improvement of the pharmacokinetic profile: an increase in duration of action and a reduction of the risk of anemia. The pharmacological action of FK409 was associated with increased cGMP levels in aortic smooth muscle; and release of NO was observed by physicochemical methods. Synthesis of chemically more stable derivatives of FK409 with slower NO release was aimed at longer pharmacokinetic profiles and a lower incidence of anemia. FR144220 and FR146881 were identified as chemically more stable compounds with a longer duration of pharmacological action.

Topics: Anemia; Angina Pectoris; Animals; Clinical Trials as Topic; Dogs; Humans; Imines; Nitric Oxide; Nitric Oxide Donors; Nitro Compounds; Organ Transplantation; Reperfusion Injury; Vasodilator Agents

We have demonstrated previously that preischemic treatment with FK409 [(+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide], a spontaneous nitric oxide (NO) donor, markedly improves ischemia/reperfusion-induced renal injury. However, there is conflicting information (renoprotective or cytotoxic) as to the contribution of NO to ischemic acute renal failure (ARF). In the present study, we investigated the effect of postischemic treatment with FK409 (1, 3, and 10 mg/kg i.v.) at 6 h after reperfusion on ischemic ARF, in comparison with the preischemic treatment effect. Ischemic ARF was induced by clamping of the left renal artery and vein for 45 min, followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in ARF rats markedly decreased at 24 h after reperfusion. Histopathological examination of the kidney of ARF rats revealed severe renal damage. In contrast to the renoprotective effect by preischemic treatment, postischemic treatment with FK409 aggravated the ischemia/reperfusion-induced renal dysfunction and histological damage. Immunohistochemical analysis of renal sections obtained from ARF rats revealed positive staining for nitrotyrosine, a biomarker of peroxynitrite formation, in injured tubular cells, and more intense staining was observed in renal tissues from the animals that received postischemic treatment with FK409. On the other hand, the formation of nitrotyrosine, neutrophil infiltration into renal tissues, and renal superoxide production, all of which were enhanced in ARF rats, were efficiently attenuated by the preischemic treatment with FK409. These results demonstrate that, although preischemic treatment with an NO donor is renoprotective, postischemic treatment with the same agent aggravates the ischemia/reperfusion-induced renal injury, probably through peroxynitrite overproduction.

Topics: Acute Kidney Injury; Animals; Blood Urea Nitrogen; Ischemia; Kidney; Male; Neutrophil Infiltration; Nitric Oxide Donors; Nitric Oxide Synthase Type II; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxides; Time Factors; Tyrosine

We have demonstrated that ischemic acute renal failure (ARF) is attenuated by pre-ischemic treatment with a spontaneous nitric oxide (NO) donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409). In the present study, we evaluated the effect of post-ischemic treatment with FK409 on ARF, compared with the pre-ischemic treatment effect. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. At 24 h after reperfusion, renal function in untreated ARF rats markedly decreased. In addition, increases in renal contents of endothelin-1 (ET-1), a deleterious mediator in the pathogenesis of ischemic ARF, were evident in untreated ARF rats at 24 h after reperfusion. Pre-ischemic treatment with FK409 (1 or 3 mg/kg, i.v.) at 5 min before ischemia attenuated ischemia/reperfusion-induced renal dysfunction and increased ET-1 contents after reperfusion. In contrast, post-ischemic treatment with FK409 (3 or 10 mg/kg, i.v.) at 6 h after reperfusion aggravated the renal injury, but did not affect the increased ET-1 content after reperfusion. These results suggest that pre-ischemic treatment with FK409 exerts renoprotective effects on ischemic ARF, probably through the suppression of renal ET-1 overproduction, whereas post-ischemic treatment with the NO donor worsens the ischemia/reperfusion-induced renal injury, through mechanisms unrelated to the ET-1 production after reperfusion.

Topics: Animals; Blood Urea Nitrogen; Creatinine; Endothelin-1; Kidney; Kidney Diseases; Kidney Failure, Chronic; Kidney Function Tests; Male; Nitric Oxide Donors; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury

To elucidate the role of nitric oxide (NO) in the pathogenesis of ischemic acute renal failure, we examined the effects of (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409) and N(G)-nitro-L-arginine methyl ester (L-NAME) as a NO donor and a non-selective NO synthase inhibitor on ischemia/reperfusion-induced renal injury and renal endothelin-1 content. Ischemic acute renal failure was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. At 24 h after reperfusion, renal function in untreated acute renal failure rats markedly decreased and histological examination revealed severe renal damage. In addition, increases in renal endothelin-1 contents were evident in the acute renal failure rats at 2, 6, and 24 h after reperfusion, respectively. Pretreatment with FK409 (1 or 3 mg/kg, i.v.) attenuated ischemia/reperfusion-induced renal dysfunction, histological damage, and endothelin-1 overproduction after reperfusion. In contrast, pretreatment with L-NAME (1 or 10 mg/kg, i.v.) aggravated renal injuries of acute renal failure rats at 24 h after reperfusion, and the effect is accompanied by further increases in the renal endothelin-1 content at 2 and 6 h, but not at 24 h, after reperfusion. These results suggest that suppressive effects of NO on the renal endothelin-1 overproduction induced by ischemia/reperfusion in an early phase are probably responsible for the protective effect of NO against ischemic acute renal failure.

Topics: Animals; Dose-Response Relationship, Drug; Endothelin-1; Kidney; Kidney Function Tests; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Nitro Compounds; Protective Agents; Rats; Rats, Sprague-Dawley; Renal Insufficiency; Reperfusion Injury; Time Factors

Organ ischemia-reperfusion injury is caused by two consecutive steps, microcirculatory disturbance and neutrophil-endothelial cell interactions, which are caused by inflammatory cytokines. We examined the hypothesis that combination therapy with a donor (FK409) of nitric oxide, one of the potent mediators with diverse roles as a vosodilator and a platelet inhibitor, together with the cytokine suppressor agent (FR167653) attenuates warm ischemic injury in canine small bowel. Small bowel ischemia was initiated by clamping the superior mesenteric artery and vein. Animals were divided into two groups: a control group (n = 5) subjected to 2-hour small bowel ischemia only, and a combination therapy group (FK/FR group, n = 5) that received FK409 (300 mcg/kg/h) plus FR167653 (1 mg/kg/h) intravenously before and after the ischemic event. We evaluated animal survival, small bowel tissue blood flow, and enzyme release from the small bowel. All controls died from severe acidosis within 2 days and all the FK/FR animals survived 7 days (P < .05). The FK/FR group recovered more than 70% of blood flow immediately after the revascularization, while the flow was less than 40% among the controls. Serum creatine phosphokinase values in the control group after reperfusion were significantly higher than those in the FK/FR group. In conclusion improvement of the microcirculation by FK409 and inhibition of cytokine release by FR167653 together attenuated warm ischemic small bowel injury.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Dogs; Intestine, Small; Ischemia; Models, Animal; Nitric Oxide Donors; Nitro Compounds; Pyrazoles; Pyridines; Reperfusion Injury

To elucidate the role of nitric oxide in the pathogenesis of ischemic acute renal failure, we investigated the effects of FK409, a spontaneous nitric oxide donor, and N(G)-nitro-L-arginine methyl ester, a non-selective nitric oxide synthase inhibitor, on ischemia/reperfusion-induced renal injury and endothelin-1 overproduction in post-ischemic kidneys. Ischemic acute renal failure was induced by occlusion of the left renal artery and vein for 45 minutes followed by reperfusion, 2 weeks after contralateral nephrectomy. At 24 hours after reperfusion, renal function in untreated acute renal failure rats markedly decreased and histological examination revealed severe renal damage of the kidney. Increases in renal endothelin-1 contents were evident in the acute renal failure rats at 2 and 24 hours after reperfusion, respectively. Pretreatment with FK409 (1 or 3 mg/kg, intravenously) dose-dependently ameliorated renal injuries and suppressed the elevation of endothelin-1 content induced by ischemia/reperfusion. In contrast, N(G)-nitro-L-arginine methyl ester (1 or 10 mg/kg, intravenously) pretreatment dose-dependently aggravated renal injuries of acute renal failure rats, and the effect is accompanied by further increase in the renal endothelin-1 contents. These results suggest that both exogenous and endogenous nitric oxide have protective effects against ischemia/reperfusion-induced renal dysfunction and tissue damage, probably through the suppression of endothelin-1 overproduction in post-ischemic kidneys.

Topics: Acute Kidney Injury; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Enzyme Inhibitors; Injections, Intravenous; Kidney; Kidney Function Tests; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Time Factors

In addition to localized tissue injury, intestinal ischaemia-reperfusion (I/R) leads to remote organ damage, in particular to the lungs. Given that nitric oxide (NO) can attenuate I/R-induced tissue injury in many situations, this study evaluated the effects of the NO donor, FK409, on leukocyte adhesion in the microcirculation of the intestinal villus and also assessed pulmonary tissue damage after intestinal I/R injury. PVG rats were subjected to 30 min intestinal ischaemia and a sub-group of animals received the NO donor FK409 (10 mg/kg; i.v.) both 30 min prior to ischaemia and 30 min post-reperfusion. The intestinal mucosal surface was visualized via an incision made in an exteriorized ileal segment and leukocyte adhesion in the villous microcirculation was determined by in vivo microscopy. Total and differential leukocyte counts from peripheral blood were evaluated. Lungs were removed at the end for histological assessment. Six out of ten untreated I/R animals failed to survive the 2 h reperfusion period, whereas all ten FK409-treated animals survived. I/R induced a significant increase in villous leukocyte adhesion of untreated I/R animals (p<0.001) and this was significantly decreased by FK409 treatment (p<0.001). The total leukocyte count was significantly decreased in untreated I/R animals (p<0.001) and this primarily resulted from a reduction in circulating neutrophil numbers. This effect was not observed in FK409-treated animals. Collapsed alveoli, thickened interstitial walls, and a dense neutrophilic infiltrate were apparent in the lungs of untreated I/R animals, whereas lung histology was normal in FK409-treated animals. In conclusion, FK409 prevented mortality, significantly reduced villous leukocyte adhesion, maintained circulating leukocyte numbers, and prevented pulmonary tissue injury following intestinal I/R. FK409 may therefore be of value in reducing both local and remote tissue damage and improving outcome in situations where intestinal I/R injury is obligatory, such as small bowel transplantation.

Topics: Animals; Blood Pressure; Cell Adhesion; Heart Rate; Intestine, Small; Ischemia; Leukocyte Count; Leukocytes; Lung; Male; Nitric Oxide Donors; Nitro Compounds; Rats; Rats, Inbred Strains; Reperfusion Injury; Survival Analysis; Vasodilator Agents

Nitric oxide (NO) appears to play an important role in tissue injury during reperfusion. FK409 is the first spontaneous NO donor that increases plasma guanosine 3',5'-cyclic monophosphate. We investigated the effects of the NO donor FK409 (FK) on ischemia-reperfusion injury in a canine warm ischemia model. Fourteen adult mongrel dogs were divided into two groups: the control group and the FK group, which received FK. The superior mesenteric artery and vein were both clamped for 2 h and then reperfused for 12 h. Arterial and intramucosal pH were well maintained in the FK group in comparison with the control group. Histologically, ischemia-reperfusion injury was significantly more severe in the control group than in the FK group. The serum NO levels were significantly higher in the FK group than in the control group during FK administration. FK409 has protective effects on ischemia-reperfusion injury of the small intestine due to NO release.

Topics: Animals; Blood Pressure; Dogs; Hydrogen-Ion Concentration; Intestinal Mucosa; Intestine, Small; Nitric Oxide; Nitric Oxide Donors; Nitro Compounds; Reperfusion Injury

Nitric oxide attenuates ischemia-reperfusion injury by maintaining organ circulation through its actions as a vasoregulator, an inhibitor of platelet aggregation, and an attenuator of leukocyte adhesion. Otherwise, the harmful effects of enhanced nitric oxide production induced by inducible nitric oxide synthase mediate ischemia-reperfusion injury. FK409 has been characterized as a spontaneous nitric oxide donor. The aim of this study was to evaluate the effects of FK409 on extended liver resection with ischemia using a canine model.. Adult mongrel dogs were subjected to 60 minutes of warm ischemia by partial inflow occlusion. After reperfusion the nonischemic lobes were resected and the remnant liver function was evaluated. The dogs were divided into two groups: the control group (n = 7) and the FK409 group (n = 6), which was given FK409 through the portal vein.. The hepatic tissue blood flow, serum liver enzymes levels, and serum endothelin-1 level after reperfusion were significantly better in the FK409 group than in the control group. Electron microscopy demonstrated that endothelial cells and Ito cells were well-preserved in the FK409 group. The 3-day survival rate was statistically better in the FK409 group (67%) than in the control group (14%).. FK409 appears to have protective effects during extended liver resection with ischemia.

Topics: Animals; Disease Models, Animal; Dogs; Hepatectomy; Liver; Liver Circulation; Nitric Oxide Donors; Nitro Compounds; Reperfusion Injury

The small intestine is extremely sensitive to ischemia-reperfusion (I/R) injury and a range of microcirculatory disturbances contribute to tissue damage. Nitric oxide (NO) seems to be involved in tissue protection after I/R injury. This study therefore assessed the effects of the NO donor, FK409, on intestinal I/R injury and changes induced in intestinal microcirculation.. PVG rats were subjected to 30-min intestinal ischemia with a subgroup of animals receiving FK409 (10 mg/kg i.v.) 30 min before ischemia and 30 min postreperfusion. Controls underwent sham surgery. The mucosal surface was visualized via an incision made in an exteriorized ileal segment and FITC-BSA or acridine orange was used to quantitate macromolecular leak (MML) and leukocyte adhesion, respectively. MML from, and numbers of adherent leukocytes within, individual villi were determined every 15 min for 2 hr after removal of the vessel clamp. Heart rate and mean blood pressure (mBP) were monitored throughout the experiment.. Eleven of 12 untreated animals subjected to intestinal I/R injury failed to survive the 2 hr reperfusion period, whereas all 12 FK409-treated animals survived. MML and leukocyte adhesion were increased in untreated animals (P<0.001), and blood flow stasis eventually ensued. Although FK409 decreased mBP (P<0.001), MML and leukocyte adhesion were significantly (P<0.001) reduced, and villus blood flow was maintained throughout the observation period.. FK409 prevented mortality after intestinal I/R, significantly reduced leukocyte adhesion, and maintained blood flow after intestinal ischemia and may therefore be of value in reducing tissue damage and improving outcome after small bowel transplantation.

Topics: Animals; Blood Pressure; Capillary Permeability; Cell Adhesion; Heart Rate; Intestinal Mucosa; Intestines; Ischemia; Leukocytes; Male; Microcirculation; Microvilli; Nitric Oxide Donors; Nitro Compounds; Rats; Rats, Inbred Strains; Regional Blood Flow; Reperfusion Injury; Survival Analysis

Nitric oxide (NO) seems to play an important role in tissue injury during reperfusion of the lung. FK409 is the first spontaneous NO donor that increases plasma guanosine 3':5'-cyclic monophosphate. It is reported that FK409 prevented myocardial infarction following occlusion and reperfusion in rat coronary arteries. In this study, we evaluated the effects of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia model of rats.. Animals were divided into 2 groups: the FK409 study group that was administered FK409 (0.4 mg/kg) before reperfusion and the control group, administered a saline vehicle only. Following a thoracotomy, the bronchus, pulmonary artery and vein were separately clamped for 1 hour. Arterial oxygen tension (PaO2), arterial oxygen saturation (SaO2), and endothelin-I (ET-I) were measured after 2 hours of reperfusion. Histologic and immunohistochemical studies were performed; polymorphonuclear neutrophils (PMNs) were counted after 2 hours of reperfusion.. PaO2, SaO2, ET-I after 2 hours of reperfusion and the 7-day survival rate were significantly (p < 0.05) better in the FK409 group than the control group. Histologic damage was reduced in the FK409 group compared with the control group. PMN infiltration was also significantly (p < 0.05) lower in the FK409 group than in the control group.. FK409 seems to protect against ischemia-reperfusion injury of the lung. This effect may be related to a homeostatic effect on pulmonary vascular beds and prevention of PMN sequestration.

Topics: Animals; Endothelin-1; Immunohistochemistry; Lung; Lung Transplantation; Male; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitro Compounds; Oxygen; Pulmonary Edema; Rats; Rats, Wistar; Reperfusion Injury

Nitric oxide (NO) is known to have beneficial effects in ischemia-reperfusion (I/R) injury through maintaining endothelial integrity, inhibiting leukocyte adhesion and platelet aggregation, and inducing vasodilation. The effect of FK409 (FK), a spontaneous NO donor, was investigated in a canine lung transplantation model.. Ten pairs of weight-matched dogs were used. Five pairs were assigned to the FK group, to which FK (5 microg/kg/min) was administered intravenously from 30 minutes prior to ischemia until the induction of ischemia in the donor, and from 15 minutes prior to reperfusion until 45 minutes after reperfusion in the recipient. The others were assigned to the control group. After 8-hour preservation in 4 degrees C Euro-Collins solution, orthotopic single-lung transplantation was performed. During a 5-minute clamping test of the right pulmonary artery, left pulmonary arterial pressure (L-PAP), left pulmonary vascular resistance (L-PVR), arterial oxygen pressure (PaO(2)), and alveolar-arterial oxygen pressure difference (A-aDO(2)) were measured. The lung specimens were harvested for histologic study, and polymorphonuclear neutrophils (PMNs) were counted. Pulmonary perfusion and ventilation scintigraphy (Tc-99m-MAA and Xe-133) were performed.. PAP, L-PVR, PaO(2), and A-aDO(2) revealed significantly (p < 0.05) better function in the FK group than in the control group. Histologically, edema was more mild, and PMN infiltration was significantly (p < 0.05) lower in the FK group than in the control group. Xe-133 and Tc-99m-MAA were widely distributed throughout the graft lung in the FK group. The 2-day survival rate was 100% in the FK group, which was significantly (p < 0.05) better than the rate (40%) in the control group.. FK appears to generate a protective effect on I/R injury in lung transplantation.

Topics: Animals; Cardiac Output; Dogs; Endothelin-1; Lung; Lung Transplantation; Nitric Oxide; Nitric Oxide Donors; Nitro Compounds; Oxygen; Pulmonary Circulation; Pulmonary Gas Exchange; Radiography; Reperfusion Injury

Topics: Animals; Endothelin-1; Lung; Macrophages, Alveolar; Male; Neutrophils; Nitro Compounds; Oxygen; Partial Pressure; Pulmonary Alveoli; Pulmonary Circulation; Rats; Rats, Wistar; Reperfusion Injury; Tidal Volume; Vasodilator Agents

Topics: Animals; Cardiac Output; Dogs; Endothelin-1; Hemodynamics; Lung; Neutrophils; Nitric Oxide Donors; Nitro Compounds; Oxygen; Partial Pressure; Pulmonary Artery; Pulmonary Circulation; Pulmonary Veins; Reperfusion Injury

The suppressed production of nitric oxide (NO), associated with endothelial dysfunction, is thought to be a cause of ischemia and reperfusion injury of the liver. But findings of the salutary effects of NO enhancement on such injury have been conflicting. In this study, we tested our hypothesis that NO enhancement would attenuate ischemic liver injury. For this purpose, an NO precursor, L-arginine, and a novel NO donor, FK409, were applied to a 2-hour total hepatic vascular exclusion model in dogs.. L-arginine was administered IV at a dose of 100 mg/kg twice (n = 5), while 300 mg/kg twice of FK409 was infused continuously into the portal vein (n = 5). The drugs were given to the animals for 30 and 60 minutes before and after ischemia, respectively. Non-treated animals were used as the control (n = 10). Two-week survival, systemic and hepatic hemodynamics indices, liver function tests, energy metabolism, and histopathology were analyzed.. Both treatments comparably augmented hepatic tissue blood flow, decreased liver enzyme release, and increased high-energy phosphate restoration during the reperfusion period, all of which contributed to rescuing all of the treated animals from the 2-hour total hepatic ischemia. In contrast, ischemia caused 70% mortality in the control group. Histologically, structural abnormality and neutrophil infiltration were markedly attenuated by the treatments. Systemic hypotension was observed in the animals treated with FK409, however.. Our data demonstrate that NO enhancement alleviates the liver injury caused by ischemia and reperfusion. The supplementation of L-arginine, rather than FK409, is considered more applicable to clinical use because of the absence of systemic adverse effects.

Topics: Adenine Nucleotides; Alanine Transaminase; Animals; Arginine; Aspartate Aminotransferases; Bile Acids and Salts; Dogs; Female; Hyaluronic Acid; L-Lactate Dehydrogenase; Liver; Nitric Oxide; Nitric Oxide Donors; Nitro Compounds; Regional Blood Flow; Reperfusion Injury

FK409 is the first spontaneous nitric oxide (NO) donor known to increase plasma cyclic guanosine 3',5'monophosphate levels. In this study, we evaluated the effect of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia canine model. Fourteen dogs were divided into two groups, and the FK409-treated group was given 5 micrograms/kg per min FK409. Warm ischemia was induced for 3 h. The arterial partial pressure of oxygen (PaO2), arterial oxygen saturation (SaO2), cardiac output (CO), left pulmonary vascular resistance (L-PVR), and endothelin-I (ET-I) were measured. A histologic study was performed, and polymorphonuclear neutrophils (PMNs) were also counted. The PaO2, SaO2, and L-PVR levels and PMNs after 30 min of reperfusion, ET-I after 2 h of reperfusion, and the 7-day survival rate were significantly (P < 0.05) better in the FK409-treated group than in the control group. The histologic damage was reduced in the FK409-treated group compared to the control group. FK409 appears to have a protective effect in ischemia-reperfusion injury of the lung.

Topics: Animals; Cardiac Output; Cyclic GMP; Dogs; Drug Evaluation, Preclinical; Endothelin-1; Ischemia; Lung; Nitric Oxide Donors; Nitro Compounds; Oxygen; Partial Pressure; Pulmonary Edema; Reperfusion Injury

ET receptor blocker (TAK-044) and NO donor (FK409) were used to improve the hepatic microcirculation following ischemia-reperfusion injury. In the first experiment (60 minutes of ischemia), 15 dogs were divided into three groups: group A (control), saline; group B, TAK 5 mg/kg; and group C, FK 0.4 mg/kg. In the second experiment (90 minutes of ischemia), 38 dogs were divided into six groups that underwent 90 minutes of hepatic ischemia followed by reperfusion: group I (control), saline only; group II, TAK 5 mg/kg and FK 3.2 mg/kg; group III, TAK 5 mg/kg and FK 0.4 mg/kg; group IV, TAK 5 mg/kg; group V, FK 0.4 mg/kg; and group VI, FK3.2 mg/kg. All drugs were administered through the portal vein. Following 60 minutes of ischemia, both FK and TAK produced significant improvement in hepatic microcirculation and enzymatic status when compared with the control group. After 90 minutes of ischemia, low doses of FK and TAK significantly improved hepatic microcirculation and reduced portal pressure following reperfusion in group III compared with group I. Leakage of hepatic enzymes was prevented and tissue injury score was significantly lower in group III. In group VI, early protection was obtained to some extent; however, blood pressure was reduced significantly following reperfusion compared with group I. In contrast, hepatocellular function deteriorated and the tissue injury score was higher in group II animals. TAK pretreatment with low doses of FK provided the best protection for the hepatic microcirculation in ischemia-reperfusion injury of the liver.

Topics: Animals; Blood Pressure; Creatine Kinase; Dogs; Endothelins; Female; Ischemia; Isoenzymes; Liver; Liver Circulation; Male; Microcirculation; Nitric Oxide; Nitro Compounds; Peptides, Cyclic; Reperfusion Injury

Nitric oxide (NO) seems to play an important role in modulating tissue injury during reperfusion of the liver. In this study, we have evaluated and compared the effects of FK409 (FK), a potent spontaneous NO releaser, and L-arginine in ischemia-reperfusion injury of the rat liver.. Male Sprague-Dawley rats underwent 90 min of hepatic ischemia followed by reperfusion. FK or L-arginine was used (intravenously) in two different doses for each drug (group I, 3.2 mg/kg FK; group II, 1.6 mg/kg FK; group IV, 100 mg/kg L-arginine; and group V, 300 mg/kg L-arginine). Saline was used in control animals (group III). Hepatic enzyme status, microcirculation, serum nitrite (NO2-) and nitrate (NO3-) and tissue injury score were evaluated at predetermined times.. Serum NO2-/NO3- was elevated immediately by FK treatment dose-dependently but not by L-arginine. However, L-arginine caused late (6-24 hr) elevation of the NO metabolites dose-dependently. The elevation of serum aspartate aminotransferase and alanine aminotransferase was suppressed and hepatic microcirculation was improved in the FK-treated groups dose-dependently. L-Arginine also improved the microcirculation, but hepatic enzymes at 24 hr of reperfusion were significantly higher in group V than in the control group. These findings were well reflected by the extent of tissue injury in respective groups.. FK treatment in the immediate reperfusion period improves hepatic microcirculation and confers a significant protective effect on hepatic ischemia-reperfusion injury in the rat.

Topics: Animals; Arginine; Liver; Male; Nitric Oxide; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Vasodilator Agents

The contribution of nitric oxide (NO) to ischemic acute renal failure (ARF) is controversial. In the present study, we investigated the effect of FK409 ((+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexanamide ), a spontaneous NO donor, on ischemic ARF in rats. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal functional parameters such as blood urea nitrogen, plasma creatinine, creatinine clearance, urine flow, urinary osmolality and fractional excretion of sodium were measured to test the effectiveness of the drug. Renal function in untreated ARF rats markedly decreased at 24 hr after reperfusion and thereafter tended to recover gradually. Intravenous bolus injection of FK409 at a dose of 1 mg/kg before the occlusion markedly attenuated the ischemic ARF-induced decreases in renal function, to the same extent as verapamil (1 mg/kg i.v.). The protective effect of FK409, at a dose of 3 mg/kg, was much more potent than that of the lower dose. Histopathological examination of the kidney of untreated ARF rats revealed severe renal damages, such as tubular necrosis, proteinaceous casts in tubuli and medullary congestion. These renal damages were significantly attenuated by treatment with FK409, at each dose given and this attenuation exceeded that seen with verapamil treatment. FK 409 administration led to a dose-dependent increase in NO metabolites concentration in renal venous blood immediately after the reperfusion. These findings suggest that NO has a crucial role in the pathogenesis of ischemic ARF. Spontaneous NO donors may be clinically effective in cases of ischemic ARF.

Topics: Acute Kidney Injury; Animals; Blood Urea Nitrogen; Calcium Channel Blockers; Creatinine; Kidney Medulla; Male; Nitric Oxide; Nitro Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Vasodilator Agents; Verapamil