thromboxane-b2 and Raynaud-Disease

Raynaud's phenomenon has been suggested as a predisposing factor for pulmonary vasospasm which may lead to pulmonary hypertension, but the occurrence of cold stimulus-induced pulmonary vasospasm has been inconsistent. Such inconsistent pulmonary vascular responses may be caused by differences in the production of endogenous vasodilators and vasoconstrictors among patients. Fourteen patients with Raynaud's phenomenon associated with mixed connective tissue disease (n=10) or systemic sclerosis (n=4) participated in the study. Right heart catheterization was performed before and after a cold pressor test, immersing a hand in cold water (15 degrees C) for 5 min. Plasma levels of 6-keto prostaglandin (PG)F1alpha, thromboxane (TX)B2 and endothelin (ET)-1 in the mixed venous blood were measured. Mean pulmonary artery pressure increased after the cold pressor test in five of 14 patients, and the patients were divided into those with pulmonary vasospasm (responders) and those without vasospasm (nonresponders). After the cold pressor test, levels of 6-keto PGF1alpha increased significantly in nonresponders (p<0.01) and decreased significantly in responders (p<0.05). The ratios of 6-keto PGF1alpha to TXB2 significantly increased in nonresponders (p<0.01) but not in responders and the difference between responders and nonresponders after the cold pressor test was also statistically significant (p<0.05). No significant change in plasma ET-1 levels occurred in either responders or nonresponders. The results suggest that an impaired production of prostaglandin I2 and an imbalance between prostaglandin I2 and thromboxane A2 are associated with the occurrence of pulmonary vasospasm induced by Raynaud's phenomenon.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Cold Temperature; Endothelin-1; Female; Hemodynamics; Humans; Male; Middle Aged; Pulmonary Artery; Pulmonary Veins; Raynaud Disease; Respiratory Function Tests; Spasm; Thromboxane B2; Vascular Diseases

To determine whether measurement of different markers of endothelial damage, activation of coagulation, and platelet activation might differentiate between patients with primary Raynaud's phenomenon (PRP), limited cutaneous and diffuse systemic sclerosis (lcSSc and dSSc), and healthy control subjects.. Under carefully controlled conditions, fasting blood was drawn from 19 healthy control subjects, 10 patients with PRP, 17 with lcSSc and nine with dSSc for measurement of the following: von Willebrand factor (VWF) and soluble thrombomodulin as markers of endothelial damage/activation, thromboxane (as thromboxane B2) and beta-thromboglobulin as markers of platelet activation, and tissue plasminogen activator antigen, tissue plasminogen activator activity and plasminogen activator inhibitor-1 (PAI-1) as markers of fibrinolysis.. VWF was increased significantly in patients with SSc, and there was also a linear trend for thromboxane and tissue plasminogen activator antigen (in addition to VWF) to differentiate between different subgroups of patients with Raynaud's phenomenon. Patients with dSSc had the highest values. A combined index of VWF and thromboxane showed a highly significant trend across the four groups studied.. VWF, and to a lesser extent thromboxane and tissue plasminogen activator antigen, are associated with disease severity in patients with Raynaud's phenomenon. Prospective studies are now required to establish if these parameters can be used as markers of disease progression.

Topics: Adult; Antigens; beta-Thromboglobulin; Biomarkers; Discriminant Analysis; Female; Fibrinolysis; Humans; Male; Middle Aged; Plasminogen Activator Inhibitor 1; Platelet Activation; Raynaud Disease; Scleroderma, Systemic; Thrombomodulin; Thromboxane B2; Tissue Plasminogen Activator; von Willebrand Factor

As chronic exposure to hand-held vibrating tools may cause endothelial injury, a subsequent sustained platelet activation with the increased release of vasoconstricting thromboxane A2 (TxA2) could be of pathophysiological importance in vibration-induced Raynaud's phenomenon. Therefore, the aim of this study was to elucidate whether or not hand-arm vibration syndrome is accompanied by increased endogenous TxA2 biosynthesis. The study involved 64 men, aged 23-61 years, stratified according to the exposure to vibrating tools, the presence of Raynaud's phenomenon, and smoking habit. Forty of them were car mechanics and 24 were age-matched healthy volunteers who served as controls. The assessment of platelet TxA2 formation in vivo was performed by quantification of the urinary excretion of its major metabolite, 2,3-dinorthromboxane B2 (2,3-dinor-TxB2), employing gas chromatography-mass spectrometry. The average urinary excretion rate of 2,3-dinor-TxB2 in patients with Raynaud's phenomenon was 296 +/- 42 pg/mg creatinine and did not differ significantly from the corresponding values in controls (328 +/- 62 pg/mg creatinine) or individuals exposed to vibrating tools, but without any signs of vasospastic disease (232 +/- 29 pg/mg creatinine). The only statistically significant difference was found between smokers and non-smokers (P < 0.001), a finding confirming the existence of chronic platelet dysfunction in cigarette smokers. The present data indicate that chronic exposure to vibrating tools, with or without Raynaud's phenomenon, is not associated with an enhanced platelet function as monitored by the urinary excretion of 2,3-dinor-TxB2. Hence, a possible vibration-induced vascular injury does not seem to provide a stimulus sufficient to induce a persistent platelet activation.

Topics: Adult; Blood Platelets; Chromatography, Gas; Chromatography, Liquid; Creatinine; Humans; Male; Mass Spectrometry; Middle Aged; Raynaud Disease; Syndrome; Thromboxane A2; Thromboxane B2; Vasoconstriction; Vibration

As abnormal eicosanoid (prostaglandin) metabolism has been suggested as a factor in the aetiology of vasospastic diseases we have measured levels of stable eicosanoid metabolites using a radioimmunoassay in 30 normal subjects and 31 patients with Raynaud's phenomenon. There were 13 patients with primary Raynaud's, ten with Raynaud's secondary to scleroderma and eight men with vibration white finger (VWF) disease. We have also measured platelet aggregation to adenosine diphosphate (ADP), collagen and adrenaline in 19 normal subjects, 22 patients with primary Raynaud's, 12 with Raynaud's secondary to scleroderma and 14 men with VWF. When compared with our normal subjects, patients with VWF have an elevated thromboxane B2 level, with a normal 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) level. Their platelets are less sensitive to ADP and collagen. Patients with primary and secondary Raynaud's have elevated thromboxane B2 levels but this is much more marked in the secondary group. Patients with primary Raynaud's have a normal 6-keto-PGF1 alpha level but in patients with secondary Raynaud's the 6-keto-PGF1 alpha level is markedly raised. The platelets from both groups are more sensitive to ADP and collagen and this is more marked in the secondary group. Whether these phenomena are a cause or an effect of vasospasm remains unknown.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Aged; Female; Humans; Male; Middle Aged; Platelet Aggregation; Raynaud Disease; Scleroderma, Systemic; Thromboxane B2; Vibration

Prostaglandin metabolism and the clinical effect of epoprostenol (prostacyclin, PGI2) infusions were studied in thirteen patients with Raynaud's disease. Epoprostenol was infused at 5 ng/kg/min for six hours daily for two consecutive five day periods, separated by a two day interval. No beneficial effects either during or after infusion could be detected in terms of frequency of severity of attacks or on skin temperature measurement. Raynaud's patients had significantly lower serum thromboxane B2 levels than normal controls though plasma levels of thromboxane B2, 6-oxo-PGF1 and the bicyclic metabolite of PGE2 did not differ between the two groups. Platelets from Raynaud's patients had a significantly lower conversion rate of arachidonic acid into thromboxane B2 and HHT and a significantly higher rate of HETE production than platelets from controls.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Arachidonic Acid; Arachidonic Acids; Blood Platelets; Dinoprostone; Epoprostenol; Female; Humans; Infusions, Intravenous; Male; Middle Aged; Raynaud Disease; Skin Temperature; Thromboxane B2

Thromboxane A2, the predominant cyclo-oxygenase product of arachidonic acid in platelets, is a potent vasoconstrictor and platelet agonist. Analysis of urinary metabolites by gas chromatography and mass spectrometry is a specific non-invasive method of measuring the biosynthesis of thromboxane that avoids the problem of platelet activation ex vivo. Excretion of the major urinary thromboxane metabolite, 2,3-dinor-thromboxane B2, was significantly increased (p less than 0.001) in 10 patients (nine women) with systemic sclerosis complicated by Raynaud's phenomenon compared with healthy controls (486 (SD 88) v 162 (38) ng/g creatinine) and increased further in the patients (to 1007 (212) ng/g creatinine) during application of a cold stimulus sufficient to induce digital vasoconstriction. Consistent with an increase in platelet-vascular interactions in vivo, excretion of a prostacyclin metabolite was also significantly increased (p less than 0.005) in the patients with systemic sclerosis (248 (39) v 112 (10) ng/g creatinine) and tended to increase further on cooling. Biosynthesis of thromboxane is increased in patients with systemic sclerosis and may exacerbate digital vasospasm that such patients develop when cold. This observation and the concomitant increase in the formation of prostacyclin provide a rationale for evaluating compounds that prevent the synthesis of thromboxane A2 or inhibit its action while preserving the potential homoeostatic role of prostacyclin.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Cold Temperature; Female; Humans; Male; Middle Aged; Raynaud Disease; Scleroderma, Systemic; Thromboxane A2; Thromboxane B2

Platelet function was studied in 11 patients with Raynaud's syndrome and 11 healthy controls. Platelets obtained from patients with Raynaud's syndrome were significantly more responsive to adrenaline, produced more thromboxane A2, and were resistant to prostaglandin inhibitors (prostacyclin and prostaglandin E1) of platelet aggregation. Platelets from control subjects and patients with Raynaud's syndrome were more resistant to prostaglandin inhibitors when reactions were carried out at 27 degrees C rather than at 37 degrees C. Patients with Raynaud's syndrome also had significantly increased plasma concentrations of beta-thromboglobulin, fibrinogen, and circulating platelet aggregates. In an attempt to elicit local platelet responses, the forearms of control subjects and patients with Raynaud's syndrome were cooled in water tanks and platelet function tests performed before and after cooling. No significant difference in the results was observed. The potential role of platelets in the pathogenesis of Raynaud's syndrome is discussed.

Topics: Adult; Alprostadil; beta-Thromboglobulin; Blood Platelets; Cold Temperature; Epoprostenol; Female; Fibrinogen; Humans; Male; Middle Aged; Platelet Aggregation; Platelet Factor 4; Platelet Function Tests; Prostaglandins E; Raynaud Disease; Thromboxane B2

Dazoxiben, a specific thromboxane synthetase inhibitor, was evaluated in 21 patients with Raynaud's phenomenon in a double-blind, placebo-controlled crossover experiment. Total fingertip blood flows were measured by plethysmography and capillary blood flows were measured by 133Xe disappearance rate. Subjects were studied in both a warm (28 degrees) and a cold (20 degrees) room. Arteriovenous (AV) shunt flow was estimated by subtraction of capillary flow from total flow. Ex vivo production of thromboxane B2 (TXB2) and 6-keto PGF1 alpha was determined by specific radioimmunoassay in serum from venous blood incubated for 1 hr (37 degrees). Plasma concentrations of TXB2 and 6-keto PGF1 alpha were also monitored. Dazoxiben (100 mg 4 times a day for 14 days) inhibited ex vivo TXB2 production (from 463.1 +/- 69.9 to 101.8 +/- 13.4 ng/ml/hr; (means +/- SE], enhanced ex vivo 6-keto PGF1 alpha production (from 1.38 +/- 0.05 to 3.76 +/- 0.18 ng/ml/hr), reduced plasma TXB2 concentration (from 88.1 +/- 13.9 to 38.8 +/- 5.9 pg/ml). There were no changes in plasma concentration of 6-keto PGF1 alpha. Dazoxiben did not improve total digital blood flow, capillary flow, AV shunt flow, or forearm blood flow at 28 degrees or 20 degrees. There was no subjective improvement in frequency or severity of Raynaud's attacks (assessed by patient diaries). It is concluded that dazoxiben is a potent and specific thromboxane synthetase inhibitor capable of altering arachidonic acid metabolism, but is of little or no benefit in the treatment of Raynaud's phenomenon.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Arachidonic Acid; Arachidonic Acids; Double-Blind Method; Drug Evaluation; Female; Forearm; Humans; Imidazoles; Male; Middle Aged; Plethysmography; Radioimmunoassay; Raynaud Disease; Thromboxane B2

To examine the possibility that prostaglandin metabolism is pathophysiologically important in Raynaud's phenomenon, peripheral venous 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) and thromboxane B2 (TXB2) concentrations were measured in 45 patients with severe Raynaud's phenomenon. Patients with Raynaud's phenomenon had a significantly higher plasma concentration of 6-keto PGF1 alpha compared to controls (p less than .001), although their plasma TXB2 concentration was not statistically different from control patients. Subgroup analysis revealed that only patients with progressive systemic sclerosis (PSS) had an elevated plasma 6-keto PGF1 alpha concentration. To gauge the functional significance of the 6-keto PGF1 alpha elevations, seven patients with Raynaud's phenomenon were chronically administered indomethacin (50 mg P.O. b.i.d.); six of the seven patients noted no improvement in their Raynaud's phenomenon. Three of the patients developed pedal edema shortly after starting indomethacin. This study suggests that the increased plasma 6-keto PGF1 alpha concentration in Raynaud's phenomenon may be due to a compensatory release of prostacyclin and that the pathophysiologic defect does not involve the thromboxane mechanism.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Edema; Female; Humans; Indomethacin; Male; Middle Aged; Raynaud Disease; Thromboxane B2