ABSTRACT
OBJECTIVES: The aim of this study was to find out the effects of cyclo-oxygenase and thromboxane synthetase inhibitors on right atrial prostacyclin and thromboxane A2 levels. METHODS: The study consisted of a total of 50 patients subjected to coronary bypass surgery. These patients were divided into two groups, Group I and Group II each consisting of 25 patients. In Group I patients, the right atrial tissues were studied for effects of indomethacin and U63557A on the prostaglandin levels. In Group II patients, the right atrial tissues were studied for effects of Aspirin and U63557A on the prostaglandin levels. RESULTS: In Group I patients, the atrial tissues pretreated with indomethacin showed a fall in the levels of 6 keto PGF1 alpha from 153.5 +/- 28.4 pg/0.1 mg to 59.7 +/- 11.6 pg/0.1 mg and of TXB2 from 41.6 +/- 1.2 pg/0.1 mg to 17.2 +/- 3.2 pg/0.1 mg. In the atrial tissues of Group I treated with U63557A the levels of 6 keto PGF1 alpha fell to 145.4 +/- 26.8 pg/0.1 mg and the levels of TXB2 fell to 14.7 +/- 2.8 pg/0.1 mg. In Group II patients, the atrial tissues pretreated with aspirin, showed a fall in the levels of 6 keto PGF1 alpha from 142.1 +/- 2.8 pg/0.1 mg to 17.5 +/- 0.8 pg/0.1 mg. In the atrial tissues pretreated with U63557A, the levels of 6 keto PGF1 alpha fell to 131.2 +/- 2.9 pg/0.1 mg and the levels of TXB2 fell to 14.4 +/- 0.7 pg/0.1 mg. CONCLUSIONS: The study showed that human right atrial tissues are capable of producing TXA2 in addition to prostacyclin. Indomethacin and aspirin by inhibiting generation of cyclic endoperoxides inhibited synthesis of both prostacyclin and TXA2. In contrast a thromboxane synthethase inhibitor U63557A selectively inhibited TXA2 without significant effects on prostacyclin synthesis.
Subject(s)
Aspirin/pharmacology , Benzofurans/pharmacology , Coronary Artery Bypass , Coronary Disease/pathology , Culture Techniques , Cyclooxygenase Inhibitors/pharmacology , Enzyme Inhibitors/pharmacology , Heart Atria/pathology , Humans , Indomethacin/pharmacology , Prostaglandins/metabolism , Thromboxane A2/metabolism , Thromboxane-A Synthase/antagonists & inhibitorsABSTRACT
An extensive body of research conducted in the past 25 years has helped foster understanding of the mechanisms and pathogenesis of the acute coronary syndromes and occlusive disease. The role of platelet and the endothelium in the pathogenesis of atherosclerosis and subsequent ischemic events is well established. The filed of antiplatelet therapy is rapidly expanding with the availability of newer antiplatelet agents. However, at the present time, there is no convincing data available that other antiplatelet drugs are superior to aspirin. Aspirin remains the cornrstone of therapy for various ischemic disorders and the foundation on which other therapies are added, both in the short and long term
Subject(s)
Aspirin/pharmacology , Ticlopidine/pharmacology , Thromboxane-A Synthase/antagonists & inhibitors , Platelet Glycoprotein GPIIb-IIIa Complex/antagonists & inhibitors , Thrombosis/etiology , Platelet Aggregation , Myocardial IschemiaABSTRACT
The therapeutic effect of a thromboxane A2 (TXA2) synthetase inhibitor on asthma is still controversial. This study was aimed at clarifying its effect on asthmatic reactions in guinea pigs. Both ovalbumin (OVA)- and platelet activating factor (PAF)-induced dual phase airway spasm and hyperreactivity in guinea pigs were used as the asthma model. Our results demonstrated that aerosol administration of OKY-046 could inhibit both OVA- and PAF-induced late phase bronchoconstriction and airway hyperreactivity to methacholine in OVA sensitized guinea pigs. PAF administration could also induced dual phase bronchoconstriction in normal guinea pigs. Similarly, late phase airway spasm and airway hyperreactivity after PAF exposure was also blocked by OKY-046. In conclusion, aerosol administration of OKY-046 is a safe and effective way to modulate OVA- and PAF-induced asthmatic reactions. The protective effect of OKY-046 on OVA- and PAF-induced late phase bronchoconstriction and airway hyperreactivity indicates that TXA2 might play an important role in the late phase asthmatic reaction and airway hyperreactivity. The normalization of PAF-induced airway hyperreactivity by OKY-046 also indicates that PAF induced airway inflammation might be through the generation of TXA2.
Subject(s)
Animals , Asthma/chemically induced , Bronchial Hyperreactivity/chemically induced , Dose-Response Relationship, Drug , Guinea Pigs , Histamine Antagonists/therapeutic use , Male , Methacrylates/therapeutic use , Ovalbumin , Platelet Activating Factor , Thromboxane-A Synthase/antagonists & inhibitors , Time FactorsABSTRACT
OBJECTIVE: To explore the role of prostaglandins in protecting against chilli-induced early gastric vascular damage. METHODS: Early gastric vascular damage was induced in rats by oral administration of 8 mg/Kg chilli extract. The damage was assessed by estimating spectrophotometrically the amount of Evan's blue leaking into gastric tissue and luminal contents 10 min after exposure to chilli. Further groups of rats were pretreated with misoprostol (10, 25 or 50 micrograms/Kg) or dazmegrel (1, 5 or 25 mg) to evaluate their protective effects. RESULTS: Both misoprostol and dazmegrel were able to reduce gastric vascular damage induced by chilli in a dose-dependent fashion. CONCLUSION: Prostaglandins may play a role in protecting against chilli-induced early gastric vascular damage.