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Improvement of vascular function by chronic administration of a cyclo‐oxygenase inhibitor in cholesterol‐fed rabbits
Author(s) -
Srisawat Supath,
Phivthongngam Laddawal,
Unchern Supeenun,
Chantharaksri Udom,
Govitrapong Piyarat,
Sanvarinda Yupin
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2003.03850.x
Subject(s) - aspirin , platelet , excretion , medicine , endocrinology , cholesterol , thromboxane , urinary system , thromboxane a2 , platelet activation , prostaglandin , prostacyclin , chemistry
Summary 1. Atherosclerotic cardio‐ and cerebrovascular disease is a leading cause of mortality in Western countries. Aspirin‐like drugs are widely used to prevent and treat these occlusive cardio‐ and cerebrovascular diseases. The beneficial effects of these drugs have been largely attributed to inhibition of platelet cyclo‐oxygenase activity and thromboxane (TX) A 2 production. We investigated the effect of an aspirin‐like drug, namely indomethacin, on endothelial function, plaque and platelet aggregation and the formation of vasoactive substances during the development of atherosclerosis in cholesterol‐fed rabbits. 2. Rabbits were fed 1% cholesterol ( n = 8), 1% cholesterol plus 25 mg/day indomethacin ( n = 8) or normal rabbit chow (control group; n = 8) for 12 weeks. Urinary excretion rates of 2,3‐dinor‐TXB 2 , 6‐keto‐prostaglandin (PG) F 1α , 8‐iso‐PGF 2α and nitrate were analysed at the beginning of dietary intervention and at 4 weekly intervals thereafter. At the end of the study period, platelet aggregation, aortic plaque formation and endothelium‐dependent and ‐independent vascular functions of isolated aortic rings ex vivo were assessed. 3. Compared with control, in the cholesterol‐fed group, urinary 2,3‐dinor‐TXB 2 , 6‐keto‐PGF 1α and 8‐iso‐PGF 2α excretion and platelet aggregation were significantly increased ( P < 0.05), but urinary excretion of nitrate was decreased ( P < 0.05). Treatment with indomethacin significantly reduced platelet aggregation, urinary 2,3‐dinor‐TXB 2 , 6‐keto‐PGF 1α and 8‐iso‐PGF 2α excretion ( P < 0.05 vs the cholesterol‐fed group) and attenuated the reduction in urinary nitrate excretion. 4. Cholesterol feeding progressively increased aortic intimal thickening and impaired endothelium‐dependent vasodilator function ( P < 0.05 vs control), whereas indomethacin partially prevented aortic plaque formation and restored endothelium‐dependent vasodilation ( P < 0.05 vs the cholesterol‐fed group). 5. The present study demonstrates that indomethacin reduces the progression of atherosclerotic lesions and improves endothelium‐mediated vascular responses ex vivo in cholesterol‐fed rabbits. The beneficial effects of indomethacin may be due to its ability to prevent the elevation of platelet aggregation, TXA 2 (measured as urinary 2,3‐dinor‐TXB 2 excretion) and 8‐iso‐PGF 2α formation and to retard the decrease in endogenous nitric oxide synthesis (assessed as urinary excretion of nitrate). Despite indomethacin treatment leading to the suppression of prostacyclin biosynthesis (assessed as urinary 6‐keto‐PGF 1α excretion), according to our data, indomethacin appears to preserve endothelial function.