EFFECT OF CAPTOPRIL ON PLATELET CYTOSOLIC [CA2+](I) AND PLASMA TXA(2)PGI(2) IN RENOVASCULAR HYPERTENSIVE RATS/

AIM: To study the effect of captopril (Cap) on platelet cytosolic free calcium concentration ([Ca2+](i)), platelet aggregation (PAg), and pl asma TXA(2)/PGI(2) ratio in the renovascular hypertensive rats. METHOD S: Blood pressure was measured once a week by tail-cuff microphonic ma nometer. Platelet [Ca2+](i) was measured by Fura 2-AM. Plasma angioten sin II (Ang), thromboxane A(2) (TXA(2)), and prostacycline (PGI(2)) we re measured by radioimmunoassay. RESULTS: Platelet [Ca2+](i) and PAg i ncreased (P < 0.01), while plasma Ang and TXA(2)/PGI(2) ratio elevated (P < 0.05) in the renovascular hypertensive rats; platelet [Ca2+](i) and plasma TXA(2)/PGI(2) ratio reduced markedly after ig Cap 100 mg.kg (-1).d(-1) compared with saline for 2 wk. CONCLUSION: The altered TXA( 2)/PGI(2) after Cap treatment contributed to the improvement of the pl atelet [Ca2+](i) and PAg.