Nitric Oxide And Pulmonary Hypertension In Rats Studied

Endogenous nitric oxide (NO),an endothelium-derived relaxing factor,may produce potent vasodilation and inhibit the mitogenesis and proliferation of vascular smooth muscle cells. Recent data suggest that chronic hypoxic pulmonary hypertension is associated with the decreased synthesis and release of NO.Short-term inhalation of low concentration NO can give rise to selective pulmonary vasodilation without toxicity. The aim of present study was to observe the effect of chronic hypoxia and of L-arginine on metabolism of endogenous NO in hypoxic rats and explore the effect and toxicity of long-term inhalation of NO on base of developing simple NO exposing system.1. Changes in endogenous NO in rats during chronic hypoxia and administration of L-arginineWistar rats were divided into 5 groups: (1) room-air control(C); (2) hypoxia for 1 week(H1w); (3) hypoxia for 2 weeks(H2w); (4) hypoxia for 3 weeks(H3w);5 hypoxia with L -arginine(HL). The hypoxic rats werekept in a hypobaric chamber (380mmHg) for 8hrs/d. Group HL were managed with L -arginine 500mg/kg once daily subcutaneously for 3 weeks. RY/LV+S,mPAP and plasma cGMP were measured.It was shown that mPAP and RV/LV+S increased markedly(P<0. 05,P<0. 001 vs Group C) in Group H1w and increased more in Group H2w...