缺氧对右心室最大心肌血流量的影响

为了探讨缺氧对冠状血管贮备力的影响，我们观察了缺氧时大鼠血流动力学及右心室最大心肌血流量的变化。结果表明，急性缺氧引起ＰａＯ２、心输出量及氧运送量降低，但右心室心肌血流量增加，右心室最大与安静血流量比值降低。慢性缺氧时ＰａＯ２降低，血球比积和右心室重量指数增加，氧运送量和右心室血流量正常，但最大血流量降低，小动脉增厚、外膜胶元增加。以上结果提示，慢性缺氧对冠状血管贮备减少可能是小动脉壁增厚、外膜胶元增加和血液粘滞性增加及右心室肥大的结果。

EFFECT OF HYPOXIA ON MAXIMAL MYOCARDIAL BLOOD FLOW IN RIGHT VENTRICLE

In older to study the changes of coronary reservc capacity, the effects of hypoxia on hemodynamics and maximal myocardial blood flow in right ventricle were observed. Rats wre divided into 3 groups:normoxic group (control), acute hypoxic group and chronic hypoxic group. Maxmimal myocardial blood flow in the right ventricle was measured with 99m Tc radiolabelled frog RBC during adenosine infusion. The results showed that cardiac output, PaO 2 and oxygen delivery were decreased during acute hypoxia, but myocardial blood flow in right ventricle was increased, as compared with the control group. There were no significant change of maximal myocardial blood flow in the right ventricle in acute hypoxic rats. Hematocrit and blood viscosity at different shear rate and RV weight index were augmented, whereas oxygen delivery and myocardial blood flow became normal during chronic hypoxia. Maximal blood flow in RV was significantly decreased whereas arterial wall thickness and collagen in arterial adventitia were incrcased in chronic hypoxic rats. The above results suggest that the decreased coronary reserve might beresuled from the increascdblood viscosity, arterial wall thickness and collagen in arterial adventitia and right ventricular hypertrophy.