硝基甘油对狗缺血区冠脉循环的作用

用实验性犬冠脉狭窄模型,冠脉内恒流灌注硝基甘油0.5μg/kg.min^-1,使冠脉血流量(CBF)增加、远端小动脉压(DCP)、冠脉血管总阻力(R_T)、小冠脉血管阻力(R_S)及冠状静脉低切血粘(η_b)减少;而主动脉压和心率无明显变化。恒流灌注硝基甘油1μg/kg.min^-1时,在开始5min内冠脉循环的变化同上,并伴大冠脉血管阻力(R_L)减少,10 min后出现CBF减少和R_T,R_{L及ηb增加。结果提示,硝基甘油有缓解和加重心肌缺血的双重作用,其作用可能与剂量张扩张远端小动脉压的程度有关。}

EFFECT OF NITROGLYCERIN ON CORONARY CIRCULATION OF THE ISCHEMIC REGION IN DOGS

The purpose of this study was to define the effects of nitroglycerin on coronary circulation in ischemic region. In 18 open chest dogs, a critical stenosis of the left anterior descending coronary artery was produced by an external micrometer constrictor. Intracoronary infusion of nitroglycerin 0.5 micrograms/kg. min-1 increased coronary blood flow (CBF) and decreased distal coronary pressure (DCP), total coronary artery resistance (RT), small coronary artery resistance (RS); but did not affect mean aortic pressure, heart rate and large coronary artery resistance (RL). The whole blood viscosity in coronary vein was reduced. Intracoronary infusion of nitroglycerin 1 microgram/kg.min-1, CBF increased and RT, RL, RS, DCP decreased during the first 5min. Then the CBF decreased, RT and RL increased. These were associated with a decrease in DCP and an increase in whole blood viscosity. A passive narrowing of the stenotic area was observed. These results indicate that nitroglycerin has two effects on coronary circulation, it can increase CBF and decrease coronary artery resistance in relieving myocardial ischemia; it can also decrease CBF and cause passive narrowing of coronary artery in worsing myocardial ischemia. The beneficial or harmful effect of nitroglycerin may depend on its doses and DCP.