EMD_(56431)对犬冠脉和肠系膜动脉的作用

Action of EMD_(56421) on isolated canine coronary and mesenteric arteries

目的 :研究EMD对犬冠脉和肠系膜动脉的松弛作用。方法 :用 2 0和 60mmol/LKCl激动冠脉 ( +E ,-E) ,观察EMD的松弛效应。同时观察格列本脲对EMD松弛冠脉的影响及EMD对KCl量效曲线的改变。此外 ,还测定了EMD松弛犬肠系膜动脉和冠脉的EC50 。结果 :0 .7μmol/LEMD对 2 0mmol/LKCl去极化冠脉 ( +E ,-E)呈非内皮依赖性松弛 ,而对 60mmol/LKCl去极化冠脉无效 ;格列本脲能有效拮抗EMD对冠脉的松弛作用 ;EMD使 5～3 0mmol/LKCl去极化冠脉量效曲线呈非平行右移 ,但对 4 0mmol/L以上浓度KCl去极化冠脉则失去拮抗作用 ,最大反应 (Emax)不压低。EMD松弛犬肠系膜动脉和冠脉的EC50 ( -logc)分别为 6.2和 6.4 4。结论 :EMD为非内皮依赖性血管平滑肌松弛剂 ,对冠脉的松弛作用约为肠系膜动脉的 2倍。

OBJECTIVE:To investigate the relaxant action of EMD on isolated canine coronary and mesenteric arteries.METHODS:20 and 60mmol/L KCl were used to pre constricted coronary artery rings with or without endothelium,and relaxant response of EMD was observed.In the presence of glibenclamide,the vasolaxant response to EMD in KCl pre constricted coronary artery was studied and the change of EMD on the dose response curves for KCl induced coronary artery constriction was observed.In addition,EC 50 of EMD on coronary and mesenteric arteries was measured.RESULTS:In the canine coronary artery rings with or without endotelium,0.7μmol/L EMD caused significant relaxant response of to pre constricted coronary artery with 20mmol/L KCl.When coronary artery was pre constricted with 60mmol/L KCl,relaxant effect of EMD was abolished.In the presence of glibenclamide,the vasolaxant response for EMD in KCl pre contracted coronary artery was antagonized significantly.EMD shifted the dose response curves for KCl(5～30mmol/L) induced constriction to the right,but it had no antagonized response to higher concentration of KCL(≥40mmol/L)(E max was not lowered).EMD produced a markedly concentration dependent reduction of contractile response to phenylephrine or KCl in coronary and mesenteric arteries,their -logEC 50 values were 6.20 and 6.44 respectively.CONCLUSION:EMD is a non endothelium dependent preparation for vascular smooth muscles relaxation,the relaxing action of EMD on mesenteric artery is two times that of coronary artery.