Uchida Y, Sugimoto T
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
J Cardiovasc Pharmacol. 1987;10 Suppl 8:S49-55.
The effects of nicorandil on the phasic contractions of canine coronary smooth muscles were compared with the effects of other vasodilating agents. Phasic contractions of the smooth muscles were induced by applying 10(-2) M 3,4-diaminopyridine, a potassium channel blocker. The peak tension of phasic contractions was reduced by 10(-6) M and phasic contractions were eliminated by 10(-4) M of nicorandil. The peak tension was also reduced by 10(-8) M nitroglycerin, 10(-7) M nifedipine, and 10(-5) M W-7. Phasic contractions were eliminated by 10(-6) M nifedipine and 10(-4) M W-7, but they were not eliminated by 10(-6) M nitroglycerin. Depolarization associated with the phasic contractions was eliminated by 10(-6) M nifedipine and 10(-4) M nicorandil. These results indicate that nicorandil eliminated the phasic contractions of canine coronary smooth muscles through inhibition of depolarization, just as does nifedipine. It is likely that nicorandil inhibited depolarization through an increase in potassium conductance.
将尼可地尔对犬冠状动脉平滑肌相性收缩的作用与其他血管扩张剂的作用进行了比较。通过应用10(-2)M 3,4-二氨基吡啶（一种钾通道阻滞剂）诱导平滑肌的相性收缩。尼可地尔10(-6)M可使相性收缩的峰值张力降低，10(-4)M可消除相性收缩。10(-8)M硝酸甘油、10(-7)M硝苯地平和10(-5)M W-7也可使峰值张力降低。10(-6)M硝苯地平和10(-4)M W-7可消除相性收缩，但10(-6)M硝酸甘油不能消除。10(-6)M硝苯地平和10(-4)M尼可地尔可消除与相性收缩相关的去极化。这些结果表明，尼可地尔与硝苯地平一样，通过抑制去极化消除犬冠状动脉平滑肌的相性收缩。尼可地尔可能通过增加钾电导来抑制去极化。
