Kushiro Toshio, Watanabe Nagaoki, Takahashi Atsuhiko, Koike Miyuki, Saito Fumio, Otsuka Yuji, Kanmatsuse Katsuo
Department of Cardiology, Nihon University Surugadai Hospital, Tokyo, Japan.
J Cardiovasc Pharmacol. 2004 Dec;44(6):672-5. doi: 10.1097/00005344-200412000-00008.
Dihydropyridine calcium channel blockers are not uniform in terms of their action on calcium channel. L-type calcium channel blockers dilate the resistance arterioles. Cilnidipine is a dihydropyridine calcium channel blocker that also acts on N-type calcium channels, and may dilate venules through its effect on the sympathetic receptor. The influence of an L-type calcium channel blocker (nifedipine) or this L+N type blocker at 10(-7) mol to 10(-4) mol on venular diameter was examined by superfusion of male Syrian hamster cheek pouches. Nifedipine dose dependently dilated the arterioles alone, whereas cilnidipine dilated both arterioles and venules. Application of 10(-7) mol omega conotoxin, an inhibitor of N-type channels, after nifedipine led to significant dilation of venules, while it had no influence when administered after cilnidipine. These findings indicate that the effects of calcium channel blockers on the venules differ according to the action on N-type calcium channels, and that cilnidipine (an L+N type calcium channel blocker) dilates venules through its additional action on N-type channels.
二氢吡啶类钙通道阻滞剂对钙通道的作用并不一致。L型钙通道阻滞剂可扩张阻力小动脉。西尼地平是一种二氢吡啶类钙通道阻滞剂，它也作用于N型钙通道，并且可能通过其对交感神经受体的作用来扩张小静脉。通过对雄性叙利亚仓鼠颊囊进行灌流，研究了10^(-7)摩尔至10^(-4)摩尔的L型钙通道阻滞剂（硝苯地平）或这种L+N型阻滞剂对小静脉直径的影响。硝苯地平单独作用时剂量依赖性地扩张小动脉，而西尼地平则同时扩张小动脉和小静脉。在硝苯地平之后应用10^(-7)摩尔的ω-芋螺毒素（一种N型通道抑制剂）可导致小静脉显著扩张，而在西尼地平之后给药则没有影响。这些发现表明，钙通道阻滞剂对小静脉的作用因对N型钙通道的作用不同而有所差异，并且西尼地平（一种L+N型钙通道阻滞剂）通过其对N型通道的额外作用来扩张小静脉。
