Messing M, Van Essen H, Smith T L, Smits J F, Struyker-Boudier H A
Department of Pharmacology, University of Limburg Medical School, Maastricht, The Netherlands.
Eur J Pharmacol. 1991 Jun 6;198(2-3):189-95. doi: 10.1016/0014-2999(91)90620-6.
The microvascular actions of three calcium channel antagonists were studied in intact spontaneously hypertensive rats (SHR) provided with a dorsal striated muscle microcirculatory chamber. Verapamil and the dihydropyridine derivatives nifedipine and felodipine reduced mean arterial blood pressure (MAP) in a dose-dependent manner. They dilated arterioles of different sizes, with the most pronounced effect being on the smallest precapillary arterioles. Venular diameters were not affected by the calcium antagonists. Approximately 60% of the small arterioles showed a rhythmic pattern of vasodilatation and constriction. This pattern of spontaneous vasomotion was completely blocked by the calcium channel antagonists, especially those of the dihydropyridine type. It is concluded that (a) small precapillary arterioles play an important role in the vasodilator action of calcium channel antagonists, and (b) arteriolar vasomotion depends on vascular smooth muscle cell calcium influx.
利用背侧横纹肌微循环室，在完整的自发性高血压大鼠（SHR）中研究了三种钙通道拮抗剂的微血管作用。维拉帕米以及二氢吡啶衍生物硝苯地平和非洛地平以剂量依赖方式降低平均动脉血压（MAP）。它们使不同大小的小动脉扩张，对最小的毛细血管前小动脉的作用最为明显。钙拮抗剂对小静脉直径无影响。约60%的小动脉呈现血管舒张和收缩的节律模式。这种自发性血管运动模式被钙通道拮抗剂完全阻断，尤其是二氢吡啶类拮抗剂。得出以下结论：（a）毛细血管前小动脉在钙通道拮抗剂的血管舒张作用中起重要作用；（b）小动脉血管运动依赖于血管平滑肌细胞的钙内流。
