Pedrinelli R, Taddei S, Salvetti A
Hypertension Unit, I Clinica Medica, University of Pisa, Italy.
Clin Pharmacol Ther. 1989 Mar;45(3):285-90. doi: 10.1038/clpt.1989.30.
The interference by two unrelated calcium entry blockers, nicardipine and verapamil, with the forearm vascular response to graded exogenous norepinephrine was evaluated in two groups (n = 6 each) of patients with uncomplicated hypertension. Drugs were infused into the brachial artery at systemically ineffective rates and forearm blood flow was measured by venous plethysmography. Nicardipine (1 microgram/dl forearm tissue/min) relaxed forearm arterioles and antagonized the vasoconstrictor effect of norepinephrine, whereas verapamil (1 microgram/dl forearm tissue/min) was ineffective, although vasodilating to a comparable extent. Therefore, functional alpha-antagonism may contribute to the vasodilating and, possibly, the antihypertensive effect of nicardipine but, apparently, not verapamil. The data further stress the heterogeneity of calcium channel entry blockers even in human beings.
在两组（每组n = 6）无并发症高血压患者中，评估了两种不相关的钙通道阻滞剂尼卡地平和维拉帕米对前臂血管对分级外源性去甲肾上腺素反应的干扰。以全身无效的速率将药物注入肱动脉，并通过静脉体积描记法测量前臂血流量。尼卡地平（1微克/分升前臂组织/分钟）使前臂小动脉舒张，并拮抗去甲肾上腺素的血管收缩作用，而维拉帕米（1微克/分升前臂组织/分钟）虽然在相当程度上具有血管舒张作用，但却无效。因此，功能性α拮抗作用可能有助于尼卡地平的血管舒张作用以及可能的降压作用，但显然对维拉帕米无效。这些数据进一步强调了即使在人类中钙通道阻滞剂的异质性。
