Omvik P, Lund-Johansen P, Haugland H
Medical Department, Haukeland Hospital, Bergen, Norway.
J Hypertens. 1988 Feb;6(2):95-103.
Calcium blockers may reduce contractility of vascular smooth muscle as well as that of myocardial cells. Therefore, falls in both total peripheral vascular resistance (TPR) and cardiac output (CO) might be responsible for a fall in blood pressure (BP) caused by calcium blockers in essential hypertension. We have studied the acute and chronic haemodynamic effects of nisoldipine (a new calcium blocker) in 19 patients with essential hypertension at rest in the supine and sitting positions and during 100-W dynamic exercise to investigate whether CO might be compromised by acute and chronic calcium blockade. Intra-arterial pressure, CO (by Cardiogreen), stroke volume, heart rate and TPR were measured hourly after the first dose of 10 mg nisoldipine (acute study) and then after 1 year of nisoldipine treatment (mean dose 25 mg; chronic study). The maximal first dose response was seen after 1 h, i.e. a fall in intra-arterial pressure (9%) and TPR (19%) and a reflex rise in heart rate (9%) and CO (12%). The effects levelled off during the next 2 h. After 1 year of treatment there was a more marked reduction in BP: at rest intra-arterial pressure fell (14% supine, 16% sitting) due to fall in TPR (19%) but without significant changes in heart rate or CO; during 100-W exercise, intra-arterial pressure fell (14%) due to reduction in both TPR (7%) and CO (6%). In conclusion, nisoldipine lowers BP by reducing TPR, both acutely and chronically. The initial reflex tachycardia and rise in CO disappear during long-term treatment, probably due to resetting of the baroreceptors.(ABSTRACT TRUNCATED AT 250 WORDS)
钙通道阻滞剂可能会降低血管平滑肌以及心肌细胞的收缩性。因此，总外周血管阻力（TPR）和心输出量（CO）的下降可能是钙通道阻滞剂导致原发性高血压患者血压（BP）下降的原因。我们研究了尼索地平（一种新型钙通道阻滞剂）对19例原发性高血压患者在仰卧位和坐位静息状态下以及100瓦动态运动时的急性和慢性血流动力学影响，以探讨急性和慢性钙通道阻滞是否会损害心输出量。在首次服用10毫克尼索地平后（急性研究），然后在尼索地平治疗1年后（平均剂量25毫克；慢性研究），每小时测量动脉内压力、心输出量（通过心绿素）、每搏输出量、心率和总外周血管阻力。最大的首次剂量反应在1小时后出现，即动脉内压力下降（9%）和总外周血管阻力下降（19%），心率反射性升高（9%）和心输出量升高（12%）。在接下来的2小时内，这些效应趋于平稳。治疗1年后，血压下降更为明显：静息时，由于总外周血管阻力下降（19%），动脉内压力下降（仰卧位14%，坐位16%），但心率或心输出量无显著变化；在100瓦运动期间，由于总外周血管阻力（7%）和心输出量（6%）均下降，动脉内压力下降（14%）。总之，尼索地平通过降低总外周血管阻力，在急性和慢性情况下均能降低血压。长期治疗期间，最初的反射性心动过速和心输出量升高消失，可能是由于压力感受器重新设定所致。（摘要截选至250字）
