Gelpi R J, Mosca S M, Rinaldi G J, Kosoglov A, Cingolani H E
Am J Physiol. 1983 Mar;244(3):H378-86. doi: 10.1152/ajpheart.1983.244.3.H378.
The cardiovascular effects of prenylamine (P), verapamil (V), and nifedipine (N) were studied in open-chest, anesthetized dogs and in isolated, isovolumic dog hearts perfused at constant coronary blood flow (CBF). These drugs significantly decreased left ventricular pressure (LVP) and its maximal rates of rise (+P) and fall (-P). The tension developed by an isometric segment of the left ventricle and its maximal rates of rise (+T) and fall (-T) also decreased, whereas heart rate (HR) did not show statistically significant differences. Maximal rates of fall (-P and -T) were proportionally more depressed than maximal rates of rise (+P and +T), producing significant increments in the ratios between both maximal velocities (+P/-P and +T/-T). The time constant of LVP isovolumic decay tau was significantly prolonged, either in the whole animal or in isolated perfused hearts. The afterload reduction produced by the compounds can account in part for the increase in +P/-P but not for the increase in +T/-T or for the prolongation of tau. These relaxation indices remained unchanged after comparable myocardial depressions elicited by d,l-propranolol or pentobarbital sodium. It is concluded that calcium antagonist compounds are characterized by an "antirelaxant" effect, not explained by changes in HR, CBF, or loading conditions, and independent from their negative inotropic action.
在开胸麻醉犬以及在以恒定冠状动脉血流量（CBF）灌注的离体等容犬心脏中研究了普尼拉明（P）、维拉帕米（V）和硝苯地平（N）对心血管的影响。这些药物显著降低左心室压力（LVP）及其最大上升速率（+P）和下降速率（-P）。左心室等长节段产生的张力及其最大上升速率（+T）和下降速率（-T）也降低，而心率（HR）未显示出统计学上的显著差异。最大下降速率（-P和 -T）比最大上升速率（+P和 +T）成比例地降低得更多，导致两个最大速度之间的比率（+P/-P和 +T/-T）显著增加。无论是在整个动物还是在离体灌注心脏中，LVP等容衰减的时间常数tau都显著延长。这些化合物产生的后负荷降低可以部分解释 +P/-P的增加，但不能解释 +T/-T的增加或tau的延长。在由d，l-普萘洛尔或戊巴比妥钠引起的相当程度的心肌抑制后，这些舒张指数保持不变。得出的结论是，钙拮抗剂化合物的特征是具有“抗舒张”作用，这不能通过心率、CBF或负荷条件的变化来解释，并且与其负性肌力作用无关。
