Improvement of postischemic, contractile function by the calcium channel blocking agent nitrendipine in conscious...

The effect of the new calcium channel blocking agent, nitrendipine, on recovery of contractile function following a 10-min left anterior descending coronary artery occlusion was studied in conscious dogs instrumented with sonomicrometers in the subendocardium of ischemic and normal regions. Nitrendipine (1.0 and 2.5 micrograms/kg/min i.v.) or drug vehicle was administered 30 min prior to the onset of coronary artery occlusion and continued for 30 min following reperfusion accomplished by inflation and deflation of a vascular balloon cuff. Nitrendipine produced a dose-related reduction in arterial pressure and an increase in heart rate and left circumflex coronary blood flow velocity. At 6 h following reperfusion in control dogs (N = 8), segment shortening was significantly reduced from control levels (71 +/- 10% of control). In comparison, dogs pretreated with nitrendipine (3 micrograms/kg/min i.v.) (n = 8) had significantly greater recovery of segment shortening throughout the reperfusion period (102 +/- 10% of control at 6 h following reperfusion). The data demonstrate that pretreatment with the calcium channel blocking agent enhances the recovery of function in postischemic, reperfused, "stunned" myocardium.