[The effect of diltiazem and dobutamine on myocardial ischemia]

The effect of diltiazem and dobutamine on cardiac function and metabolism of the myocardium rendered ischemic for 40 min by occlusion of the left anterior descending coronary artery followed by 15 min reperfusion were studied in 22 dogs. In group D, diltiazem was administered in 8 dogs by a 0.1 mg/kg iv bolus followed by 30 micrograms/kg/min continuous infusion. In D-D group, dobutamine was infused at 5 micrograms/kg/min during reperfusion in 8 dogs. Diltiazem was used in the same manner as group D. Cardiac output was much higher in group D than in the non-treated group C, and heart rate, double product, SVR were reduced but coronary flow was increased in group D. Myocardial tissue Ca2+ in group D was significantly lowered level as compared to group C. Myocardial ATP and CP content were much better preserved in group D than in group C. In group D-D, dobutamine enhanced cardiac function without depletion of myocardial high-energy phosphate but tissue Ca2+ was slightly increased. Myocardial ischemic changes in the ultrastructure were much better protected in group D and D-D than in group C. In group C and D-D, reperfusion-induced arrhythmias were significantly reduced.