[Effect of dobutamine and diltiazem on the reperfused ischemic myocardium]

Twenty-two anesthetized open-chest mongrel dogs were studied to evaluate the effect of dobutamine, dobutamine and diltiazem on the ischemic-reperfused myocardium assessed by cardiac function, myocardial metabolism such as tissue ATP, Ca and water content and ultrastructure. The left anterior descending coronary artery was ligated for 40 minutes and then reperfused for 15 minutes. Experiments were divided into 3 groups by infusion of physical saline solution (C), dobutamine 5 micrograms/kg/m in (DOB) and dobutamine 5 micrograms/kg/min+diltiazem 0.1mg/kg bolus IV at the beginning of reperfusion and followed by continuous infusion with 30 micrograms/kg/min (DOB+D) during reperfusion period. DOB increased SAP and CI, however it also increased heart rate. CI, LVSWI and coronary blood flow in non ischemic area increased significantly in DOB+D than either C or DOB. Myocardial ATP in the ischemic endocardium was much more preserved in DOB and DOB+D than C. Myocardial Ca and water content were lower level in DOB+D, but not significantly different among 3 groups. Mitochondrial score by Sunamori's method in DOB+D was higher than that in C (p less than 0.05). These results suggest that low dose of dobutamine during reperfusion is effective to enhance hemodynamic parameters without deterioration of myocardial metabolism, and furthermore combined use of dobutamine and diltiazem is more effective to protect myocardial metabolism and ultrastructure from reperfusion damage in addition to improvement of hemodynamic parameters.