Action of anti-anginal drugs on cardiac metabolism

Diltiazem, a calcium antagonist, was found to lessen the effect of ischemia resulting from coronary occlusion in dogs. For example, this agent preserves the high energy phosphate reservoir and decreases the inhibition of glycolytic flux at the phosphofructokinase level caused by myocardial ischemia. Diltiazem produced a marked reduction in ischemia-induced damage to the contractile elements. Increased tissue levels of lactate and free fatty acids attributable to ischemia were lowered by diltiazem. Although diltiazem increased contractility of isolated ischemia heart muscle fibers, it did not lessen the effect of ischemia on mitochondrial respiration or mitochondrial calcium binding. On the other hand, diltiazem was found to counteract the effects of ischemia followed by reperfusion on mitochondrial oxygen consumption and calcium binding.