Effect of actinomycin D and cycloheximide on experimental myocardial infarction in rats.

Actinomycin D, an inhibitor of DNA-directed RNA synthesis, or cycloheximide, a protein synthesis inhibitor, administered 24 h and 1 or 4 h respectively, before inducing coronary occlusion in conscious rats, offered marked protection against postinfarction ventricular fibrillation and sudden death. When actinomycin D was given 4 h prior to coronary ligation, the outcome of myocardial infarction was not influenced, the well-established cardioprotective effect of dexamethasone was however completely abolished. These results suggest that protein factors may be involved in the early events of myocardial infarction.