Reserpine: effect on structure of heart muscle.

We examined the ultrastructure of hearts from dogs given reserpine intramuscularly for 4 days, and from untreated dogs. Sections of the myocardium from treated dogs invariably revealed mitochondrial abnormalities at the 5th and 14th days. These included fragmentation and loss of structure of the cristae, and cyst formation. The appearance at 25 days in the treated as well as in all the untreated dogs was normal. We concluded that reserpine in the dose used produces marked structural changes in the mitochondria of heart muscle, and that these changes are reversible. These changes may account for the myocardial depression sometimes seen after administration of reserpine.