Ultrastructural changes in cardiomyocyte mitochondria during regenerative and plastic insufficiency of the myocardium.

Daunomycin-induced regenerative and plastic insufficiency of the myocardium was accompanied by accumulation of cardiomyocytes with unstable mitochondrial membranes containing enlarged mitochondria with lightened matrix and fragmented cristae. Total destabilization of mitochondrial membranes was found in cardiomyocytes with most pronounced ultrastructural signs of impaired protein synthesis. These changes in mitochondria were permanent, which suggested that swelling and destruction of cristae were related to intravital decrease in mitochondrial membrane stability.