[Calcium-binding activity of heart mitochondria in the aging rat and its possible role in myofibril relaxation].

Ca2+-binding activity of heart mitochondria does not change with aging of rats. The results are discussed in terms of experimental mitochondrial involvement in the control of myocardial contractility with regard to the reported data on the increased period of myocardial relaxation and diminution of the myocardium mitochondrial content during aging.