Contractile function and Ca2+ transport system of myocardium in ageing.

Experiments with animals with various species-specific life span (rats, rabbits, cats, dogs) and different models (in situ heart, isolated perfused heart, isolated papillary muscle) have proved the reduction of functional capacity of the ageing heart. Diversely directional age-dependent shifts have been established involving myocardial Ca2+ transport system, i.e. an increase in the rate of Na+-Ca2+ exchange and passive Ca2+ transport across sarcolemma and a decrease in its Ca2+-binding capacity and a decrease in Ca2+ accumulation by sarcoplasmic reticulum and mitochondria (Ca2+ uptake). The experiments revealed a decrease in the Ca2+ ATPase myosin activity in the myocardium of aged animals and absence of age changes in the K+ ATPase activity. The findings obtained suggest that the development in the cardiac contractile function disorders in ageing largely depends on the age-related changes in the Ca2+ transport system.