[Age-related dynamics of the contractile function of the myocardium and its relation to cardiomyocyte size]

An experimental study in rats has demonstrated that age-related decrease in basic contractility parameters of the heart muscle shows correlation with an increase in the volume of cardiomyocytes making up the muscle and a reduction of specific area under these cells' sarcolemma. Functional depression grows with age, so does heart response to changed calcium concentration in bath medium, and positive inotropic effect of high-frequency stimulation and adrenoreactivity are enhanced. Since these effects are mediated by calcium influx into the myocyte, their enhancement can be related to the fact that the capacity of sarcolemmal transport systems responsible for calcium withdrawal from the cells grows weaker with age.