Heart rate and cardiac function curves. Their dependence on the age of the myocardium and the compliance of the ejection circuit.
Isolated, perfused hearts from 16 rats aged from 13 to 17 months were studied to examine the effects of age and of the compliance of the ejection circuit on heart rate and cardiac function curves. Heart rate was found to diminish both with age and with decreasing compliance of the ejection circuit. Cardiac function curves were also substantially modified by these two factors. It was found that old hearts adapted better to a reduced circuit compliance. This suggests that, in the intact animal, changes in the mechanical properties of the heart muscle may be an adjustment to the reduction in arterial compliance which accompanies ageing.
D000222:Adaptation, Physiological; D000375:Aging; D000818:Animals; D002302:Cardiac Output; D003331:Coronary Vessels / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D008297:Male; D009200:Myocardial Contraction; D010477:Perfusion; D051381:Rats