The Intracellular Calcium Kinetics and Action Potential in the Ventricular Myocardium of Spontaneously Hypertensive ISIAH Rats

Abstract

Here, we show the dependence of intracellular calcium kinetics and the duration of the action potential of cardiomyocytes on an animal’s age in multicellular preparations of the myocardium of the left and right ventricles of healthy control rats and rats with inherent arterial hypertension. In the myocardium samples from control or hypertensive rats the kinetics of the decline of free intracellular calcium slows with age and the differences between the groups become minimal. The short-term deceleration phase of intracellular calcium decline, which is clearly seen in the right ventricle of young hypertensive rats, is smoothed. The duration of the repolarization phase in cardiomyocytes of both ventricles of rats of the control and hypertensive groups shortens; however, it is always higher in the right ventricle samples of control rats with respect to that in the myocardium of hypertensive rats. Here we show the age-related changes in some features of the electromechanical coupling in the myocardium of rats with inherited arterial hypertension for the first time. These experimental data demonstrate the development of spontaneous hypertrophy probably induced by activation of the renin–angiotensin system.