The Intracellular Calcium Kinetics and Action Potential in the Ventricular Myocardium of Spontaneously Hypertensive ISIA
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LEX SYSTEMS BIOPHYSICS
The Intracellular Calcium Kinetics and Action Potential in the Ventricular Myocardium of Spontaneously Hypertensive ISIAH Rats A. A. Balakina, *, O. N. Lukina, D. A. Kuznetsova, and Yu. L. Protsenkoa aInstitute
of Immunology and Physiology, Ural Branch, Russian Academy of Sciences, Ekaterinburg, 620049 Russia *e-mail: [email protected]
Received October 3, 2019; revised February 13, 2020; accepted February 25, 2020
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. Keywords: myocardium, age, hypertension, kinetics of free intracellular calcium, action potential@ DOI: 10.1134/S0006350920030021
The long-term action of hypertension is one of main issues that lead to the development of heart hypertrophy and heart failure. There are several experimental models of the development of arterial hypertension and, as a rule, the mechanisms that initiate hypertension in most of them start immediately after treatment such as injections of active substances or various ligatures. Recently, rat strains with genetically predetermined gradually developing hypertension have been developed. One strain is a widely known strain of spontaneously hypertensive rats; a second strain with inherited stress-induced arterial hypertension (ISIAH) was bred in Russia [1, 2]. It is important to study changes in the biophysical features of the myocardium of ISIAH rats during the development of hypertension. It is well known that hypertrophy is reflected in some modifications in the system of electromechanical coupling of excitation with myocardium contraction, particularly, in alterations of the duration of the Abbreviations: SHR, spontaneously hypertensive rats; ISIAH, inherited stress-induced arterial hypertension; WAG, Wistar albino Glaxo normotensive rats; WKY, Wistar-Kyoto normotensive rats; [Ca2+]i, free cytosolic calcium ions.
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