Effect of Mechanical Stretching of the Right Atrium of Isolated Rat Heart on Dispersion of Repolarization before Fibrill
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Bulletin of Experimental Biology and Medicine, Vol. 169, No. 4, August, 2020 GENERAL PATHOLOGY AND PATHOPHYSIOLOGY
Effect of Mechanical Stretching of the Right Atrium of Isolated Rat Heart on Dispersion of Repolarization before Fibrillation E. E. Kharkovskaya, O. V. Drugova, G. V. Osipov, and I. V. Mukhina
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 169, No. 4, pp. 419-421, April, 2020 Original article submitted November 29, 2019 The multi-electrode mapping method was used to analyze electrical activity of isolated rat heart under conditions of standard perfusion, pharmacological stimulation of fibrillation, and mechanical stretching of the right atrium both under normal conditions and before cardiac fibrillation. It was shown that stretching of the right atrium prevented the increase of repolarization dispersion and latency of the electrical signal in the myocardium that were observed before cardiac fibrillation. Key Words: isolated heart; fibrillation; mechanical stretching Cardiac fibrillation is a dangerous condition that can cause sudden cardiac death. It is not well understood and can be induced by a number of factors [6]. It is believed that the development of fibrillation is preceded by a decrease in the electrical conductivity of the myocardium and an increase in dispersion of repolarization (DR) [3,7]. The multi-electrode mapping method allows carrying out a comparative analysis between the activation times and times of repolarization on the electrodes of the matrix. Thus, it becomes possible to evaluate such parameters as DR and latency of the electrical signal (LES) that characterizes the speed of the electrical signal on the surface of the myocardium. In our experiments and in studies of other authors [12], artificially synthesized chemical 2-aminoethoxydiphenyl borate (2-apb) affecting intracellular calcium conductivity and the state of gap junctions in the myocardium [4,5,8,10] induced the development of fibrillation of the isolated rat heart. Mechanical stretching of the right atrium (RA) and sinus node area can affect the state of mechanosensitive ion channels of cardiomyocytes, cytoskeleton proteins, and extracellular matrix [9,11,13]. Due to the function of the intracardiac nervous system [1], National Research N. I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia. Address for correspondence: [email protected]. E. E. Kharkovskaya
mechanical influences on RA can modulate the electrophysiological response in other parts of the heart. The purpose of this study was to assess changes in the parameters of electrical activity of the isolated heart (DR and LES) before fibrillation and during mechanical stretching of RA under normal physiological conditions and under conditions that provoke fibrillation. These data can contribute to better understanding of the fundamental electrophysiological processes occurring in this situation and complementarity of intracardiac signaling mechanisms aimed at heart adaptation to changes in external conditions
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