Book of Abstracts - New Frontiers 2022

Abstracts of poster presentations

CALCIUM TRANSIENTS IN CARDIOMYOCYTES OF SEDENTARY AND ACTIVE RATS

I. Baglaeva, M. C agalinec, B. Iaparov, A. Zahradníková, A. Zahradníková Jr.

Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia

The key process of myocardial function is the excitation-contraction coupling (ECC) by which the electrical excitation triggers mechanical contraction of the heart. The coupling agent in cardiac ECC are calcium ions, which also regulate the contraction of myocytes. Therefore, the final performance of cardiac muscle depends on the proper balance of all these components. Physical exercise influences the cardiac output in all mammals [1]; however, the exact mechanisms are not sufficiently understood neither in physiological nor in pathological conditions. We inspected differences between the sedentary and voluntarily running rats in kinetic parameters of calcium transients in isolated cardiomyocytes. The rats were housed in individual cages with or without access to a running wheel. After two weeks, animals were euthanized, and left ventricular cardiomyocytes were isolated using standard procedures [2]. Changes in the intracellular calcium concentration were recorded using laser scanning fluorescence confocal microscopy in the line scan mode as transient changes in fluorescence of the calcium sensitive dye Fluo-3. Recorded cardiomyocytes were field stimulated at frequency of 1.0 Hz for about 60 seconds and then recorded for further 20 seconds. The amplitude (ΔF/F0) and the kinetic parameters of individual calcium transients in the recorded traces - the time to peak (TTP), the rise time (20-80%), the decay time (80-20%), and the duration at half-amplitude (FDHM) - were determined from fluorescence signals using custom software. The software identified individual transients, fitted their time course, and reported the parameters in a sequence of automatic algorithms. The verification on theoretical model traces provided reliable estimation of the model parameters in a broad range of signal-to-noise ratios. Preliminary analysis of the dataset of 8 cardiomyocytes from two animals revealed a tendency for acceleration in all kinetic parameters of calcium transients in cardiomyocytes of rats with access to voluntary running. The distribution of the parameter estimates showed occasional deviation from the normal distribution and a large variation between individual myocytes isolated from the same animal. The parameter FDHM was distributed normally, with a significantly shorter duration in the exercising group. These preliminary results suggest that even two weeks of voluntary exercise may affect parameters of calcium signalling in the rat ventricular myocytes, although the final conclusion will need verification and expansion of the recorded dataset. Analysis of further data is ongoing. [1] M. A. Nystoriak and A. Bhatnagar, Front Cardiovasc Med. 5 (2018), 135. [2] M. Cagalinec, A. Zahradníková, A. Zahradníková, Jr. et al., Front Physiol. 10 (2019), 172.

Keywords: cardiac myocytes, calcium transients, voluntary exercise

Funding:The research was supported by the grants SAV-TUBITAK JRP/2019/836/RyRinHeart, VEGA 2/0182/21, and IMTS: 313011V344.

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