Regular exercise increases H2S levels in mitochondria and cardiac tissue, enhances genes expression of H2S-synthesizing enzymes and prevents mitochondrial swelling
Authors: Luchkova AY , Mys LA , Strutynska NA , Sagach VF 
Published: June 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
It is known that regular exercise is important and very useful for the cardiovascular system because of decreasing the incidence of myocardial infarction and protection against chronic and acute coronary disease. It normalizes blood pressure, lowers weight, reduces vascular resistance and enhances structural adaptations through increasing number of capillaries and arteries. It was also shown that exercise has a positive effect on vasodilatation by increasing nitric oxide (NO) production via eNOS gene expression enhancing. As we know hydrogen sulfide (H2S) is also a gaseous molecule that performs many functions in the cardiovascular system. It was found that disorders of H2S synthesis are found during hypertension, atherosclerosis, diabetes, heart failure, neurodegenerative diseases and aging.

Purpose
The aim of this study was to investigate the effect of moderate exercise on endogenous H2S content, gene expression levels of H2S-synthesizing enzymes and opening of mitochondrial pore in adult and old rats.

Methods
We used adult (5-7 months) and old (22-24 months) Wistar male rats. Physical training of adult and old animals was carried out 5 days a week by forcibly swimming for six and four weeks, respectively. The first training session of adult and old rats lasted 2 minutes and the duration was increased by 4 and 2 minutes every other day respectively. Mitochondria were isolated by differential centrifugation method. H2S was determined in mitochondria and heart tissues by biochemical method using zinc acetate, N,N-DPD and FeCl3. H2S-synthesizing enzymes genes were defined by real-time PCR using TaqMan Master Mix and primers for CSE and 3-MST.

Results
In our experiments we showed that physical training increases the H2S level in mitochondria and heart tissue of adult and old animals. The concentration of H2S in mitochondria enhances by 2,3 times for adult (4,58±0,3 nmol/mg compare to 10,55 ±1,18 nmol/mg, Р&lt;0,05) and by 8,8 times for old rats (2,38±0,45 nmol/mg compare to 20,91 ±3,56 nmol/mg, Р&lt;0,05). A slight increase in these indicators was also observed in the heart tissue of both groups. It should be noted that in old animals initially H2S level was decreased twice compared to adult. At the same time the levels of H2S-synthesizing enzymes, CSE and 3-MST, was lowered by 4 and 3 times in old rat heart. Exercise increases levels of these genes by 2,6 and 3 times for adult cardiac tissue and 7,9 and 7,2 times for old heart tissue. Physical training also has positive effect on mitochondrial pore opening and reduces ROS generation in the heart of old animals. Thus, Ca2+-induced mitochondrial swelling decreased by 37% in adult and 26% in old rat cardiac tissue, and the rate of O2- generation by 85% compared to untrained rats.

Conclusion
Physical training increases H2S levels, genes expression of H2S-synthesizing enzymes in mitochondria and cardiac tissue and prevents mitochondrial permeability transition opening in adult and old rats.