| Summary: | Hydrogen sulfide is signalling molecule that regulates vascular tone and myocardial contractility. Role of estradiol in hydrogen sulfide production in cardiovascular system of rats remains unclear and this becames research objective. Effect of estradiol on hydrogen sulfide level, cystathionine-γ -lyase activity and its kinetic parameters - Michaelis constant (Km) and maximum rate (Vmax) in rats’ heart was estimated. Experiments were conducted on 45 white nonlinear female rats. Deficit of sex hormones level in females was modulated by castration - ovariectomy and hormone replacement therapy with estradiol. It is shown that the production of hydrogen sulfide in the myocardium is determined by the level of estradiol: castration of females causes a significant decrease in myocardial hydrogen sulfide content, cystathionine-γ-lyase activity, maximum rate of hydrogen sulfide formation from cysteine in participation of cystathionine-γ-lyase, as well as increase in Michaelis constant of this enzyme in comparison with the controls. Hormone replacement therapy with estradiol brings nearer hydrogen sulfide level, cystathionine-γ-lyase activity and kinetic parameters of cysteine desulfuration reaction in the rats’ myocardium to the levels of the control group. Thus, estradiol is involved in regulation of hydrogen sulfide production in cardiovascular system of rats, namely it increases cystathionine-γ-lyase activity and its affinity to cysteine.
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