Drachuk K. Role of the hydrogen sulfide on heart- and blood vessels dysfunction during aging.

It was found that old rats have impairment both endothelium-dependent relaxation of smooth muscles and diastolic function of the heart. The last was confirmed by a decrease in the maximum rate of left ventricle pressure decline (dp/dtmin) by 27,4%, an increase in end-diastolic stiffness (by 2,1 times), an increase in the time constant of left ventricular relaxation (Tau g) by 1,4 times and an increase in left ventricular end-diastolic pressure (by 3,1 times). These functional disorders were accompanied by a decrease of H2S pools in the mitochondria-, homogenate of the heart and aorta tissue. It has been also revealed that a combined oxidative and nitrosative stress develops in the heart of old rats, leading to сNOS uncoupling and decline of the constitutive NO synthesis. It was found that both NaHS, HsS donor and propargylglycine (PAG), cystathionine-?-lyase-dependent pathway of H2S synthesis inhibitor, largely improves endothelium-dependent relaxation of smooth muscles (via NO action) and diastolic function in old rats. The molecular mechanisms of NaHS and PAG action include the increase of H2S pools (excepting PAG action in the aorta tissue), inhibition of the oxidative/nitrosative stress, restoration of the сNOS coupling and reduction of the constitutive NO synthesis. PAG increased H2S level in the heart tissue via compensatory stimulation of the other H2S synthesizing enzyme - 3-mercaptopyruvate sulfurtransferase.