L-цистеїн стимулює ендогенний синтез сірководню, пригнічує окисний стрес і відкривання мітохондріальної пори у серці старих щурів

The effect of the amino acid L-cysteine on the hydrogen sulfide content, oxidative stress indicators and kinetic characteristics of Ca2+-induced mitochondrial swelling in the heart of aged rats were investigated. Single administration to old rats of L-cysteine (121 mg/kg) was shown to suppress spontaneous and Ca2+-induced swelling of mitochondria, which manifested in a decrease in the amplitude of these processes and indicated prevention of mPTP formation in the heart. During aging, the mitochondrial pools of hydrogen sulfide decreased against the background of violation of constitutive NO synthesis, and also a significant increase of inducible and salvage NO synthesis. The use of L-cysteine resulted in an increase of 2.56-fold the content of hydrogen sulfide in the mitochondria of the heart of old rats (6.015 ± 0,74 nmol/mg protein) compared to animals without the introduction of the amino acid (2.35 ± 0,25 nmol/mg protein). Hence, under these conditions, the synthesis of hydrogen sulfide in the mitochondria was restored, probably due to the activation of H2S-synthesizing enzymes by their substrate, which contributed to significant inhibition of inducible NO synthesis by 1.73 times and a decrease by 2 times of nitrate reductase and arginase activity. The introduction of L-cysteine to old animals significantly (1.5 times) reduced uric acid pools, which may indicate suppression of superoxide radicals formation, and significantly decreased pools of diene conjugates (7 times), which indicates the suppression of oxidative stress in the early stages of lipid peroxidation. Thus, the results of studies indicate the participation of L-cysteine in the stimulation of endogenous hydrogen sulphide synthesis in mitochondria, which contributes to the reduction of oxidative stress in organelles and modulation of changes in the permeability of mitochondrial membranes. This fact speaks to the importance of such a gas transmitter as hydrogen sulphide, as a regulatory factor in the cardiovascular system, which modulates the functions of cells and their organelles. [ABSTRACT FROM AUTHOR]