[CA²⁺ ACCUMULATION IN ISOLATED RAT HEART MITOCHONDRIA UNDER MAINTENANCE OF MITOCHONDRIAL POTENTIAL].

It is known that mitochondria can accumulate calcium, which regulates energy metabolism and cell death. About 90% of energy of cardiomyocytes is synthesized in mitochondria. Heart cells are also affected by the rapid changes in the Ca²⁺ concentration in the cytoplasm.

[Effect of hydrogen sulfide donor NaHs on the functional state of the respiratory chain of the rat heart mitochondria].

In experiments on mitochondria isolated from the heart tissue of adult rats we studied the effects of a donor of hydrogen sulfide, NaHS, on the respiratory chain of the organelles. We found that NaHS (10(-9)-10(-6) mol/l) caused a dose-dependent decrease in the rate of oxygen consumption in the presence of succinate and ADP (state 3 to Chance), and in the absence of ADP (state 4). The decrease in the rate of oxygen consumption in a concentration NaHS 10(-9) mol/l and 10(-8) mol/l associated with an increased conjugation of oxidation and phosphorylation, as evidenced by the increase in the respiratory control, the efficiency of oxidative phosphorylation (ADP/O) is not changed.

[New fluorine-containing openers of ATP-sensitive potassium channels flokalin and tioflokalin inhibit calcium-induced mitochondrial pore opening in rat hearts].

In experiments in vitro on the mitochondria isolated from the rat's heart we studied the effects of the openers of ATP-sensitive potassium channels (K(ATP)-channels), flocalin and tioflocalin, on the calcium-induced mitochondrial pore (MPTP) opening. Flocalin and tioflocalin caused moderate Ca(2+)-independent mitochondria swelling, which was prevented by a specific inhibitor of 5-hydroxydecanoate. This allowed to identify these compounds as mitochondrial K(ATP)-channels openers.

[The effect of hydrogen sulfide on contractile activity of the vascular smooth muscles in rats].

The effect of endogenous and exogenous hydrogen sulfide (H2S) on contractile activity of vascular smooth muscle (VSM) was studied. The introduction of substrate synthesis H2S L-cysteine and its donor NaHS in vitro caused concentration-dependent relaxation of VSM of aorta and portal vein. Low concentrations of hydrogen sulfide donor (10(-5) mol/L) caused vasoconstriction of both types of the vessels.

[Hydrogen sulfide inhibits Ca(2+)-induced mitochondrial permeability transition pore opening in adult and old rat heart].

In experiments in vivo and in vitro on the mitochondria isolated from adult and old rat hearts, we studied the effects of a donor of hydrogen sulfide (H2S), NaHS, and H2S biosynthesis substrate, L-cysteine, on the sensitivity of the mitochondrial permeability transition pore (mPTP) opening to its natural inductor, Ca(2+). We found that NaHS (10(-12) to 10(-4) mol/l) influenced mitochondrial swelling in a concentration-dependent manner. It was also demonstrated that the addition of NaHS (10(-12) to 10(-8) mol/l) to the calcium-free medium resulted in moderate a swelling of mitochondria from both adult and old rat hearts.