[Biochemical mechanisms of the cardioprotective effect of the K(ATP) channels opener flocalin (medicinal form) in ischemia-reperfusion of myocardium].

In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min) of myocardium it was investigated changes of biochemical processes in arterial blood at intragastric introduction of medicinal form (tablets) of flocalin (the fluorine-containing opener of ATP-sensitive potassium channels) in a dose 2,2 mg/kg. The data analysis allowed to define a few possible mechanisms of cardioprotective action offlocalin, which prevented the opening of a mitochondrial permeability transition pore (MPTP) and inhibition of apoptosis induced by it. They consist, from one side, in activating of the constitutive de novo biosynthesis of nitric oxide by cNOS, from other side, in suppression of inducible nitric oxide de novo synthesis by iNOS in such way to prevent the formation of toxic peroxynitrite by co-operation of surplus nitric oxide with superoxide anion, thereby limits the generation of toxic active forms of nitrogen (*NO2) and oxygen (*OH). The first effect of flocalin takes place due to limitation the degradation of L-arginine by arginase which keeps substrat for cNOS, second--due to the inhibition of superoxide generation, in particular, by xanthine oxidase (marker uric acid), lipoxigenase (marker LTC4) and cyclooxygenase (marker TxB2). Because LTC4 have coronaroconstrictory, arrhythmogenic and chemoattractory properties in the conditions of myocardial ischemia, inhibition of its production both with superoxide generation (markers H2O2 and diene conjugates) may be the another mechanisms of flocalin's cardioprotection. Powerful antiischemic action of flocalin (marker nitrite anion) as the mechanisms of cardioprotection is possible as well as inhibition of ATP and GTP degradation (marker hypoxanthine+xanthine+inosine levels in the blood) and, possibly, stimulation ofhaem degradation by haem oxygenase (markers total bilirubin and Fe in the blood). Diminishing content of free arachidonic acid in arterial blood can testify inhibition of cellular membranes phospholipides degradation by phospholipase A2 as a result of flocalin cardioprotection.

[Influence of flocalin on development of apoptosis and necrosis at anoxia-reoxygenation of culture rats neonatal cardiomyocytes].

The influence of the new cardioprotector flocalin was investigated on the culture of rat's neonatal cardiomyocytes during anoxia-reoxygenation modelling. The mechanisms of apoptosis and necrosis were investigated under influence of ATP-sensitive potassium (K(ATP)) channels activation and in conditions of blocking of the L-type calcium (VGCCs) channels. Flocalin was added in the culture medium in the dose 5 and 20 microM at 2 minutes before anoxia (30 minutes) and following reoxygenation (60 minutes). These doses are near to: the first dose means the opening of K(ATP) channels and the second one means the IC50 block of VGCCs. It is discovered that in dose 5 microM of flocalin drew the change of correlation of living, necrotizing and apoptizing cells drew side-shifting living. The number of live cells was almost the same like in control (experiments without anoxia-reoxygenation modelling). The opening of K(ATP) channels decreases necrosis in two times and fully prevented development of apoptosis which was induced anoxia-reoxygenation modelling. Flocalin depressed the apoptosis of neonatal cardiomyocytes so that he was on to 36% less than in control group (without anoxia-reoxygenation). But in the high dose (20 microM) that provokes not only K(ATP) channels opening but also IC50 block of VGCCs cardioprotection was not detected after modelling of anoxia-reoxygenation. The last can be investigation both enough strong activating of the potassium channels and by investigation of both factors are opening of potassium and inhibition of VGCCs channels and, accordingly, substantial diminishing of level of introcellular Ca2+ and violation of metabolic processes yet to anoxia-reoxygenation. Thus, small doses of flocalin, that induce moderate opening of K(ATP) channels significantly decrease the number of necrotic and apoptotic cells in culture of rat neonatal cardiomyocytes induced by anoxia-reoxygenation.

[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. Our studies suggest a protective effect of hydrogen sulfide donor on the functional state of the mitochondria. To elucidate of other the mechanisms of the protective action H2S we also investigated the effect of hydrogen sulfide donor on the mitochondrial swelling. It was found that NaHS in the range of concentration 10(-12) - 10(-4) mol/l influences the level of mitochondria swelling of the rats heart in the dose-dependent manner. It was also shown that when the concentration of Ca2+ 1 nmol/mg protein in the medium, under the action of hydrogen sulfide in the donor concentration range 10(-12) - 10(-8) mol/l, there was a moderate swelling of rats heart mitochondria. Under the action of NaHS at a concentration of 10(-9) mol/l it was observed swelling of the mitochondria, the maximum change in the level of which was 11%. Inhibitor of mitochondrial ATP-sensitive K+ channels (K(ATP) channels) 5-hydroxydecanoate (10(-4) mol/l) partially reduced the mitochondrial swelling in the presence of NaHS (10(-9) mol/l), which may indicate the activation of K(ATP) channels. Our studies point for possible involvement of mitochondrial K(ATP) channels in implementation of the mechanisms of H2S.

[Hydrogen sulfide inhibits Ca(2+)-induced mitochondrial permeability transition pore opening in spontaneously hypertensive rats].

In experiments in vivo and in vitro on the mitochondria isolated from the control and spontaneously hypertensive rats (SHR) 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, Ca2+. We found that NaHS (10(-4), 10(-5) and 5 10(-5) mol/l) influenced the mitochondrial swelling in a concentration-dependent manner in control and spontaneously hypertensive rats. The H2S donor NaHS used in physiological concentrations (10(-6), 10(-5) and 5 10(-5) mol/l) exerted the inhibiting effect on the Ca(2+)-induced mPTP opening in control hearts (corresponding values of such effect were 31, 76, and 100%, respectively), while in spontaneously hypertensive rats hearts the protector effect of NaHS was observed only at its concentration of 10(-5) - 10(-4) mol/l. In experiments in vivo, single intraperitoneal injections of L-cysteine (10(-3) mol/kg) resulted in a decrease in the sensitivity of mPTP to it's inductor Ca2+ in control rats and SHR. In experiments in vivo in which we used a specific blocker of cystathionine-gamma-lyase, propargylglycine (10(-4) mol/kg), with the further injections of L-cysteine we observed a decrease in the threshold Ca2+ concentration (that induce the mitochondrial swelling) by three orders of magnitude in SHR, but in control rats did not effect of L-cysteine. Thus, both endogenous and exogenous hydrogen sulfide inhibits Ca(2+)-induced mitochondrial permeability transition pore opening, indicating its protective effect on pore formation in spontaneously hypertensive rats hearts. Therefore, our studies are indicative of the involvement of H2S in modulation of changes in the permeability of mitochondrial membranes, which can be an important regulatory factor in the development of cardiovascular diseases.

[The influence of activation of the ATP-sensitive potassium channels by flocalin on the function of the cardiovascular system].

In experiments on the anaesthetized dogs the influence of a new fluorine-containing opener of ATP-sensitive potassium (K(ATP)) channels flocalin on the cardiohemodynamic of great animals in vivo was studied. Flocalin introduced intravenously in doses 0.01 - 1.5 mgs/kg. It is shown that it reduces in dose-dependent manner a system arterial pressure, perfusion pressure in coronary artery and general peripheral resistance of vessels with maximal effects on 56.8 +/- 2.7, 22.4 +/- 4.7 and 47.2% +/- 6.5% accordingly at most dose 1.5 mgs/kg. Flocalin causes development of cardiodepressive reactions in heart, that is exhibited in dose-dependent the decrease of pressure in the left ventricle, speed of growth (dP/dt(max)) and reduction (dP/dt(min)) in it's of pressure with maximal effects on 37.1 +/- 5.1, 51.2 +/- 9.4 and 55.6% +/- 6.9% accordingly at introduction of most dose of flocalin. Diminish of the cardiac out put and heart rate with a maximal effects on 23.1% +/-12.7% and 19.2% +/- 1.7% accordingly at a dose 1.0 mgs/kg was shown. It should be noted that considerable reduction of heart rate and general peripheral resistance of vessels takes place only at the large doses of flocalin - 1 and 1.5 mgs/kg. Thus, it is shown that activation of K(ATP) channels by flocalin causes the dose-dependent decrease of pressure in the system of circulation of blood and contraction activity of myocardium.

[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. We found that concentration-dependent inhibitory effects (10(-7) to 10(-4) M) of flocalin (with IC50 = 50 microM) and tioflocalin (with IC50 = 2,7 microM) on Ca(2+)-induced mitochondrial swelling (MPTP opening) in the heart characterized more powerful cardioprotective action of the latter. It was shown that the administration of these compounds in experiments in vivo decreased the sensitivity of the MPTP opening to Ca2+. Thus, under physiological conditions the activators K(ATP)-channels probably provide the membrane-stabilizing effects, thereby effectively increasing the organelles resistance to Ca2+, an inductor of MPTP. The results obtained allowed to characterize the role of the compound studied as cardioprotectors and regulators of the MPTP formation in the heart, indicated their anti-ischemic and anti-apoptotic effects that can be used in order to correct the mitochondrial dysfunction under pathological conditions of the cardiovascular system.

[Increase in the sensitivity of the mitochondrial permeability transition pore opening to Ca2+ in heart of spontaneous hypertensive rat].

In experiments vitro on the mitochondria isolated from adult and spontaneous hypertensive rat hearts, we studied the sensitivity of the mitochondrial permeability transition pore (mPTP) opening to its natural inductor, Ca2+. We observed an increase in the sensitivity of mPTP opening to Ca2+ in the heart of spontaneous hypertensive rats because of a decrease in the threshold concentration of this ion required for organelles swelling by two orders of magnitude. It was shown that the classical inhibitor mPTP cyclosporin A (10(-5) mol/L) partially (54%) inhibited of mPTP opening in the heart of these animals, indicating that the presence in the heart of these animals of cyclosporin A-insensitive component of the mPTP. The results of our observations give reason to conclude that the hypertensive state of the organism is associated with mitochondrial dysfunction, which is characterized, in particular, by an increased sensitivity mPTP to Ca2+, eliciting a widespread tissue damage and diseases of the cardiovascular system, especially hypertension.

[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. At 10(-10) mol/l NaHS, the maximal values of the mitochondrial swelling observed in both adult and old hearts were 11 and 15 ,%, respectively. A specific inhibitor of KATP channels, 5-hydroxydecanoate (5-HD; 10(-4) mol/l) decreased the mitochondrial swelling in the presence of NaHS (10)-10) mol/l), which can be indicative of the contribution of these channels to the calcium-independent conductance of the mitochondrial membranes in the rat hearts. The H2S donor NaHS used in physiological concentrations (10(-6), 10(-5) and 5 10(-5) mol/l) exerted the inhibiting effect on the Ca(2+)-induced mPTP opening in adult hearts (corresponding values of such effect were 31, 76, and 77%, respectively), while in old hearts the protector effect of NaHS was observed only at its concentration of 10(-5) mol/l. Therefore, the donor of H2S used in the tested concentrations (10(-12) to 10(-4) mol/l) exerted ambiguous effect on the mitochondrial swelling: low concentrations of NaHS (10(-12) to 10(-8) mol/l) increased the mitochondrial swelling, while its physiological concentrations (10(-6) to 5 10(-5) mol/l) exerted the protective effect on Ca(2+)-induced mitochondrial swelling in adult and old hearts. Pre-incubation of isolated mitochondria with 5-HD (10(-4) mol/l) resulted in a decrease in the protective effect evoked by NaHS (10(-5) mol/l) on Ca(2+)-induced mPTP opening, which is indicative of the possible involvement of mitochondrial KATP-channels in the H2S-dependent inhibition of mPTP formation in both adult and old rat hearts. In experiments in vivo, single intraperitoneal injections of both NaHS (10(4) mol/kg) and L-cysteine ((10(-3) mol/kg) resulted in a decrease in the sensitivity of mPTP to its inductor Ca(2+) in adult and old rat hearts. The action of L-cysteine, as compared with that of NaHS, was more effective in prevention of Ca(2+)-induced mitochondrial swelling. We observed a rise in Ca(2+) concentration by one order of magnitude, which evoked the mitochondrial swelling in adult and old hearts. In experiments in vivo in which we used a specific blocker ofcystathionine-g-lyase, propargylglycine (10(-4) mol/kg) that is involved in the synthesis of H2S, we observed an increase in the sensitivity of mPTP opening in old hearts because of a decrease in the threshold Ca(2+) concentration required for mitochondrial swelling by two orders of magnitude. We demonstrate the involvement of endogenous H2S in the control of mPTP formation in adult and old hearts. Our studies are indicative of the involvement of H2S in modulation of changes in the permeability of mitochondrial membranes, which can be an important regulatory factor in the development of cardiovascular diseases.

[Increased expression of voltage-dependent anion channel and adenine nucleotide translocase and the sensitivity of calcium-induced mitochondrial permeability transition opening pore in the old rat heart].

We investigated mRNA and protein expression of voltage-dependent anion channel (VDAC), mRNA adenine nucleotide translocase (ANT) as well as the sensitivity of the mitochondrial permeability transition pore opening (MPTP) to Ca2+ in the adult and old rat heart. It was shown that in the old rats hearts VDAC mRNA expression increased by 1.7 (p < 0.05) times and mRNA ANT expression increased by 1.8 (p < 0.05) times in comparison with adult animals. The Western Blot analysis showed that the level of VDAC protein expression in the old rat hearts also significantly increased compared with adult animals. In the hearts of old rats, the sensitivity of MPTP opening to calcium (10(-7)-10(-4) mol/l) determined by mitochondria swelling, increased two-fold (p < 0.05). Therefore, an increased VDAC and ANT expression, as the main structural functional components of the MPTP, and an increased sensitivity of MPTP opening to Ca2+ caused an increase in the permeability of mitochondrial membranes in aging. Each of these factors may contribute to alterations in mitochondrial barrier properties and lead to mitochondrial dysfunction.

[Cardioprotective action of coenzyme Q in conditions of its endogenous synthesis activation in cardiac ischemia-reperfusion in old rats].

The changes of functional state isolated by Lanhendorf old rat hearts with low content of ubiqinone--coenzyme Q (CoQ) under activation of it endogenous synthesis through administration of precursors--4-hydroxybenzoic acid, methionine and modulator vitamin E were studied. The activation of ubiqinone biosynthesis contribute to cardioprotective effect due to reduce the degree of the ischemia-reperfusion injury in old rat heart, namely the restoration of myocardial contractile function and coronary flow as well as decrease the end diastolic pressure and oxygen cost of the heart compared with control group of the animals during ischemia-reperfusion. Thus the results allow to conclude that the activation of KoQ biosynthesis under administration of it precursors has protective effect in the development of the heart postreperfusion damages in aging.

[Expression of UCP3 and the sensitivity of mitochondrial permeability transition pore opening to Ca2+ in old rat heart under activation of biosynthesis of coenzyme Q].

The expression of mitochondrial uncoupling protein 3 (UCP3), as well as the sensitivity of mitochondrial permeability transition pore opening (MPTP) to Ca2+ (10(-4) mol/l) in old rat heart under activation in vivo of ubiquinone synthesis--coenzyme Q, (CoQ) via administration of the precursors (4-hydroxybenzoic acid, aminoacid methionine and modulator vitamin E) were studied. It was shown that the expression level of UCP3 decreased by 63% in old rats compared to adult rats and this was accompanied by an increased sensitivity of the MPT to calcium. Under activation of endogenous synthesis of CoQ it was observed almost complete restoration of UCP3 expression in old rat heart and a decrease in the sensitivity of the MPTP opening to Ca2+. In mitochondria from old rat hearts we noted an increased content of the superoxide (O2) and hydroxyl (OH) radicals and of the stable metabolite of active oxygen species hydrogen peroxide (H2O2), as compared to those in adult animals. Following activation of endogenous synthesis of CoQ in old rat heart mitochondria it was observed a decreased content of H2O2, and the tendency for decreasing the levels of the radicals O2 and MOH. The results obtained allowed to conclude that the CoQ-dependent restoration of the UCP3 levels in old rat heart and antioxidant/cardioprotective effects of CoQ related to the MPTP opening inhibition can reduce the oxidative stress and thus prevent the manifestation of mitochondrial dysfunction in aging heart. We suggest that UCP3 is not involved in the increase of the passive H-conductance through the inner mitochondrial membrane in the aging heart, and that CoQ as a factor of respiratory chain could be an important endogenous regulator of the uncoupling proteins, in particular UCP3, in the heart.

[In vivo effect of precursors of ubiquinone biosynthesis on sensitivity of mitochondrial permeability transition pore in the heart of old rats].

This research work is devoted to study of the sensitivity of mitochondrial permeability transition pore (MPTP) opening to its inductors--ions Ca2+ (10(-4) mol/l) and oxidant phenylarsine oxide (10(-4) mol/l) and content of ubiquinone (coenzyme Q, CoQ) and vitamin E in heart mitochondria of adult, old (control) and old rats under administration of precursors an modulator of CoQ biosynthesis--4-hydroxybenzoic acid, methionine and modulator of CoQ biosynthesis, namely vitamin E. The results of our research demonstrate that administration of complex of biologically active substances, which are precursors and modulators of CoQ biosynthesis, leads to decrease in the sensitivity of MPTP opening to its inductors and increase of CoQ and vitamin E content in old rats heart mitochondria. Therefore the results obtained lead to a conclusion that increase of CoQ content due to administration of precursors and modulator of its biosynthesis is an effective way in the inhibition of MPTP opening. This approach as well as application of CoQ-containing medicals may be used for correction of mitochondrial dysfunction under various pathologies of cardiovascular system and in aging.

[Aging-related increase of sensitivity of the mitochondrial permeability transition pore to inductors in the rat heart]. / Starinnia pidvyshchyie chutlyvist' do induktoriv mitokhondrial'noï pory v sertsi shchuriv.

An age-related increase in the sensitivity of the mitochondrial permeability transition pore (MPTP) to inductors of it's opening, Ca2+ ions and phenylarsineoxide (PAO) was studied in experiments in vitro on isolated heart mitochondria of adult and old rats. Two indices were measured spectrophotometrically (lambda = 520 nm) by a decrease in an optical density (OD), resulting from mitochondrial swelling and a release of mitochondrial unidentified substances (mitochondrial factor, MF) registered also spectrophotometrically in a range of waves lambda = 230-260 nm. Dose-dependent effect of Ca2+ (10(-7)-10(-4) mol/l) and PAO (10(-8)-10(-4) mol/l) on swelling of the mitochondria were observed in samples from both adult and old rats. Swelling of the mitochondria from the heart of old rats induced by application of the above inductors was more intensive than the respective effect in samples from adult rats. In samples from the heart of both adult and old rats Ca2+ ions within the tested concentration range (10(-7)-10(-4) mol/l) evoked the release of MF in a dose-dependent manner. Mitochondria from the heart of old rats were found to be capable of releasing some amounts of MF in the absence of the MPTP inductors PAO. When this inductor was applied in a 10(-9) to 10(-4) mol/l concentration range, isolated mitochondria from the heart of old rats released unidentified substances with the absorption peaks at two wavelength, lambda = 230 nm and lambda = 240-245 nm. The former peak was found to be Cyclosporin A-insensitive, while the latter peak could be practically completely inhibited by this antibiotic. The concentrations of tested solutions (10(-7) mol/l CaCl2 and 10(-9) mol/l PAO), at which the release of the factor from the mitochondria of the old rat heart was observed, were significantly lower than those in adult rats. Our experimental data show that mitochondria isolated from the heart tissue of old rats demonstrate significantly higher sensitivity to inductors of MPTP-opening, Ca(2+)-overload and PAO as compared to that typical of adult animals. A higher sensitivity of MPTP-opening in the heart of old rats was accompanied by a higher basal level of expression of mRNA of the bax gene, as compared to that found in adult animals. The expression of the bcl-2 gene showed no age group-related differences. It can be supposed that a proapoptotic agent, the Bax protein, is related to an increase in the sensitivity of the MPTP (in particular to that manifested in the processes of pore formation) in the course of aging. Antioxidants, melathonin and trolox, when applied in 10(-5) mol/l concentration, presented to a certain extent opening of the MPTP-induced by 10(-5) mol/l PAO in samples from adult and old rats. These findings can be used for correction of increased sensitivity of the MPTP to different inductors, which is typical of old rats. We conclude that physiological aging is accompanied by the mitochondrial dysfunction. The MF-released capability of the mitochondria from heart tissue of old rats observed both in the presence and absence of MPTP-opening inductors (probably related to a higher sensitivity of MPTP-opening) is one of the manifestation of such dysfunction.

[Sensitivity of phenylarsineoxide-induced mitochondrial permeability transition pore opening in the heart of old rats during intermittent hypoxic training]. / Chutlyvist' fenilarsynoksydindukovanoho vidkryttia mitokhondrial'noï pory v sertsi starykh shchuriv za umov vplyvu na nykh interval'nykh hipoksychnykh trenuvan'.

We studied the sensitivity of mitochondrial permeability transition pore (MPTP) opening to its inductor-phenylarsineoxide (PAO) in adult (6 months), old rat heart (24 months) and in old rat heart under conditions of intermittent hypoxic training (IHT). We defined the sensitivity of MPTP opening on two parameters: the alterations in mitochondrial swelling and the release ofmitochondrial substances (mitochondrial factor). It was shown that mitochondria of old rat heart are more sensitive to PAO which caused opening of cyclosporin-sensitive MPTP and MPTP-dependent factor release, in comparison with those of adult rat heart mitochondria. One of the causes of increased sensitivity of MPTP opening to PAO is development of an oxidative stress with age that was accompanied by increase of an active metabolite of oxygen IHT on PAO-induced MPTP-opening and MPTP-dependent factor release from old rat heart mitochondria. IHT also reduced the content of H2O2 and *OH in old rat hearts. IHT can be used as protective procedure preventing MPTP opening in aging and, probably, in a numerous chronic pathological states of organism under oxidative stress.

[Release of unidentified substances of mitochondrial origin--evidence of mitochondrial permeability transition pore opening in the heart mitochondria of rats ]. / Vyvil'nennia neidentifikovanykh rechovyn mitokhondrial'noho pokhodzhennia--pokaznyk vidkryttia mitokhondrial'noï pory sertsia shchuriv.

In experiments in vitro on isolated heart mitochondria of rats, an activation of mitochondrial permeability transition pore (PTP) was induced by either modelling an oxidative stress with PTP-inductor phenylarsine oxide (PAO) or by calcium overload (CaCl2). PTP-opening was determined spectrophotometrically (lambda = 520 nm) by a decrease in an optical density (OD), resulting from mitochondrial swelling. We also observed a release of mitochondrial unidentified substances (mitochondrial factor, MF) registered spectrophotometrically in a range of waves lambda = 230-260 nm. Both correlation between mitochondrial swelling and a release of the mitochondrial factor have been found in experiments with PAO at concentrations 10(-7)-10(-4) mol/l, and in those with CaCl2 at concentrations 10(-6)-10(-4) mol/l. The classical inhibitor of mitochondrial PTP cyclosporin A (Cs A, 10(-5) mol/l) inhibited mitochondrial swelling and a release of that factor completely. Our experimental data give evidence for mitochondrial origin of the factor and its release following PTP-opening by PTP-inductors--PAO and CaCl2. Mitochondrial swelling that accompanied the factor's release might contribute to PTP-opening and be useful in defining the mitochondrial sensitivity either with inductors or inhibitors of mitochondrial PTP in different tissues under normal and pathological states of organism.

[Effect of inductors and inhibitors of the mitochondrial permeability transition pore on its opening and release of unidentified mitochondrial factor]. / Vplyv induktoriv ta inhibitoriv mitokhondrial'noï pory na ïï utvorennia ta na vyvil'nennia neidentyfikovanoho mitokhondrial'noho faktora.

The release of an unidentified substance (factor) induced by sulfhydryl group (SH) modifier and mitochondrial permeability transition pore (MPT) inductor phenylarsine oxide (PAO) has been found in vitro on isolated guinea-pig and rat heart mitochondria. The factor was also released at oxidative stress. The factor release induced by PAO was inhibited by cyclosporin A (CsA), the MPT inhibitor. Protective actions of antioxidants melatonin and trolox in vitro and in vivo, as well as dithiothreitol (DTT) and diethylmaleat (DEM) were studied. The influences of nitric oxide (NO) donor, sodium nitroprusside (SNP) on the mitochondrial factor release were also studied. We have shown the participation of this agent in the regulation of factor formation after inhibition of NO-synthase activity (NOS) by aminoguanidine. The data were obtained about MPT-opening after Ca2+ loading and under the influence of the MPT inductor PAO, inhibited by CsA. The results obtained on isolated mitochondria are in a good agreement with the those on the isolated guinea-pig heart after myocardial ischemia-reperfusion. It was concluded that mitochondria are essential for the factor formation and its release under ischemia-reperfusion of the myocardium.

[Content and transportation of Ca(2+) to hepatocytes and lipid content of liver cell membrane structure in experimental diabetes in the rat]. / Vmist i transportuvannia Ca(2+) v hepatotsytakh ta lipidnyi sklad membrannykh struktur pechinky za eksperymental'noho tsukrovoho diabetu v shchuriv.

It is proved that at experimental diabetes the calcium content in hepatocytes is disturbed. This disorder is mostly shown in increase of calcium content in hepatocytes and in decrease of accumulation of these ions in mitochondrias. One of the possible reasons of changes at this pathology is the change of lipid content of hepatocytes, mitochondrias and microsomes. It is proved that the in vitro model systems Ca ions inhibits the synthesis of 25-hydroxyvitamin D3 by hepatocytes.