[Induction of nitrosative stress in mitochondria of rats hearts in experimental ischemia-reperfusion of the brain and its correction by ecdysterone]

On the model of focal ischemia-reperfusion of the brain investigated the induction of nitrosative stress in mitochondria of rats hearts and possible mechanisms of protective action of ecdysterone. It is shown that focal ischemia-reperfusion of the brain induced in myocardial mitochondria the activation of constitutive and inducible de novo synthesis of NO by oxidation of L-arginine and not oxidative synthesis of NO through the recovery of oxidized stable metabolites of NO. Strong evidence of induction of nitrosative stress in heart mitochondria by focal ischemia-reperfusion of the brain, was a significant increase in mitochondrial pool of nitrate- and nitrite-anions and pools of nitrosothiols, that is proof of the formation and decay of peroxynitrite--a key marker of nitrosative stress. Also was observed increase in heart mitochondria by focal ischemia-reperfusion of the brain, content key regulator of de novo synthesis of NO-hydrogen sulfide and activity of inducible arginase II and, as a result, the pool of carbamide, which is also a regulator of the synthesis of NO. Previous introduction for animals herbal extract Serratsula coronata, enriched ecdysterone, reduces induction nitrosative stress in mitochondria of rats hearts under conditions of focal ischemia-reperfusion of the brain.

[Propargylglycine restores endothelium-dependent relaxation of aortic smooth muscles in old rats]

In the study we investigated the effect of blockade cystathionine-gamma -lyase (CSE), an enzyme of hydrogen sulfide (H2S) (de novo) synthesis on the endothelium-dependent relaxation of aortic smooth muscle (SM) in old rats. It has been shown that an inhibition of CSE by propargylglycine (PAG) results in restoration of a decreased ACh-induced relaxation of aorta in old rats. This effect of PAG was removed by blocking nitric oxide (NO) synthesis in the endothelial cells. Age-related changes in the levels of H2S, NO2- and enzyme activity of the constitutive synthesis of NO (cNOS) in the heart, were determined. It has been shown that PAG introduction elevates a decreased levels of HzS, NO2- and stimulates the suppressed activity of cNOS in old rats. These results suggest that PAG activates alternative ways of H2S synthesis and stimulates the constitutive synthesis of NO. These actions of PAG restore endothelial function in old rats.

[Induction of oxidative stress in heart mitochondria in brain focal ischemia-reperfusion and protective effect of ecdysterone]

Based on the fact that the acute phase of ischemic stroke is accompanied by the development of heart damage, manifestations of which are oxidative stress, morphological changes in the myocardium, in the model of brain focal ischemia-reperfusion, we investigated the oxidative stress in rat heart mitochondria and possible mechanisms of cardioprotective effect of ecdysterone. Under the conditions of brain focal ischemia-reperfusion, there is an increase rate of the generation of reactive oxygen species: superoxide (*O2-) and hydroxyl radicals (*OH), pools of stable hydrogen peroxide (H2O2), accumulate products of lipid peroxidation (diene conjugates and malonic dialdehyde), as a result of activation xanthine oxidase (marker uric acid), lipooxygenase (marker leukotriene C4) and cyclooxygenase (marker tromboksane B2) ways of *O2-(generating). In animals that received ecdysterone for 18 days, under conditions of brain focal ischemia-reperfusion, the rate of reactive oxygen species generation and the pools of lipid peroxidation products were decreased, and the survival of animals was increased. The obtained results support the development of oxidative stress in heart mitochondria of rats, powerful antiradical properties ofecdysterone, its cardioprotective effect, in conditions of brain focal ischemia-reperfusion.

[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.

[Magnetic-laser influence on the system of nitric oxide and contractile activity of smooth muscles of rat aorta under hypertension]

The study was conducted on three groups of rats: Group I included Wistar rats with normal blood pressure (first control group); group II - rats with genetically determined hypertension (second control group); group Ill - rats with genetically determined hypertension under the influence ofmagnetic-laser power (study group). For the low-intensively magnetic-laser influence (MLI) we have used device MIT-MT, Ukraine, which was designed for the treatment of low-frequency magnetic field using optical flow blue and red ranges of spectrum. The MLI duration was 15 minutes for the blue range, and 25 minutes for the red one. Biochemical studies included the determination of the activity of isoenzymes of NO-synthase: constitutive (cNOS) and inducible (iNOS), the content of free hemoglobin, stable metabolites of NO, namely nitrite - (NO2(-)) and nitrate - (NO3(-)) anions, resistance to acid hemolysis of red blood cells. The contractile activity of smooth muscles of the aorta was measured. We found that magnetic-laser exposure of rats with genetically determined hypertension in the red (630 nm) and blue (470 nm wavelength) optical range even after a single session leads to an increased synthesis of nitric oxide in the blood plasma. Our data sindicate that the most effective in the intensification of endogenous nitric oxide (increase of NO2(-) and reduction of NO3(-)) and endothelium-dependent responses of aorta in rats with genetically determined hypertension was a ten-day course of the magnetic-laser exposure in the optical flow of the blue spectral range. Also, after 10 sessions of magnetic-laser exposure in rats from the above specified spectrum a stabilization of erythrocyte membranes was observed.

[Arginase-nitric oxide synthase system changes due to adaptation to swimming in adult and aged rat hearts]

We tested the physiological indices of adult rat heart beat for the adaptation to prolonged physical exercise (swimming). It was shown that the stimulation of NO-production in the heart mitochondria of trained adult rats improves both systolic and diastolic heart function. In adult rats trained by swimming the activity of both de novo and salvage enzymes of nitric oxide synthesis studied (iNOS, cNOS, nitratreductase) were increased in heart mitochondria, whereas in the old rats only the activity of oxidative de novo enzymes. Training reduced the nitrate pools only in the mitochondria from adult rats and the urea pools in mitochondria from old rats. Intramitochondrial nitrite pools were unchanged. In adult rats, mitochondrial H2O2 pools increased after training, whereas in the old rats they were reduced, the level of uric acid (a marker ofxanthinoxydase activity) in ageing rats after training period was declined. Swimming training resulted in a significant increase in the value of "oxygenation index" in mitochondria of adult rats and decreased the activity of mitochondrial arginase II. The results suggest that swimming is one of the methods of physical load stimulates NO production in the mitochondria of adult and old rats and therefore could be considered as an effective non-pharmacological tool for correction of mitochondrial dysfunction in adults and aging heart.

[Reactive nitrogen and oxygen species metabolism in rat heart mitochondria upon administration of NO donor in vivo]

Some aspects of reactive nitrogen and oxygen species (RNS and ROS) metabolism in rat heart mitochondria under administration of different doses of nitroglycerine (NG) in vivo are discussed. It is shown that NG administration results in a dose-dependent increase in Ca2+-uptake in mitochondria, due to the dose-dependent inhibition of mitochondrial permeability transition pore (MPTP) in vivo and the activation of Ca2+-dependent mitochondrial NOS. It was shown that NOS activity increases in accord with the increase of Ca2+-uptake in mitochondria. The dose-dependent activation of nitratreductase is observed. However, nitrite production decreases dose-dependently, according to the change of NO2-/NO3- ratio on behalf of NO3-, the end product of NO transformations. The relation between nitrosylation of mitochondrial proteins with the nitrosothiols formation and nitrate production also changes towards NO3-, which shows the activation of oxidation reactions in heart mitochondria after NG administration. Accordingly, dose-dependent increase in lipid peroxidation (LP) products is shown, the hallmark of the membrane damage in mitochondria. It is established that the cause of oxidative stress, besides the dose-dependent increase in ROS production (hydroperoxide, superoxide and hydroxyl-radical), lies in the increase of free iron content, derived from the oxidation of mitochondrial iron-containing proteins. The iron interaction with hydroperoxide following Fenton reaction as well as free-radical decomposition ofperoxynitrite, derived from NO3- are the possible cause of manifold increase in ROS as well as LP production, and RNS oxidation to NO3-. Thus, NO-dependent MPTP blockage, due to NO synthesis in mitochondria in vivo, results in the activation of both constituents of NO-cycle: NOS-dependent, due to Ca2+-dependent activation of mitochondrial NOS, and nitrate-reductase-dependent, due to the increase in NO3- formation. However, increase in ROS production, augmented by the iron release, leads to the oxidative stress and the shift of RNS metabolism towards NO3- formation, in spite of the activation of nitrate-reductase-dependent pathway of NO-cycle. It is shown that reversible MPTP opening in vitro diminishes ROS production, whereas MPTP blockage by cyclosporine A restores the ROS formation to control level. Thus, MPTP-dependent inhibition of ROS overproduction both in vitro and in vivo, shows the importance of MPTP in the regulation of ROS and RNS metabolism in mitochondria.

[The changes of metabolism in myocardium at ischemia-reperfusion and activating of the ATP-sensitive potassium channels]

In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min) it was investigated the changes of biochemical processes in the different areas of heart (intact, risk and necrotic zone) during 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 cardioprotective mechanisms of flocalin action at ischemia-reperfusion conditions: the preservation of sufficient levels of de novo (by cNOS) NO synthesis, an inhibition of de novo (by iNOS) and salvage (by NADH-dependent nitratreductase) NO synthesis, an inhibition of L-arginine degradation by arginase, an inhibition of oxidizing metabolism due to limitation of ROS and RNS generation, inhibition of free arachidonic acid and eicosanoids synthesis, inhibition of ATP and GTP degradations and, possibly, stimulation of protective haem degradation. These changes may prevent formation of toxic peroxynitrite and suggest the possibility of participating in flocalin-mediated cardioprotective effects of warning a mitochondrial permeability transition pore (MPTP) opening and inhibition of apoptosis and/or necrosis of cardiomyocytes induced by it.

[Nitric oxide synthesis during different stages of competition period in well-trained athletes]

In the study 26 trained male and female sportsmen aged 18-20 years old have been investigated. The sex differences in the degree of the nitric oxide synthesis in various stages of their training and competitive activities were shown. In female sportsmen, at the time of maximal functional capacity and adaptation (beginning of the competition period), a multi-path nonoxidizing arginine metabolism by arginase was prevailed over the oxidative degradation of L-arginine by cNOS. In females, during dezadaptation period (in the middle and the end of competition), the required level of NO synthesis is maintained mainly by non-oxidative resynthesis of nitric oxide from its stable metabolites. In males, however, the level of NO synthesis is maintained mainly by an increase in oxidative degradation of L-arginine with the gradual change in activity of different isoforms of NOS (cNOS as well as iNOS).

[Characteristics of arginine metabolism and nitric oxide synthesis in young people during adaptation to physical load in training and competition periods]

A survey of 29 trained and untrained youths in the age of 18-20 years was carried out. It is shown that the optimal level of adaptation of the body to prolonged and intensive physical activity is provided by multi-dominance nonoxidizing arginase metabolism and its oxidative metabolism by constitutively calcium dependent NO-synthase (eNOS and nNOS). Nonoxidizing arginase metabolism results in formation of several important low-molecular bioregulators and antioxidants (urea, polyamines, GABA). Significant reduction of functionality of the trained body at the end of the competitive period and consequently disadaptation correlates with Ca(2+)-independent NO synthesis which does not compensate the organism needs in NO.

[Changes of vascular reactivity and reactive oxygen species in conditions of varying duration of permanent stay in the alienation zone in mice]

Peculiarities of changes in the vascular reactivity and in the content of reactive forms of oxygen and stable metabolites of nitric oxide (NO) were studied in the aorta preparations of C57BL/6 and BALB/c mice of the two age groups (6 and 18 mo.), which were born and permanently kept in the Chernobyl alienation zone. The results obtained showed a disturbance of acetylcholine-induced endothelium-dependent reactions of relaxation of smooth muscles of the thoracic aorta. A lower level of NO synthesis and lower level of oxidative arginase metabolism of arginine corresponded to a higher degree of damage of endothelium-dependent reactions of relaxation of the thoracic aorta smooth muscles. A decrease of NO synthesis in conditions of permanent effects of low doses of radiation was conditioned by an increase of generation of reactive forms of oxygen, namely, superoxide and hydroxyl radicals, which might be formed in mitochondria. In conditions of permanent effects of low doses of radiation a lesser level of protein nitrosothilation, same as lesser one of generation of OH-radical, corresponded to a higher level of damage of endothelium-dependent reactions.

[The role of mitochondria in NO-dependent regulation of Na+, K+ -ATP activity in the rat aorta]

In experiments in vivo we studied the interaction between two ion-transporting mechanisms of cardiovascular system--Na+, K+ -ATPase of rat aorta and Ca2+ -uptake system of mitochondria in short-term response to different doses of NO donor, nitroglycerine (NG). The activity of the Na+, K+ -ATPase was determined in rat aorta, and mitochondrial uptake of Ca2+ was studied in rat heart mitochondria assuming that metabolism induced by NO in cardiac mitochondria is similar to that in rat aortic mitochondria. The data show a coordinated dose-dependent action of NG on Na+, K+ -ATPase activity as well as Ca2+ -uptake in mitochondria. An activation of Na+, K+ -ATPase by low dose of NG (0.25 mg/kg body weight) is accompanied by the activation of Ca2+ -uptake in mitochondria as a result of inhibition of permeability transition pore. However, further increase of the dose of the drug leads to reciprocal changes of studied parameters: the decrease in Na+ -pump activity below the control level and the increase of Ca2+ -uptake in mitochondria with a peak at 1.0 mg/kg NG, which takes place in parallel with the dramatic rise in the level of ROS and RNS together with their toxic products, nitrosothiols (NT) and free iron (Fe2+) content in mitochondria. Strong correlation between Ca2+ -uptake and Fe2+ -release, Fe2+ -release and OH-radical formation, the rise in OH-radical level and the decrease of that of H2O2 and mitochondrial NT together with the inhibition of Na+, K+ -ATPase favor a hypothesis that oxidative stress in rat aorta is of mitochondrial origin due to an enhanced uptake of Ca2+ into mitochondrial matrix, Fe2+ deliverance and manifold increase in OH-radical formation from decomposition of hydroperoxide in Haber-Weiss reaction and the decomposition of mitochondrial NT via formation of peroxynitrite, both catalysed by Fe2+, with subsequent release of *OH-radical. Effective abolition of Na+, K+ -ATPase inhibition by potent antioxidant melatonine gives the evidence of the oxidative nature of Na+, K+ -ATPase inhibition by nitric oxide in rat aorta.

[Vascular reactivity and metabolism of the reactive oxygen species and nitrogen in effects of low doses of radiation]

The disturbance of endothelium-dependent and endothelium-independent vascular reactions of relaxation was registered in the preparations of aorta of radiosensitive BALB/c mice, exposed to chronic external gamma-irradiation (cumulative dose of 0.43 Sv). Low doses of radiation induced an intensive hydrolysis of membrane phospholipids by phospholipase A2, displayed by an increase in the level of eukosanoisds--LTC4 and TxB2, formed under effects of lipid oxidases (lipoxygenase and cyclooxygenase) at the same time with O2 generation. High doses of O2- can also be formed under the effect of low doses of radiation along xanthine oxidase pathway simultaneously with uric acid. In these conditions *OH-radical is formed not only at the expense of water radiolysis, which is observed under the effect of high doses, as well as along the two--NO-dependent and NO-independent--pathways. Significant increase in the content of lipid peroxidation products--dienic conjugates and valonic dialdehyde--in the organs of cardiovascular system is a confirmation of active generation of *OH and *NO2 under the effect of low doses of radiation. The latter induce significant changes in the pools of NO stable metabolites, which can cause disturbance of NO-dependent physiological functions of both heart and aorta. Significant decrease in the levels of nitrite and nitrozothiols in these conditions may result in an oxidative stress. In increased simultaneous generation of *O2- and NO they may bind and thus form a toxic substance peroxynitrite. This notion can be confirmed by the low doses of nitrite, which are formed spontaneously in the presence of molecular oxygen against the background of increased or control levels of nitrate, which is formed mainly at the degradation of peroxynitrite, i.e. at high levels of superoxide anion.

[Cardioprotective effects of activation of ATP-sensitive potassium channels in experiments in vivo: influence on blood biochemical parameters following ischemia-reperfusion of the myocardium]

In experiments on the anaesthetized dogs with modeling of experimental ischemia (90 min) and reperfusion (180 min), the participation of biochemical processes in the cardioprotective effect of the preischemic activation of ATP-sensitive potassium (KATP) channels caused by intravenous introduction of flokalin, a new fluorine-containing opener of these channels was shown. Flokalin was introduced in a dose 0.1 mg/kg of animal body weight which practically did not change the parameters of hemodynamic in normoxia. Thus, the experiments investigating the influence offlokalin on changes of biochemical parameters of arterial blood during ischemia-reperfusion of myocardium showed certain features of ischemia-reperfusion syndrome development during stimulation of K(ATP) channels. The analysis of biochemical parameters of blood showed that flokalin suppressed free radical reactions and had antioxidant properties: reduced quantity of H2O2 and NO3- (the last can interpreted as a reduction in peroxynitrites formation), prevented the decline of catalase and superoxide dismutase activity. Practically constant content of low-molecular nitrosothiols in blood during all duration of experiment and increase of NO2-level during reperfusion may indicate on intact functions of the NO system and protective influence of flokalin during ischemia-reperfusion of myocardium. Practically unchanged content of inorganic phosphorus and uric acid in blood during ischemia- reperfusion under conditions of preischemic introduction of flokalin indicates the prevention of ATP degradation and fomation of both superoxide anion by xanthinoxidase and peroxynitrite by it interaction with nitric oxide. All mentioned properties of flokalin related to the changes of biochemical parameters of arterial blood, together with the changes of parameters of hemodynamics, result in diminishment of infarct size of myocardium after ischemia-reperfusion by 37% versus control experiments. K(ATP) channels, flokalin, ischemia-reperfusion, free radikaly, NO system.

[Oxidative stress in the cardiovascular system of rats with chronic deficiency of cerebral dopamine]

The physiological significance of cardiac mitochondrial reactive oxygen species (ROS) regulation is unknown. In the current study, mitochondrial ROS (O2- and OH) generation, stable H2O2 and lipids peroxidation marker (malonic dialdehyde, MDA) pools, as well as pools of potent antioxidants--urea and uric acid--were determined in rat heart, miocardial mitochondria and in blood plasma and erytrocytes at low (44%) and high (96%) levels of cerebral dopamine-synthesis neurons destruction (by 6-hydroxidopamine treatment). In the untreated rats, ROS generation, H2O2 and MDA levels were low but in rats with chronic (3-4 month) deficiency of cerebral dopamine synthesis by nigro-striatal dopaminergic system, ROS generation and lipids peroxidation were progressively increased. Dopamine deficiency can improve mitochondrial efficiency of oxidative phosphorylation due to oxidative stress.

[Nitric oxide synthesis during long-term adaptation to intensive muscular work in female sportsmen]

14 trained and 21 non-trained girls 18-22 years of age have been inspected. We found that systematically trained girls had a higher level of nitric oxide synthesis through calcium-dependent L-arginine oxidation by constitutive NO-synthase isoforms (eNOS, nNOS) and through reduction of stable oxidized NO metabolites. NO synthesized de novo in calcium-dependent pathway provides a long-term organism adaptation to physical loads of high volume and intensity at the beginning and in the middle of stress-aggravated competition period. At the end of competition period we detected significant activation of inducible calcium-independent de novo NO synthesis from L-arginine.

[Effect of nitric oxide on Na+, K(+)-ATPase in the aorta tissue of rats]

The influence ofnitric oxide on Na+,K(+)-ATPase activity in rat aorta was studied by means of stimulation of endogenous NO synthesis after injections of bacterial lipopolysaccharide (LPS) and pharmacological NO donor nitroglycerine (NG). It was shown that NO action on Na+,K(+)-ATPase in vivo is dose-dependent. Stimulation of the endogenous NO synthesis by LPS as well as the administration of low doses of NG lead to the activation of Na+,K(+)-ATPase and favor the conclusion that NO-dependent Na+,K(+)-ATPase stimulation mediates vasodilatory and hypotensive action of nitric oxide. The Na+,K(+)-ATPase activity in rat aorta depends on the balance between the level of reactive oxygen and nitrogen species (ROS and RNS), formation of NO depots in the tissue of aorta as high- and low molecular weight nitrosothiols, and also on the intensity of free-radical reactions resulting in the generation of hydroperoxide radicals. The results obtained suggest that NOS- and cGMP-dependent pathway takes part in Na+,(+)-ATPase activation by LPS and NG, but the enzyme inhibition by nitric oxide in vivo is not cGMP-dependent and is determined by the activation of free-radical reactions and dramatic enhancement of nitrosylation level in rat aorta tissue.

[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.

[Effects of uncoupling proteins on nitric oxide synthesis and oxidative stress development in ishemia-reperfusion of old rat hearts]

Genipin is aglycone of geniposide, one of the active compounds of Gardenia gasminoides Ellis. The gardenia fruit extract has been used in traditional Chinese medicine to relieve the symptoms of type 2 diabetes that is accompanied with extensive oxidative stress and endothelial dysfunction of NO production. Besides, genipin was shown to inhibit UCP-depended proton leak through the inner mitochondrial membrane that leads to increased membrane potential and ATP production. We studied the effects of genipin at ischemia/reperfusion-induced oxidative stress and activity of NOS isozymes using Langendorfperfused old rat heart model. Ischemia/reperfusion is well-known oxidative agent, and showed significant increasing of superoxide radical, hydrogen peroxide and hydroxyl radical. Genipin application in doze 10-5 mol/L for 15 min before prolonged ischemia exerted powerful antiradical and antilipoperoxidative effects. Heart ischemia/reperfusion was supported with peroxynitrite generation and nitrozative stress. We demonstrated the inhibitory property of genipin on INOS expression that possibly occurs via protein kinase A inhibition and stabilization of I-kappaB-NF-kappaB complex. Genipin stimulated cNOS activity seemingly activating PI3K/Akt signaling pathway. Although, post-ischemic recovery ofcardiodynamic parameters of old rat hearts were depressed due to "switching off" the NO production by inducible NOS which is important in early period of reperfusion. Thus, we conclude that genipin is powerfull antioxidant and posses insulin-like activity due to its property of managing the NO production at intracellular signal transduction cascade level.

[The inhibition of oxidative and nitrosative stresses by ecdysterone as the mechanisms of its cardio- and vasoprotective action in experimental diabetes type I]

Streptozotocine (STZ) administration (5 mg/100 g) up regulates oxidative (lipid peroxidation as a marker) and nitrosative (protein nitrosilation as a marker) stresses as well as ROS (O(2-), H2O2, OH) generation in heart and aorta in rats after 60 days of STZ action. The level of oxydative stress was higher in aorta. Xanthine oxidase (XO) activation (uric acid as marker), but not lipoxygenase (LTC4 as marker) or cyclooxygenase (TxB2 as marker) are the main oxydases that generate O(2-) as calculated by correlation analysis. STZ administration led to sphingosine pools up regulation in heart and aorta, but pools of polyamines in this organ was down regulated. C27-phytosteroid hormone ecdysterone (100 ng/100 g, per os, 60 days) mimics the action of its structural analog C27-steroid hormone calcitriol (1alpha,25-dihydroxyvitamin D,) and protects rise of ROS generation (by XO inhibition), lipid peroxidation, protein nitrosilation, polyamine degradation in heart and aorta of rats after STZ administration. The new mechanism of iNOS activation, prostaglandine and tetrahydrobiopterin synthesis stimulation by ecdysterone has been proposed. It was due to stimulating enzymatic degradation of sphingosine-1-phosphate as effective regulator of iNOS, COX and GTP-cyclohydrolase in cardio-vascular system: sphingomyelin > ceramide > sphingosine > S-I-P > phosphoethanolamine > ethanolamine.

[Role of non-haem iron in protecting effect of ecdysterone on development of streptozocin-induced hyperglycaemia in rats]

Chronic hyperglycaemia (60 days) which developed after streptozotocine (STZ) administration (5 mg/100 g) in rats was accompanied with development of severe endothelial dysfunction as well as with disturbed non-haem iron metabolism. It was established by EPR spectroscopy method that STZ administration reduced transferrin levels in the blood as well as pools of iron associated with blood transferrin and with ferritin in the heart and aorta of rats with hyperglycaemia. Chronic ecdysterone administration (100 ng/100 g, 60 days) protects hyperglycaemia development by preventing of non-haem iron metabolism disturbance. These data suppose participation of non-haem iron in mechanisms of ecdysterone protection of streptozotocine-induced hyperglycaemia and ischemia.

[Mitochondrial permeability transition pore opening inhibition by ecdysterone in heart mitochondria of aging rats]

Nitric oxide reacts rapidly with superoxide to produce the potent oxidant peroxynitrite. In vivo mitochondria produce superoxide as well as NO. In heart mitochondria of aging rats the amount of NO and O2(-) are increased thus the levels of peroxynitrite produced may be increased too, in this reason mitochondria may be a major site of peroxynitrite formation. Oxidative stress induces cyclosporine A-sensitive mitochondrial efflux of calcium and proapoptotic factors through MPTP (mitochondrial permeability transition pore) opening in heart mitochondria which may contribute to tissue damage and mitochondrial dysfunction in aging rats. We tested the levels of NO and superoxide generation in mitochondria simultaneously with cyclosporine A-sensitive MPTP opening by Ca2+ and phenylarsine oxide (PAO) to determine whether downregulation of both NO and O2(-) generation in heart mitochondria by potent steroid antioxidant and free radical scavenger ecdysterone may protect heart mitochondria of aging rats again tissue damage. C27-phytosteroid hormone ecdysterone (10 mkg/100g, per os, 2 weeks) mimics action of its structural analog C27- steroid hormone calcitriol (1alpha,25-dihydroxyvitamin D3) and exert its cardio protection in aging heart mitochondria by inhibition of MPTP opening with effectivity of action of hormone melatonine (150 mkg/100g, 2 weeks [ V.F. Sagach et al. Fyziol. J (Ukr), 2006, 52(2), 3-15]). MPTP inhibition is dependent on paradoxycally high activation by ecdusterone of oxidative degradation of L-arginine by mtcNOS in mitochondria, by downregulation of superoxide generation and L-arginine degradation by arginase II and NO generation by mtiNOS in de novo and by NADP-dependent mtNR (nitrate reductase) in salvage pathways. These results suggest that MPTP opening may be directly influenced by ecdysterone signaling in mitochondria. The signaling pathway by which ecdysterone may coregulate the O2(-) and NO generation in heart mitochondria of aging rats may involve an outer mitochondrial membrane estrogen receptor coupled to mitochondrial PI3K/Akt/PKB activation results in superactivation and constitutive NO synthesis by mtcNOS.