[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.

[Modulating effect of Serratula coronata extract on nitric oxide metabolism in the aorta tissues of rats in lead intoxication]

Vasotoxic effect of prolonged lead exposures and the efficiency of vasoprotective effect of S. coronata extract per os addition is estimated in rats aorta It is established that lead in aorta causes a significant increase in reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation by increasing the activity of inducible isoform of NO-synthase (iNOS). The use of S. coronata extracts promotes ROS and RNS production decreasing by normalyzing the iNOS activity in exposures to lead acetate rat aortas.

[Effect of enalapril on nitric oxide synthesis, oxidative metabolism, and vascular tone in aging rats]

Endothelium-dependent and endothelium-independent reactions of relaxations of vascular smooth muscle (VSM) were examined in the aorta preparations of the two groups (6-8 and 21-22 month). The studies also two NO synthase (NOS) isoform activity--inducible (iNOS) and constitutive (cNOS), activity of arginase and nitrate reductase and the content of high-molecular nitrosothiols (HMNT) and low-molecular nitrosothiols (LMNT) and stable metabolites of NO (NO(-)2, NO(-)3). Aging rats demonstrated only endothelium-dependent responses of VSM to acethylcholine lowering. This endothelial dysfunction depend on high activity of arginase, iNOS and salvage (by nitrate reductase) NO synthesis, both reactive oxigen species (ROS) (by xanthine oxidase) and peroxynitrite generation, as well as low activity of constitutive (eNOS, nNOS) NO synthesis. Angiotensin-converting enzyme inhibitor (enalapril) administration (20 mg/kg, 30 or 55 days) up regalate constitutive NO synthesis by arginase, iNOS, nitrate reductase activity and ROS and peroxynitrite generation inhibition thus restore endothelium-dependent relaxations of VSM in aging rats. The result obtained suggest a new roles for the renin-angiotensin system in vascular tone regulation. Thus enalapril might serve as a novel tool to prevent aging-associated endothelial dysfunction.

[Normalizing effect of intermittent hypoxic training on the function of endothelium in experimental diabetes mellitus]

The purpose of the study was to investigate changes of endothelial function at experimental diabetes mellitus under the action of interval hypoxic trainings (IHT). A decrease of hyperglycemia and normalization of endothelium-dependent vascular reactions are shown after IHT. Activity of constitutive NOS in the heart after IHT increases considerably while activity of inducible NOS decreases sharply. Considerable diminution of iNOS activity after IHT also registered in aorta. Nitrite-anion content (NO2-) increased both in the heart and in aorta. IHT results in diminishing level of such markers of oxidizing stress as a hydrogen peroxide and dien conjugates. Thus, the action of IHT consist in diminishing ofhyperglycemia, decline of expressed of oxidizing stress, partial normalization of synthesis of nitric oxide and renewal of endothelial function in rats with experimental diabetes.

[The role of nitric oxide and superoxide synthesis in protective mechanism of ecdysterone in the heart mitochondria of rats with streptozotocin-induced diabetes]

This study evaluated generation of O2*- and NO in heart mitochondria isolated from 9-week old streptozotocin (STZ)-induced diabetic rats and the effect of ecdysterone treatment on these parameters. Mitochondria isolated from 9-week old placebo-treated rats were used as control. Several parameters were evaluated: O2*- production, the levels of stable NO metabolites nitrate, nitrite and total nitrosothiols, the level of bilirubine (as marker of CO generation), inducible (iNOS) and constitutive (nNOS) mtNOS, NADH- dependent nitrate reductase (NR) and inducible arginase II (AII) activity. We observed that diabetes was accompanied by a significant decrease in nNOS activity, nitrite, total nitrosothiols and bilirubine content while iNOS, NR and AII activity, as well as O2*- generation was increased in heart mitochondria. Ecdysterone treatment normalized the levels of stable NO metabolites, ability to generate superoxide, iNOS and nNOS activity, but not bilirubine level, NR and AII activity. These results suggest that ecdysterone treatment attenuates diabetes-induced mitochondrial alterations protecting against oxidative and nitrosative stresses. Thus, ecdysterone therapy, besides its well known importance in the maintenance of glycemic control, may help to protect against mitochondrial dysfunction associated to several age-related disorders.

[NO-dependent mechanisms of ecdysterone protective action on the heart and vessels in streptozotocin-induced diabetes mellitus in rats]

Ecdysterone (100 ng/100 g) chronic oral administration (2 months after STZ (5 mg/100 g) administration) normalized plasma glucose levels in rats. This potent hypoglycemic effect of ecdysterone depend on inhibition of non-constitutive NO synthesis by Ca(2+)-independent iNOS and NADP-dependent nitrate reductase as well as inhibition of L-arginine degradation by arginase result in up-regulation of Ca(2+)-dependent constitutive NO synthesis by eNOS or mithochondrial nNOS in heart and aorta of rats.

[Effect of enalapril on endotheliun-dependent contractile reactions and oxygen cost of work of the smooth muscles in experimental diabetes mellitus]

The influence of angiotensin-converting enzyme on endotheliun-dependent contractile vascular reactions was investigated on the rat model of streptozotocin-induced diabetes mellitus. It is shown, that the long-term administration of enalapril results in partial restoration of disturbed at diabetes mellitus reactions and also to reduction of oxygen cost of smooth muscles and myocardial work. Thus, after 28-day's of oral administration of this drug the restoration of endotheliun-dependent dilatation of aorta and coronary vessels, increase of stretch-induced contractile responses of vascular smooth muscles, reduction of stiffness of isolated portal vein strips are observed. Possible mechanisms of such changes are following: increase of nitric oxide synthesis (at the expense of constitutive NOS activity) and reduction of oxidative stress, to what the decrease of diene conjugates contents in tissues of animals with diabetes mellitus after long introduction of enalapril testifies.

[Melatonin recovers ischemic tolerance and decreases the sensitivity of mitochondrial permeability transition pore opening in the heart of aging rats]

The effect of the hormone of pineal gland melatonin on the ischemic tolerance and the sensitivity of mitochondrial permeability transition pore opening in old rat heart were studied. It has been shown in the Langendorf's isolated rat heart that heart contractile functional changes under ischemia and reperfusion were more pronounced in old (24-27 months) rat hearts in comparison with the adult (5-6 months) animals. A two-week's in vivo course of intraperitoneal injection of melatonin (1,5 mg/kg weight) to old rats contributed to the rehabilitation of the functional changes of isolated heart after ischemia during reperfusion and decreased the sensitivity of mitochondrial permeability transition pore opening to Ca2+ and phenilarsinoxide in comparison with old animals which did not received melatonin. It was accompanied by the significant decreasing in mRNA bax expression in old rat heart, lessening in content of the superoxide radicals and dien conjugates and twice increasing in the activity of constitutive NO-synthase in heart mitochondria of old rat after a course of melatonin injection. The protective feffect of melatonin on the mitochondrial permeability transition pore opening could be used for correction of the cardiac dysfunction with aging.

[The effects of alpha-linolenic acid on the functioning of the isolated heart during acute myocardial ischemia/reperfusion]

Many studies indicate that dietary omega-3 polyunsaturated fatty acids (PUFAs) have the cardioprotective properties. But majority of experiments were carried out with using omega-3 PUFAs from marine fish oil. The purpose of this study was to determine effects of the plant-derived omega-3 PUFA (alpha-linolenic acid (a-LA) on postischemic myocardial dysfunction, lipid peroxidation and antioxidant enzymes activity. Male Wistar rats (250-300 g) were divided into 4 groups (n = 10-12 each). In control group (1) were intact rats. The hearts from 2-nd group of animal were exposed to 20 min of global ischemia followed by 40 min reperfusion according to the Langendorff technique. The 3-rd and 4-th groups of animal received of the plant-derived oil (a-LA), which is a precursor of eicosapentaenoic acid and was used as a dietary supplement in dose 0.1 mg/kg per day for 4 weeks. The hearts from 4-th group of animal were also exposed to ischemia/ reperfusion. Analysis of myocardial phospholipid fatty acid content showed that consumption of the plant-derived 6-LA for 4 weeks changes fatty acid profile through incorporation of b-LA in cell membranes. It also reduced content of omega-6 PUFAs in membrane phospholipids. In 3-rd group content of a-LA and EPA were increased by 1.5- and 3.5-times, respectively, whereas content of AA was reduced by 1.7-times. The development of ischemia/ reperfusion in 2-nd group caused increase of free AA content in heart tissue by 3.5-times, whereas in 4-th group this increase was only by 1.4-time. Ischemia/reperfusion of the isolated rat heart in 4-th group was accompanied by reduced leukotriene C4 and thromboxane B2 production in 3-times and 1.9-times, respectively in comparison to 2-nd group. The time of myocardial function recovery after ischemia (heart rate, left ventricular development pressure), was shorter compare to 2-nd group. Also in 4th group end-diastolic pressure and coronary perfusion pressure during reperfusion period were significantly lower. Dietary omega-3 PUFAs resulted in remarkable decrease of reperfusion arrhythmias in 4-th group (in 3.8-times) and limited the oxidative stress through decrease free radical and lipid peroxidation production. In this group of animals the activity of antioxidant enzymes (superoxide dismutase and catalase) after ischemia/reperfusion were higher than in 2-nd group. We suggest that dietary supplement of the plant-derived alpha-LA for 4 weeks have cardioprotective effects similar to the effects of fish oil.

[Mechanisms of contractile reaction changes and efficiency of oxygen utilization by portal vein smooth muscles in experimental diabetes mellitus]

On the rat portal vein isolated strips the essential reduction of contractive response, increase of stiffness of vascular smooth muscles at their stretching and increase of oxygen value of smooth muscles' work are revealed in conditions of experimental diabetes mellitus. The possible mechanism of such infringements is chronic hyperglycemia, which results in development of oxidative stress and reduction of NO synthesis by constitutive NOS. Indeed, the significant decrease of activity of constitutive NO-synthase and increase of the oxidative stress markers contents are shown at experimental diabetes mellitus. The similar infringements are marked at in vitro model of hyperglycemia, blockade of NO-synthase and in conditions of oxidative stress. Additional confirmation of a role of NO synthesis blockade and oxidative stress in development of such infringements at diabetes is fact that application of antioxidant melatonin and L-arginine, a precursor of NO to diabetic animals results in partial restoration of contractive reactions, reduction of stiffness and oxygen value of smooth muscles' work.

[Effect of heme oxygenase-1 expression and activity on the heart function in ischemia-reperfusion]

The purpose of this study was to determine the protective effects of heme oxygenase-1 (HO-1) expression against postischemic myocardial dysfunction. We also investigated HO-1 expression in cardiac tissue from the left and right ventricles of myocardium. Rat hearts were isolated and perfused according to Langendorff technique to evaluate the recovery of myocardial function after 20 min of global ischemia and 40 min of reperfusion. We found that HO-1 expression was more expressed in left ventricles of myocardium in basic conditions and after ischemia/reperfusion as well as after its previous induction by hemin. Upregulation of the inducible isoform of HO-1 and increase its activity after treatment of animals with hemin 24 h before ischemia ameliorated myocardial function (raised left ventricular developed pressure, decreased end-diastolic pressure, attenuated vasoconstriction) and reduced oxydative stress in cardiac tissue during reperfusion of isolated hearts. Zinc protoporphyrin IX, an inhibitor of heme oxygenase activity, completely abolished the HO-1 expression in left ventricles of myocardium and increased postischemic myocardial dysfunction. Likewise, cardiac tissue injury was exacerbated by treatment with zinc protoporphyrin IX through significant inhibition of HO activity and increasing of hydroxyl radical production on reperfusion. The treatment of animals with hemin and following ischemia/reperfusion resulted in 5-6-times increase of HO-1 expression in the left ventricle of myocardium whereas in right ventricle only in 3-times. Our data provide strong evidence for a primary role of HO-1 in cardioprotection against reperfusion injury and show different HO-1 expression in left and right ventricles of myocardium.

[The effects of omega-3 polyunsaturated fatty acids on lipid peroxidation]

The aim of this study was to evaluate the effects of a diet supplemented with omega-3 polyunsaturated fatty acids (PUFAs) (plant-derived alpha-linolenic acid and eicosapentaenoic and docosahexaenoic acids with alpha-tocopherol (product "Tekom") on the myocardial phospholipid fatty acids composition, lipid peroxidation and activity antioxidant enzymes--superoxide dismutase and catalase in myocardial tissue in control and after ischemia/reperfusion of isolated working rat hearts. Inclusion of omega-3 PUFAs into the animals' diet within 4 weeks demonstrated that alpha-linolenic acid and "Tekom" increased omega-3 polyunsaturated fatty acids content in cardiomyocytes membranes and limited lipid peroxidation (decreased content of congugates of dienes and malone dialdehyde, reduced hemiluminescence of myocardial tissue). Additionally omega-3 PUFAs caused the beneficial effects on activity of antioxidant enzymes in cardiac tissue (increased superoxide dismutase and catalase activity).

[The modification of nitric oxide production by exogenous substrates of Krebs cycle during acute hypoxia]

Hypoxia causes the disruption of mitochondria electron respiratory chain, production of active oxygen forms and the unoxidative protection. In experiments on Wistar rats the influence of sodium succinate (50 mg/kg) and 6-ketoglutarate (200 mg/kg) on NO2-, NO3-, urea and polyamines contents in blood and liver under acute hypoxia (7% O2 in N2, 30 min) was investigated. Nitrite and nitrate content decreased in erythrocytes and liver but not in plasma under acute hypoxia. The exogenous succinate (SK) stimulated production of nitric oxide in erythrocytes and liver while 6-ketoglutarate (KG) only in liver. The switch from more intensive SK oxidation that reveals adrenomimetic influence and causes the synthesis and release of NO from erythrocyte, to less intensive KG correlates with well-known decrease of tissue respiration under the activation of the cholinergic system due to urea cycle activation particularly in liver. The activation of the SK oxidation takes place mainly under the different stress conditions and causes NO production in the blood cells. These conditions of the intensive and fast action under acute hypoxia are accompanied on the one hand by the increase of oxygen input ratio and on the other hand by activation of the free radical oxidation. The protective effect of the natural Krebs cycle intermediates--SK and KG in particular, is related to the regulation of NO synthesis and its metabolism in the main organs. These results proved the existence not only metabolite control of NO system by Krebs cycle intermediates, but the existence of the systemic mechanism for the support of the functional state of mitochondria under hypoxia.

[Effect of L-arginine on the endothelium functional activity in experimental diabetes mellitus]

The experimental data about the shift of L-arginine metabolism in the direction of activization of non-oxidizing (arginase) way under experimental diabetes mellitus are presented. This shift was proved by an increase of the ratio of arginase and NO-synthase activity and an increase of the ratio of their metabolites. The decrease of the free L-arginin contents in tissues of animals with experimental diabetes mellitus is shown. The long infusion of L-arginine results in the restoration of the endothelial function, however cessation of infusion results in a gradual reduction of this effect.

[Age-related characteristics of contractile vascular reactions and the content of oxygen free radicals and nitric oxide metabolites in BALB/c mice in conditions of alienation zone]

Peculiarities of changes of the endothelium-dependent and endothelium-independent vascular reactions of relaxation, and the content of oxygen free radicals and stable metabolites of nitric oxide (NO) were studied in the aorta preparations of BALB/c mice of the two age groups (6 and 18 months), which were born and lived in the Chernobyl alienation zone. The results obtained showed no endothelium-dependent reactions of aortal smooth muscles relaxation to acetylcholine and only partially impaired endothelium-independent reactions to sodium nitroprusside in animals of both age groups. There was a significant decrease in the content of high-molecular nitrosothiols (HMNT) in old animals, which may signify a depletion of NO depot in the aorta. A decrease of HMNT levels induced an increase of the shares of anion nitrite and low-molecular nitrosothiols (LMNT) in the total amount of endogenous donors of NO in the aorta of old animals. Exposure of old animals to low doses of radiation resulted in an over 3-fold increase of LMNT. In old mice the levels of oxygen active forms, superoxide and hydroxyl radicals increase, while the level of H2O2 remained unchanged.

[Nitric oxide suppresses permeability transition pore opening and enhances calcium uptake in mitochondria in vivo]

The influence of an NO donor, nitroglycerine (NG) on Ca2+ accumulation in rat heart and liver mitochondria was studied. A rapid dose-dependent increase in Ca(2+)-uptake was observed within 5 min after NG injection in vivo, with a peak in NG concentration of 0.5-1.0 mg/kg body weight. There is a correlation between a dose-dependent increase in Ca(2+)-accumulating capacity of mitochondria and sharp dose-dependent rise in stable NO metabolites level (NO2-, NO3- and nitrosothiols) and reactive oxygen species (H2O2 and hydroxyl radical, *OH) as well as lipid oxidation products (diene conjugates), the markers of the oxidative damage of the organelles in mitochondria in comparison to a whole tissue (liver) where only moderate increase of ROS and NO metabolites was detected. A 20-30-fold increase of NO3- level from 32. +/- 2.6 to 736.4 +/- 96.5 nmol/mg protein (p < 0.05) and from 45.4 +/- 6.2 to 1395.0 +/- 121.1 nmol/mg protein (p < 0.05) in liver and heart mitochondria respectively also provide a strong evidence for nitrosative stress. The results obtained suggest that calcium elimination from cytosol and its increased accumulation in mitochondria (likely dependent on permeability transition pore blockade by NO) could account for the cardioprotective action of NG although resulted in the development of oxidative stress with following long-term alterations of the energy supply and metabolism of subcellular structures.

[Sensitivity of phenylarsineoxide-induced mitochondrial permeability transition pore opening in the heart of old rats during intermittent hypoxic training]

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.

[Human heart and endothelium functional activity depending on age and sex]

The complex study ofcardio-hemodynamics and functional activity of the endothelium in healthy persons of different age allowed us to establish that aging accompanied with a gradual worsening in the endothelium functioning with resulting increase in peripheral vascular resistance and blood pressure as well as decrease in the myocardial contractile activity. Such age shifts might be involved in pathogenesis of cardiovascular diseases, which prevalence is highly rises with increased age. Analysis of sex difference in the endothelium functioning showed a progressing lowering of the endothelium-dependent vasodilatory reaction to begin in the men as early as after 40 years of age. This leads to the decrease in the vasodilatory reserve with increase in peripheral vascular resistance and blood pressure. Worsening in the myocardial contractility in 40-year men can be also stipulated by changing in the endothelium synthetic activity that was evidenced by decrease in plasma levels of NO stable metabolites. In the women, such a lowering of the endothelium functional activity begins 10 years later and progresses more slowly compared to the men. The rate of worsening in the endothelium functioning in the men is twice of that in the women. Therefore, the elderly women have the endothelium to be 20 years "younger" than that in the elderly men, and perhaps namely this explains the better functioning of the cardiovascular system in the elderly women. So, a functional activity of the endothelium can be a main age and sex determinant, which stipulates well-known age and sex differences in prevalence of cardiovascular diseases and life expectancy. Prevention of the endothelium function disturbances might lead to the alignment of the differences between men and women in prevalence of cardiovascular diseases and life expectancy, decrease in general morbidity with improvement of life quality in elderly.

[Acute myocardial ischemia-reperfusion injury: role of nitric oxide system]

In experiments on the closed-chest dogs it was shown that NOS inhibition resulted in the significant alterations of hemodynamic indices (coronary and peripheral vascular resistance, cardiac output and heart rate) under local myocardial ischemia/reperfusion in comparison with control experiments. At the first time it was shown that NOS inhibition activated the autophagic destruction of cardiomyocytes in the ischemic myocardium and could reduce an area of functionally active myocardium. L-arginine administration attenuated cardio- and hemodynamic disturbances, that substantially improved the course of ischemia/reperfusion, diminished the ultrastructural changes in myocardium and prevented development of autophagic programmed cell death.

[Inhibitors of arginase pathway in L-arginine metabolism as a new class of antihypertensive drugs: action of urea on oxidative and nonoxidative metabolism of L-arginine and vascular tone in chronic hypertension]

It has been studied an action of chronic urea introduction (40 mg/kg, 14 and 28 days) as arginase inhibitor on nonoxidative (arginase activity, urea, polyamines content) and oxidative (NOS activity, nitrite- and nitrate-anion content) metabolism of L-arginine in aorta, heart, plasma and erythrocytes of SHR. It has been shown that urea is an inhibitor of not arginase only, but also ornitinedecarboxilase (ODK) reactions, limiting L-arginine consumption for urea and polyamines synthesis and thus facilitating its utilization for nitric oxide synthesis by NOS. These exogenous effects of urea are not accompanied by amelioration of tissue ischaemization within cardiovascular system. It has been shown that exogenous urea down regulate blood pressure without any normalization of endothelim-dependent reactions of smooth muscle cells on acetylcholine in SHR.

[Effect of modification in cell membrane fatty acid composition on adrenergic cardiac and vascular reactivity]

The work is dedicated to examination of the effect an omega-3 polyunsaturated fatty acids (PUFA) on vascular and cardiac reactivity in intact animals. In experiments on isolated perfused rat hearts and isolated rings of rat aorta it was shown that reactivity in rats with modified membranes was lesser than in control animals after adding norepinephrine in raising concentrations. Use of omega-3 PUFA resulted in the decrease of omega-6 PUFAs (arachidonic acid (AA)) content, while omega-3 PUFAs (EPA, DHA) content in cardiomyocytes membranes increased. Besides that it was shown that after omega-3 PUFA enriched diet NO3- content increased in cardiac tissues and blood.

[Expression of markers of immunocompetent cells, cytokine level, and L-arginine metabolism in complex extremely high frequency and interferon therapy of inflammatory diseases in women of highlands]

Chronic inflammatory gynecological diseases (CIGD) in highlanders (2,100-2,200 m a.s.l.) are accompanied with the following changes in immunoregulatory parameters: strengthening in the expression of CD3+ (TCR), CD4+ (T-helpers), CD16+ (NK-cells), CD25+ (activated IL-2R), increase in CD4+/CD8+ ratio, levels of circulating cytokines--alpha-, beta-, gamma-interferon (IFN) and alpha-, beta-tumor necrotizing factor (TNF), strengthening in immune adhesion of thrombocytes (IAT), and inhibition of the oxidative metabolic way of L-arginine with redistribution of the main metabolites formed via its non-oxidative way. Complex extremely high frequency (EHF) therapy and interferon (with Laferon) therapy of CIGD normalized expression of the differentiated and functional CD-markers of immunocompetent cells (ICC), CD4+/CD8+ ratio, increased expression of CD8+, decreased IAT and levels of circulating cytokines (IFN, TNF), changed L-arginine metabolism with activation of the oxidative way. Full-value of the population signs of immune stabilization due to the treatment was complemented with increase in the ICC functional parameters--markers of mitochondrial, lysosomal and mitotic activity. We first demonstrated a high effectiveness of complex use of EHF and Laferon as an immunocorrective therapy of CIGD in highlanders.

[NO-dependent effects during adaptation of rats to intermittent hypoxia]

In experiments on Wistar rats processes nitric oxide production on concentration of anions (NO2-, NO3-), carbamide and polyamines contents were investigated in processes of rats adaptation to acute hypoxia (7% O2 in N2, 30 min) and intermittent hypoxia training (10% O2 in N2, 15 min, 5 cycles daily) during 14 days. NO production by oxygen-dependent and oxygen-independent metabolites paths has been investigated. It is concluded that the disturbances in nitric oxide system induced by acute hypoxia by L-arginine injections may result in acute hypoxia.

[Expression of iNOS and activities of iNOS and cNOS in right and left ventricles of the isolated heart during ischemia and reperfusion]

Isolated using Langendorff technique hearts of male Wistar rats were ischemized for 30 min and reperfused for 40 min. Both iNOS expression determined by immunoblotting, and its activity shown by a modified Griess method have been found to predominate in the right ventricle over the left one, as compared to cNOS activity which prevailed in the left ventricle. The latter significantly diminished after an ischemic injury in the left ventricle. On the contrary, an expression of iNOS and the total NOS activities increased progressively after ischemia and postischemic reperfusion; all the values in the right ventricle were higher than in the left one. The high level of iNOS expression in the right ventricle in a postischemic period decreased during reperfusion, although an activity of the enzyme went on elevating. These data can give an evidence for different regulation of NO synthesis in right or left ventricles of the heart, including normal conditions or ischemia.

[Effect of irbesartan--angiotensin II type I receptor inhibitor on oxidative metabolism of lipids in essential hypertension]

We evaluated the alters in plasma vasoconstriction eicosanoids (LTC4, TXB2) and diene conjugates (DC) levels in patients with essential hypertension (EH) after chronic (30 days, 235 mg per day) of irbezartane (inhibitor of ANG II type 1 receptor with prolongation action "Aprovel" from "Sanofi") oral administration. Patients with EH have significantly higher plasma both LTC4, TXB2 and DC levels then healthy controls. This imbalance can be beneficially modulated by chronic irbezartane ("Aprovel") administration. It is concluded that ANG II type 1 receptors can be involved in regulation of free arachidomc acid oxidation.

[Increased level of nitric oxide stable metabolites in the blood of highlanders]

The investigation was designed to study nitric oxide (NO) blood level estimated by measuring its stable metabolites nitrite (NO2-) and nitrate (NO3-) concentration in highlanders (2,200 m a.s.l.). NO2- [symbol: see text] NO3- concentration was measured with Griss reagent and brucine reagent respectively with using the spectrophotometric method. We first found that highlanders compared to lowlanders have increased blood level of NO2- (37 +/- 3.3 nmol/ml vs. 28.5 +/- 1.3 nmol/ml, P < 0.05) and NO3- (1362 +/- 43 nmol/ml vs. 845 +/- 65 nmol/ml, P < 0.001). As the most significant, there was increase in NO2- concentration in erythrocytes (by about 6 times), NO3- level in erythrocytes was revealed to be increased by 2.5 times, whereas the plasma concentration of these stable metabolites was the same (for NO3-) or even slightly decreased (for NO2-). Such increased NO stable metabolites blood level in highlanders may explain widening of vasodilative reserve and strengthening of cardiac pump and contractile functions, which we revealed previously. Activation of NO-system in high altitude is important and probable trigger adaptive mechanism of cardiovascular system to hypoxia. This mechanism allows to retain adequate tissue perfusion and optimal oxygen supply in its decreased partial pressure in inhaled air and thereby to prevent diseases caused by vasospastic processes.