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The influence of indometacine (7 x 10(-8)M) on the tonic contractile activity of the isolated rat portal vein (PV) under the action of adrenaline (1 x 10(-5)M) and noradrenaline (5 x 10(-6)M) was studied. Indometacine decreased the amplitude of noradrenaline-induced tonic constriction of PV with intact endothelium and produced no effect on constriction of vessels with denuded endothelial layer. The results suggest that these reactions are mediated by endothelial prostanoids. Inhibition of adrenaline-induced constriction of PV preparations with intact and denuded endothelium suggests that the contractile reactions are mediated by prostanoides derived from both endothelial and smooth muscle cells.

The effect of endogenous and exogenous hydrogen sulfide (H2S) on contractile activity of vascular smooth muscle (VSM) was studied. The introduction of substrate synthesis H2S L-cysteine and its donor NaHS in vitro caused concentration-dependent relaxation of VSM of aorta and portal vein. Low concentrations of hydrogen sulfide donor (10(-5) mol/L) caused vasoconstriction of both types of the vessels. It was shown that the reaction of relaxation of VSM in response to NaHS is independent from endothelium. It was revealed that VSM of portal vein are more sensitive to the effects of H2S than VSM of aorta. Removing of aorta periadventitial adipose tissue showed no relaxation reply to the hydrogen sulfide donor NaHS in 70% of experiments. Some of the cellular mechanisms of hydrogen sulfide action were established, namely relaxation of aorta is depended on K(ATP) channel activation. This is manifested by a lack of relaxation of the aortic VSM due to K(ATP) channel inhibitor glibenclamide.

Because the sustained component of hyperpolarization of endothelial cells evoked by acetylcholine in isolated rat aorta may partially be mediated by the reversed Na(+)-Ca(2+) exchanger and Na(+)-K(+) ATPase, the mechanisms which transport Na(+) out of cells, we compared the electrical responses of endothelial cells from isolated rat aorta to acetylcholine with other Ca(2+) mobilizing agents and studied the effect of nicotine on endothelial membrane potential in order to asses the functional activity of nicotinic cholinoreceptors. Ca(2+) ionophores A23187 and ionomycin, as well as inhibitors of endoplasmic reticulum Ca(2+) ATPase cyclopiazonic acid and 2,5-di-tert-butylhydroquinone evoked a short-lived hyperpolarization which turned to a sustained depolarization of endothelial cells, a time course that substantially differed from that evoked by acetylcholine. Nicotine evoked a Na+ dependent depolarization of endothelial cells confirming functional activity ofnicotinic cholinoreceptors in rat aortic endothelial cells. The results suggest that stimulation of Na+ permeant nicotinic receptors by acetylcholine may contribute to sustained hyperpolarizatiom via stimulation of Na+ extrusion mechanisms.

The influence of mitochondrial uncoupling protein genipin on endothelium-dependent reaction of vessels, heart contractility and myocardial oxygen consumption was studied at streptozotocin-induced rat model of diabetes mellitus. The partial restoration of damaged at diabetes mellitus vascular reactions as well as decrease ofmyocardial oxygen consumption has been shown after intraperitoneal injection of genipin. For example, after the introduction of 10 mg/kg genipin were shown a partial restoration of endothelium-dependent dilatation of aorta and coronary vessels, increase of contractive strength-dependent responses of vascular smooth muscle, decrease of portal vein isolated strips stiffness, the improvement of contractive properties and decrease of myocardial stiffness. These data suggest a possible role for mitochondrial uncoupling protein in the development of changes of heart and vascular responses observed at experimental diabetes mellitus.

Experimental data regarding the features of the functional state of vascular endothelium in girls of 18-20 years old with a different level of physical activity are presented in the article. It is shown that systematic physical exercises (volley-ball game) cause substantial positive changes in endothelium-dependent physiological indexes.

The authors studied the influence of lozartan -angiotensin II antagonist on the state of cardiohemodynamics and function of vessel endothelial cell in patients with CODL in the process of the treatment. 90 patients with stage II or III CODL in remission (average age is 50.46+/-5.1) have been observed. The average duration of the disease was 16.2+/-7.6 years. 30 patients received additionally lozartan -angiotensin II antagonist. Cardiohemodynamics has been assessed using Doppler ultrasonography. To assess the state of function of vessel endothelial cell the authors carried out reactive hyperemia test and calculated the level of nitrite nitrogen in blood plasma and erythrocytes. The duration of observation was 12 weeks. Losartan appeared to be effective in patients with CODL to correct compromised cardiohemodynamics. Losartan dicreases the disfunction of endothelial cell and has cardioprotective properties.

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.

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.

It was shown in vitro that platelets of rats which were exposed to high-salt diet (3 % NaCl solution) possess the least functional activity, especially after addition of the vascular wall tissue to the incubating medium compared to intact rats, which had water load.

Membrane potential of aorta's endothelium, contractile responses of isolated preparation of the abdominal aorta and their modulation with calcium antagonists were studied at hypercholesterinemia (HHS). Membrane potential has been observed to be slightly depolarized at HHS, and acetylcholine-induced electric and contractile responses were shown to be depressed. Calcium antagonists had positive effect on MP, electric and contractile responses of the preparations of the abdominal aorta of rats with HHS. The most pronounced protective effect of membrane potential and contractile responses at HHS was observed in rats after asparcam using.

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.

The changes in electrical properties of intact aortic endothelial cells from streptozotocin-induced diabetic rats were investigated. The mean resting membrane potential of unstimulated endothelium was significantly less negative (-32.7 +/- 0.8 mV) as compared with the aged-matched control group (-41.2 +/- 0.9 MB). In diabetic rat aortic strips, acetylcholine (2 microM) hyperpolarized endothelial cells to -57.6 +/- 1.1 mV, whereas in control group the hyperpolarization reached -64.4 +/- 0.9 mV. The amplitude of the hyperpolarization in diabetic rats, however, was not significantly different from the control group (24.9 +/- 1.1 mV and 23.2 +/- 0.9 mV, respectively). It was concluded that endothelial cells of diabetic rat aorta have less negative membrane potential values at rest and during acetylcholine stimulation that may partially account for the suppressed endothelium-dependent relaxation in streptozotocin-induced diabetic rats.

Changes in cardiohemodynamics after intravenous administration of insulin (1.0 IU/kg) were investigated on anaesthetized dogs with closed chest. During the first 5-10 min (phase 1 of the response), coronary vasoconstriction, an enhancement of the cardiac activity and an increase in a coronary arteriovenous oxygen difference were observed. During the next 25-30 min (phase II) a long-term coronary dilation, an attenuation of the cardiac contractility and a decrease in the coronary arteriovenous oxygen difference occurred. An injection of insulin after preliminary inhibiting NO-synthase (L-MANE, intracoronary infusion, 1.0 mg/min), guanilatcyclase (100 micrograms ouabaine, intracoronary injection), Na+, K(+)-ATPase (methylene blue, intracoronary infusion, 5 mg/min) induced coronary vasoconstriction. Inhibiting muscarinic receptors with atropine (0.5 mg/kg i.v.) attenuated or absolutely abolished haemodynamic responses induced by insulin. Under beta-adrenergic blockade by propranolol (2.0 mg/kg i.v.) administrations of insulin resulted in coronary constriction, an augmentation of cardiac contractility and an elevation of the arterial blood pressure. The conception has being developed, according to which the degree and trends of induced by insulin changes in cardio-haemodynamics depend on the initial levels the sympathetic and parasympathetic activities, as well as on the synthesis of endothelial vaso- and cardiotropic substances, and their interactions with these systems.

The effects of blockade of glycolysis on the contractile activity of isolated vascular rings of both the pulmonary artery and, the thoracic aorta were studied under hypoxia in intact, denuded vessels and those with blocked myoendothelial electrical coupling. The blockade of glycolysis led to a reversion of a hypoxic contraction in the pulmonary artery but had no effect on hypoxic dilatation of the aorta. Hypoxic constriction of the pulmonary artery was abolished after denudation and stayed unchanged at the following blockade of glycolysis. Moreover, blockade of glycolysis had no effect on the hypoxic responses of the pulmonary artery after blockade of the myoendothelial gap junctions. The data suggest that hypoxic contraction of the pulmonary artery is endothelium-dependent, in contrast to the hypoxic dilatation of the aorta. It is likely that glycolysis in endothelial cells and myoendothelial gap junctions contribute to hypoxic pulmonary vasoconstriction due to formation and conduction the depolarizing electrical signals from endothelial cells to smooth muscles causing their contraction under hypoxia.

Membrane potential has been recorded from endothelial cells of the rat inferior vena cava. The resting membrane potential of venous endothelial cells was 69 +/- 4 mV, which was about 20 mV more negative than resting potential of rat arterial endothelial cells measured under the same experimental conditions. 40% of the vein studied demonstrated spontaneous oscillations of endothelial membrane potential. These oscillations were found to be Ca2+ action potentials generated in the vein smooth muscle and electrotonically transferred into the endothelial cells.

Changes in the electric reactions of intact endothelium of isolated rat aorta were studied in conditions of aging. A value of resting membrane potential of endothelium of old rats (24-26 mo) was significantly greater, than in control group of animals (6 mo). In responses to acetylcholine and ATP the old rats did not show a typical course of reactions, which was peculiar to control animals. Inability of old rats to produce a typical response to acetylcholine and ATP may signify a disturbance of links between endothelial cells, which resulted in functional clusterization of the latter. The data obtained suggest a possible mechanism of decrease in production and release of potent vasodilator--nitric oxide--due to changes that occur in the electric properties of endothelium in aging.

A new low-conductance cationic channel has been recorded with the patch-clamp technique in excised patches of the luminal membrane of intact endothelial cells. The channel had conductance of 5.4 pS and the lifetime of 46 ms. It was equally permeable for Na+ and K+, but impermeable to Cl-. The lifetime and probability of the open state of the channel were independent of the membrane potential.

Effects of ethanol on membrane potential and intracellular calcium concentration in intact endothelium of isolated pulmonary arteries were investigated. Ethanol evoked hyperpolarization and biphasic increase in [Ca2+]i in the endothelium due to both Ca2+ release from intracellular stores and Ca2+ entry from extracellular solution. These data allow endothelium-dependent dilation of pulmonary artery evoked by ethanol to be explained.

Information about fourteen allelic variants of promoter, exons and introns of a gene of endothelial NO-synhase (eNOS) dealing with their role in a susceptibility to cardio-vascular diseases has been reviewed. Data of the populational genetic studies, performed in different regions of the world, were analysed to show the interrelation between an availability of on allele in the genome and a risk of ischemic heart disease. The main attention was focussed on the clarification of a relation between some allelic variants of the gene and functional (biochemical) properties of the protein, encoded by this gene, as well as on two principal mechanisms of realization of the pathological allelic variants in eNOS gene: 1) forming the protein in an insufficient quantity or with an altered activity (an interrupted transcription, and stability of informational RNA, formation of a cathalitically deficient protein); 2) an increased protein degradation (due to an acidic hydrolysis or an enhanced proteasomal proteolysis). In practical aspect, the most important problem, according to the point of view of the authors, is that of searching the pharmaco-therapeutical remedies, able to influence the different stages of the molecular-biological realization of an altered eNOS gene (transcription, translation, posttranslational modifications and degradation). Clarification of the above pathogenetic mechanisms will open broad perspectives in constructing therapeutical schemes for individuals possessing the pathological alleles of this gene.

The electrophysiological properties of intact endothelial cells of isolated arteries from mice, rats, guinea pigs and rabbits have been studied. Endothelial cells in all studied arteries were electrically coupled and had similar membrane potentials. The electrical responses to acetylcholine and ATP in the arteries of both elastic and muscular type were qualitatively similar, but varied among species in the length and amplitude of different stages of the responses.

The influence of adrenoceptor agonists and changes in the intracellular cyclic nucleotide concentration on the membrane potential of an isolated endothelial cell layer from rabbit aorta has been investigated. The alpha 1-adrenoceptor agonist phenylephrine evoked deep depolarization of the endothelium of an intact aorta, but had a little effect on the membrane potential of the isolated endothelium. The nonselective adrenoceptor agonist noradrenaline, the beta-adrenoceptor agonist isoproterenol and the inhibitor of phosphodiesterases IBMX all strongly depolarized the isolated endothelium. These data suggest that the rise in cyclic nucleotide concentration depolarizes endothelial cells, and this fact may account for the noradrenaline-induced depolarization of the endothelium through beta-adrenoceptors.

The ionic nature of membrane potential and electrical reactions to vasodilators and vasoconstrictors of intact endothelium of rabbit aorta have been investigated. It has been shown that K+ and Na+, but not Cl- permeability form membrane resting potential. The endothelium was hyperpolarized by ACh. ATP produced the triphasic reaction of short small depolarization, hyperpolarization followed by depolarization. Both noradrenalin and serotonin evoked depolarization.

The influence of intracellular cyclic nucleotides concentration increase on the membrane potential of intact endothelium of isolated rabbit aorta has been investigated. Both applications of bucladesine, an adenosine 3',5'-cyclic monophosphate (cAMP) membrane permeable analogue, and phoshophodiesterase blockers 3-isobutyl-1-methylxanthine (IBMX) and theophylline depolarized endothelial membrane. IBMX-induced depolarization was significantly smaller then theophylline-induced depolarization. It could be explained by the existence of IBMX-insensitive phosphodiesterases. Non-selective protein kinase blocker H-7 did not affect on the both IBMX-stimulated and non-stimulated membrane potential of aortic endothelium. It has been shown that the IBMX-induced depolarization and ATP-induced depolarization correlate with high correlation coefficient.

Endothelial vasoactive agents such as endothelin, angiotensin, nitric oxide and others are essential in regulation of the Na-pump functions in vascular and others tissues. In our review the intracellular mechanisms of activating and inhibition of the Na+,K(+)-ATPase by endothelial vasoactive agents are discussed. In the control of vascular tone and heart function as well as the regulation of the Na-pump endothelial vasoactive agents act individually or in close interaction with other physiologically active substances including the ouabain-like factor, endogenous inhibitor of the Na-pump. Some aspects ouabain-like factor physiological action are under the discussion. Recent advances in study and comprehension of intracellular mechanisms the mediating role of endothelial agents in Na-pump regulation are reviewed also.

In experiments on guinea-pig isolated hearts, perfused under Langendorff preparation, it has been shown that heart volume load and inotropic stimulation were accompanied with an increase of nitric oxide synthesis (by 46 and 51% accordingly) and with a decrease in an oxygen cost of myocardial work. L-arginine or sodium nitroprusside administration resulted in a reduce of the oxygen consumption by 29% and a decrease of oxygen cost of myocardial work. Inhibition of NO-synthase activity lead to an opposite effect--an increase in both--O2 consumption and an oxygen cost of the heart work by 15 and 19%. The data obtained evidence that NO is a regulator of the oxygen consumption by tissues and it determines the oxygen cost of the myocardial work. Its lack can play an important role in the developing of pathological states of the cardiovascular system, which are followed with its insufficient synthesis.

Involvement of metabolites of arachidonic acid in electrical responses of rat aortic endothelium evoked by the agonist of aa1-adrenoreceptors, phenylephrine has been investigated. Our experiments suggest that phenylephrine evokes synthesis of thromboxane A2 in the rat aorta that is involved in the phenylephrine-evoked oscillations probably by increasing excitatory effect of the vasoconstrictor on vascular smooth muscle by the mechanism of positive feedback.

Effects of shear stress on intracellular Ca2+ concentration ([Ca2+]i) and membrane potential of intact endothelium of the rat aorta have been investigated. Shear stress and acethylcholine both evoked endothelium-dependent relaxation of the rat aorta, but in contrast to acethylcholine shear stress did not affect [Ca2+]i and membrane potential of the endothelium. These data do not corroborate the hypotheses on involvement of Ca2+ and membrane potential in reception of shear stress by endothelium.

The changes in the membrane potential (MP) of in situ endothelial cells from guinea pig aorta was studied using patch-champ technique under ATP stimulation. Extracellular ATP is shown to evoke the complex changes in endothelial MP: initial short-lived depolarization and subsequent maintained hyperpolarization. Extracellular calcium buffering as well as addition of extracellular Ni2+ made the hyperpolarization shorter. After the buffering of intracellular calcium ATP addition evoked only depolarization which was not observed in the absence of extracellular sodium. The hyperpolarization under ATP stimulation was absent after emptying of intracellular calcium stores. It was concluded that hyperpolarization in response to ATP is initiated by calcium release from intracellular stores followed by activation of calcium-dependent potassium channels, the maintained phase of hyperpolarization is provided by extracellular calcium entry and initial depolarization by extracellular sodium entry into EC.

The role of endothelium and its biologically active derivatives in the central and local control of circulation is under consideration. Molecular and cellular mechanisms of the activation of the endothelium-dependent responses of different functional significance are being discussed, as well as the state of endothelial responses in the development and compensation of pathological processes in the cardiovascular system.

The effects of vintoperol have been studied in the experiments on the vascular bed of femoral artery of 15 mongrel dogs under chlorazol-urethane narcosis and on isolated vascular preparations of rats. It is shown that ++de-endothelization of vascular bed using saponin and mechanical removal of endothelial stripes decreased the vasodilatation reaction and relaxation of stripes by 50-60% of the initial values. While infusing ventoperol (0.3 mg.kg-1 min-1) to ++de-endothelized vascular bed, the blood flow increased by 18 +/- 5% as against 47 +/- 3.9% of the initial value under intact endothelium. Blockade of guanylate cyclase by methylene blue decreased blood flow under vintoperol action to 24 +/- 3.5%. The similar results are obtained in the experiments in vitro. After ++de-endothelization of pulmonary artery++ the amplitude of relaxation of preactivated smooth muscles decreased vs. initial tone (21 +/- 3.7% vs. 56% +/- 5.3%). Inhibition of relaxation reaction of vascular stripe under vintoperol effect is also observed after treatment with gossypol, or methylene blue. Thus, endothelium is involved in the realization of vasodilating effect of vintoperol, its action being mediated by endothelium--derived relaxing factor.