Role of H2S in Regulation of Vascular Tone in Metabolic Disorders

We studied the effect of the H₂S donor (NaHS, 1-500 μM) on the contractile responses of isolated aortic smooth muscle segments from rats with metabolic syndrome induced by high-fat, high-carbohydrate diet. It was found that the vasorelaxing effect of NaHS (5-100 μM) decreased in under conditions of MS. The endothelial NO synthase inhibitor L-NAME (100 μM) suppressed the effect of NaHS, while cystathionine-gamma-lyase inhibitor PAG (100 μM) decreased the vasodilating effects of acetylcholine (0.1-100 μM). Application of endogenous NO precursor L-arginine (1 mM) potentiated in the effects of H₂S donor NaHS. Thus, the contractile activity of vascular smooth muscles in metabolic syndrome is determined by not only the effect of H₂S, but also the influence of NO.

Regulation of Vascular Smooth Muscle Contractions in the Model of Metabolic Syndrome

Reduced glucose tolerance, hyperglycemia, and imbalance in lipid levels were found in rats with metabolic syndrome induced by a high-fat, high-carbohydrate diet. The contractile responses of intact and endothelium-denuded aortic smooth muscle segments from rats with metabolic syndrome to application of acetylcholine, phenylephrine, sodium nitroprusside, and forskolin were studied by mechanographic method. It was found that endothelial dysfunction develops against the background of metabolic and hemodynamic disorders in metabolic syndrome. It was shown that the regulation of vasoconstrictor reactions of vascular smooth muscles in metabolic syndrome is due to a decrease in Ca²⁺ entry, mainly voltage-independent, as well as changes in the function of cGMP- and cAMP-activated K⁺-channels.

[Molecular Mechanisms of Action of Gas Transmitters NO, CO and H2S in Smooth Muscle Cells and Effect of NO-generating Compounds (Nitrates and Nitrites) on Average Life Expectancy]

Gaseous signaling molecules (gas transmitters) take an especial position among the numerous signaling molecules involved in the regulation of both intracellular processes that occur in different types of cells and cell-cell interactions. At present time, gas transmitters include three molecules whose enzymatic systems of synthesis and degradation, physiological action and intracellular effectors, the change of which under the action of gas transmitters may result in physiological and/or pathophysiological effects are well- determined. These molecules include nitrogen oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S). They are involved in the regulation of functions of various organs and systems of the human body, including the circulatory system. Interaction of NO, CO and H2S with various enzymatic and structural components of endothelial and, especially, smooth muscle cells has a significant impact on vascular tone and blood pressure. Furthermore, the crossing of NO-, CO- and H2S-mediated signaling pathways at common effectors and interaction with each other can determine the end, resulting functional response of the cell. The knowledge of the molecular targets of gas transmitters' action, the structure of the binding centers for gas transmitters and their interaction with each other may be essential in the development of methods of regulation of these signaling systems by targeted, directed action. This review summarizes the molecular mechanisms of the NO, CO and H2S interaction with the main targets, which carry out their regulatory effect on vascular smooth muscle cells. Also we describe here different ways of cross-regulation of NO-, CO- and H2S-dependent signaling pathways. We analyzed NO-synthase and nitrite reductase systems of nitric oxide cycle and discuss the nitrate-nitrite background of the existence of modern man, which can substantially modify the signaling system, the metabolism of virtually all cell ultrastructure of neurons, neuron-neuron and neuron-glial interactions and exerts its influence on socially significant diseases that can affect the quality and the average life expectancy.

Regulation of Contractile Responses of Vascular Smooth Muscle Cells under Conditions of Hypoxia-Reoxygenation

We analyzed the effects of hypoxia and reoxygenation on changes in contractile activity in rat aortic smooth muscles. Both hypoxia and reoxygenation induced relaxation of smooth muscle cells precontracted with high-potassium Krebs solution (30 mM KCl) or α₁-adrenoceptor agonist phenylephrine. Vasodilation resulted from enhancement of potassium permeability of smooth muscle cell membranes caused by activation of voltage-gated potassium channels (triggered by both precontracting agents) or by opening of ATP-sensitive potassium channels (phenylephrine). In isolated smooth muscle cells, both hypoxia and inhibition of Na⁺,K⁺-ATPase with ouabain led to depletion of intracellular store of macroergic substances, reduced potassium concentration, and elevated the content of sodium ions.

[THE INFLUENCE OF HYDROGEN SULFIDE ON COLLAGEN-INDUCED AGGREGATION OF HUMAN PLATELETS]

Study the impact of hydrogen sulfide on collagen-induced platelet aggregation from healthy donors and patients with type 2 diabetes. In healthy individuals, in contrast to patients with type 2 diabetes, NaHS significantly inhibited platelet aggregation. Activators of cAMP signaling (forskolin and phosphodiesterase inhibitor) significantly reduced platelet aggregation in both groups of examinees. NO-synthase inhibitors increased platelet aggregation in healthy volunteers, but not in patients with type 2 diabetes. The presence of H2S donor did not alter the extent of platelet aggregation at high concentrations of cAMP or decreased production of nitric oxide. It is assumed that the antiplatelet effect of H2S is not associated with the effect on the signal system, mediated cAMP or nitric oxide. Change H2S-dependent regulation of platelet aggregation in patients with type 2 diabetes is caused by disorders have been reported with this disease: the increase of intracellular calcium ion concentration, oxidative damage to proteins, hyperhomocysteinemia, glycosylation of key proteins involved in this process.

[Gas Signalling in Mammalian Cells]

At the end of the last century after the discovery of signaling functions of nitric oxide (NO, II), a new class of biologically active substances was admitted. It includes so-called gas transmitters acting as intercellular and intracellular regulators of different physiological functions. Currently, this class includes such gases as NO, carbon monoxide (CO) and hydrogen sulfide (H2S). It was found that these gases regulate not only functions of the. gastrointestinal tract and the cardiovascular system, where it has been determined initially, but also affect the function of the central and peripheral nervous.systems. Apparently, they constitute a single complex of gas transmitters, which easily penetrates through the membrane and regulates numerous enzymatic and non enzymatic cells reactions. This review presents the mechanisms of gas transmitters' influence on the electrical and contractile properties of smooth muscle cells (SMC) as a possible new ways to interact with the "classical" intracellular signaling cascades (Ca2+, cyclic nucleotides) and effectors systems. On account of their interactions the role of cyclic nucleotides and calcium ions in the implementation of the signal gas molecules functions is analyzed. We summarize the literature data and the results of our own research on the role of SMC membrane ion-transporting systems in myogenic effects of NO, CO and H2S and describe possible reasons of gas transmitters multidirectional influence on the excitation-contraction coupling in SMC.

[THE ROLE OF HYDROGEN SULFIDE IN VOLUME-DEPENDENT MECHANISMS OF REGULATION OF VASCULAR SMOOTH MUSCLE CELLS CONTRACTILE ACTIVITY]

The hydrogen sulfide (H2S) influence on the contractile activity of vascular smooth muscle cells (SMC) was studied on endothelium-denuded aortic ring segments of male Wistar rats with method of mechanography. Contractions of SMS were induced by incubation in high potassium solution as well as in hyper-, hypo- and isosmotic solutions. 5-100 LM of H2S donor--sodium hydrosulfide (NaHS) increased mechanical tension of SMC precontracted with high potassium solution that was abolished by bumetanide--the inhibitor of Na+, K+, 2Cl(-) -cotransporter (NKCC), but 100-1000 microM of NaHS relaxed SMS. NaHS (10 microM) increased the amplitude of hyper- and isosmotic contraction, but not of hyposmotic contraction. NaHS (ImM) decreased the amplitude of hyper-, iso-, and hyposmotic contractions. The direct measurements of NKCC activity with radionuclide method showed an increase in NKCC activity under the action of 5-100 microM of NaHS. These findings suggest that low concentrations of H2S participate in the NKCC activation. This mechanism underlines constrictive action of H2S on smooth muscle cells.

[In vitro study of the radial artery vasodilatory reactions]

The aim of the study was to investigate comparative contractility of isolated radial artery segments (n = 50). Phosphodiesterase inhibitor (papaverine) was used in 15 segments; dihydropyridine calcium channel antagonist (adalat) was used in 12 segments; calmodulin inhibitor (aminazine) was used in 13 segments; and "nitromixture" (5 mg verapamil hydrochloride, 2.5 mg nitroglycerine, 500-UN heparin, and 300 mL isosmotic Krebs solution) was used in 10 segments. Effect of hyposmotic solution for the morphometric properties of radial artery was analyzed in 22 arterial segments. The data didn't show statistical differences between drugs: "nitromixture" decreased tone by 100 ± 2% (n = 10), papaverine by 100 ± 11% (n = 15), adalat by 95 ± 6.1% (n = 12) and aminazine by 92 ± 11.3% (n = 13) (p > 0.05). The most effective drug in duration was adalat (n = 12, 90 ± 6.5 minutes) versus "nitromixture" (n = 10, 60 ± 9.3 minutes), papaverine (n = 15, 60 ± 4.3 minutes) and aminazine (n = 13, 50 ± 3.2 minutes) (p < 0.05).

[Research of cytoskeleton-dependent mechanisms of contractile activity regulation in the smooth muscles]

Influence of modulation of cytoskeleton by colchicine, vinblastine and cytochalasine B on contractile reactions of smooth muscles has been investigated by mechanographical method, by the methods of the double sucrose gup junction. Ratio F/G-actin in smooth muscle cells defined a method of a fluorescent microscopy. Microfilaments in a greater degree than microtubule are involved in regulation of reductions caused by hyperpotassic-induced reductions of membrane of smooth muscle segments of the rat aorta and generation of action potentials and reductions smooth muscle cells from guinea pig urethra. Reductions of vascular segments of aorta in rats caused by a hyperosmotic solution depend on condition of microfilaments and microtubules, whereas reductions in isoosmotic striction cells depend on condition of microfilaments. The last are involved in mechanisms of phenylephrine influence on mechanical strain of vascular segments of the rat aorta. Contrary to that, microtubules are involved in stimulation by phenylephrine electric and contractile activity the smooth muscle cells guinea pig urethra. Oppressiof contractile activity of smooth muscle segments of the rat aorta is cAMP-mediated and depends on condition of microfilaments of cytoskeleton, while action potentials and reductions smooth muscle cells of a ureter depend on condition of microtubules.

[Definition of parameters of the condition of oxidizing stress in smooth muscle cells under influence of exogenous nitroso-glutatyon in vitro]

Influence of exogenous nitroso-glutatyon on intensity of oxidizing processes in smooth muscles of colon and bronchial tubes in intact and atopic sensitised porpoises (guinea pigs) was studied. In sensitised porpoises, antioxidant protection has been initially reduced against the background of increased maintenance of products of oxidizing that reflects a picture of oxidizing damage and can be associated with an inflammatory process. In incubation with nitroso-glutatyon, a decrease in activities of syperoxiddismutase and catalase is marked and, in sensitised animals, this effect has been expressed to a lesser degree. Syperoxiddismutase and catalase are antioxidant for the enzymes participating in protection of cells from free-radical damage. A dose-dependence decrease in activity catalase and syperoxiddismutase is defined by a parity of the enzymes participating in disintegration of nitrosoglutatyon and the enzymes which have kept antioxidant activity.

[Na+,K+,2Cl(-)-cotransport and chloride permeability of the cell membrane in mezaton and histamine regulation of electrical and contractile activity in smooth muscle cells from the guinea pig ureter]

Influence of Na+,K+,2Cl(-)-cotransport and chloride permeability of the cell membrane on electrically-induced action potential and contraction of smooth muscle cells from guinea pig ureter was examined with the methods of the double sucrose gap junction. Mesatone (10 microM) and histamine (10 microM) induced prolongation of the action potential and elevation of smooth muscle cell contraction, whereas hyperosmic medium (+150 mM sucrose), and recovery of solution osmolality in hyposmic condition (70 mM NaCl) after a single contraction. Inhibitor Na+,K+,2Cl(-)-cotransport bumetanide (10 microM) and chloride permeability blockers niflumic acid (10-100 microM) and SITS (10-500 microM) attenuated stimulating effects of mesatone, histamine and hyperosmic medium. In opposite to adenylate cyclase activation with forskolin (1 microM), guanylate cyclase activation with sodium nitroprusside (SN, 100 microM) decreased both inhibitory action of bumetanide, niflumic acid and activating effects of mesatone, histamine on action potential and elevation contraction of smooth muscle cells. Influence of forskolin rather and not SN on AP and SMC C was inhibited with tetraethylammonium (5 mM). These results suggest that influence of Na+,K+,2Cl(-)-cotransport on electrical and contractil properties of ureter smooth muscle cells is mediated by stimulation of Ca(2+)-activated chloride permeability of the cell membrane and modulated by intracellular cGMP, but not triggered by Ca2+ release from sarcoplasmic reticulum.

[Features of the pharmacosensitivity of smooth muscles of the lesser circulation circle artery walls in rabbits]

Features of the pharmacological sensitivity of smooth muscles in the walls of arteries of the lesser circulation circle in rabbits with respect to cholinergic, histaminergic, and adrenergic agents, as well as the influence of endothelium on the realization of contractile response to these agents have been investigated in rabbits. A special feature in the cholinergic relaxation of smooth muscles of a pulmonary artery is a two-componential character of the dose dependence. The low-threshold component of the relaxant action of pilocarpine exhibits the endothelium-dependent character. An important feature of the contractile reaction to histaminergic action is a direct contractile effect of histamine, which is not observed in vessels of the greater circulation circle. Endothelium produces an inhibiting effect on the histaminergic contractility. The basic feature in the response to adrenergic action is the beta-adrenergic contractility effect. Activation of the cAMP-dependent alarm system in smooth muscles of the pulmonary arteries leads to a constrictive effect. The established features of the pharmacological sensitivity of smooth muscles of the artery walls of the lesser circulation circle are important for the clinical pharmacology.

[Physiological characteristics of the smooth muscles vessels of the small circle of blood circulation]

Now sireos problem of pulmonology there are the diseases connected with infringement of coordinated regulation of a tone of smooth muscles of vessels and airways of ways that conducts to dissociation of parameters haemodinamyc and ventilation of lungs and as consequence, to infringement airwave-perfusion attitudes. In the review features humoral regulation contractile activity of smooth muscles of vessels of a small circle of blood circulation, a role of endocellular alarm systems in these mechanisms, and endothelium, as the local modulator endocrine functions are considered. Disgusting muscles of a small circle are distinguished from the main vessels of the big circle of blood circulation with predisposition to the raised mechanical pressure. In spite of the fact that endothelium renders modulating relaxe influence on contractile answers of smooth muscles of vessels of a venous and arterial small circle of blood circulation at action corresponding vasoconstriction, pulmonary veins are capable to endothelium-dependent dilatation to a lesser degree, in comparison with pulmonary arteries. And, on the contrary, in absence endothelium, they are characterized with high sensitivity to vasopression to substances--serotonin, histamine, phenylephrine. Features of regulation smooth muscle pressure pulmonary an artery are shown in contractile reactions of its isolated segments in reply to influence beta-adreno agonist--isoprotherenol and phosphoesterase inhibitors. Though, increase in endocellular concentration cyclic nucleotides (cAMP and\or cGMP), on the standard representations, cannot explain growth of a mechanical pressure of smooth muscles, apparently, in contractile reactions of a pulmonary artery to influence biologically and physiologically active substances interfere more complex mechanisms in which basis processes of interaction of smooth muscles cells lay, endothelium and cells of a microenvironment. Finding-out of the contribution cyclic nucleotides in these processes demands the further researches.

Effect of Na+,K+,2Cl- cotransport inhibitor bumetanide on electrical and contractile activity of smooth muscle cells in guinea pig ureter

The effect of Na(+),K(+),2Cl(-) cotransport inhibitor bumetanide on action potentials and contractions of smooth muscle cells in the ureter of guinea pigs evoked by electrical stimulation was studied by the method of double sucrose bridge. Bumetanide (10-100 microM) dose-dependently suppressed action potential and contractions of smooth muscle cells induced by 1-10 microM histamine, 10 microM mesatone, 5 mM tetraethylammonium, and 100 microM sodium nitroprusside. Our findings suggest that test substances modulate Na(+),K(+),2Cl(-) cotransport in smooth muscle cells.

[The mechanisms in NO-dependent regulation of electrical and mechanical activity in smooth muscles]

The role of nitric oxide (NO) and its implication in intracellular and intercellular signaling pathways attract an attention of many research teams up to now. Away of its signaling functions. NO is considered as one of the key molecules in maintenance of balance between the physiological and pathological processes due to cytoprotective and cytotoxic functions of this molecule. In this regard, elucidation of the NO-dependent mechanisms, involved into the physiological processes and pathophysiological reactions, remains an urgent problem of conntemporary biology and medicine. Analysis of obtained results establishes a relative contribution of electro- and pharmaco-mechanical coupling mechanisms in NO-dependent regulation of smooth muscle cels (SMC) functions. The authors show that elevation of intracellular Ca2+ concentration by biologically active substances promotes relaxing effect of NO through both voltage-dependent and -independent intracellular mechanisms of calcium redistribution. Namely the peculiarities of considered mechanisms in each certain type of SMCs cause the final direction of alterations in contractility and membrane potential. It has been shown that voltage-dependent effects of NO are mediated by suppression of calcium and/or sodium components and modulation of Ca2+ -dependent and ATP-seisitive potassium components of SMC membrane permeability, Voltage-independent NO control of mechanical smooth muscles activity mainly is mediated by 1) modulation of protein kinase C (PK-C) branch of calcium signaling system, 2) ratio of cyclic nucleotides intracellular concentrations (cGMP/cAMP), and 3) directional mode of electrosilent Na+, K+, 2Cl- -cotransport. Our results show that the features of the myogenic effects of NO are caused by the peculiarities of PK-C operation in SMC.

[Demographic problems and reproductive health of women and children of first year of life]

The authors presented comparative evaluation of general demographic situation and reproductive health of women and infants in main mining and industrial districts of Mourmansk region.

[Neoplasm mortality in population residing near extracting and processing apatite ore facilities]

Increased mortality with malignancies in population who reside near enterprises processing Kolsky apatite-nepheline ores is determined mostly by mortality among an "occupational group" engaged into this production.

[Studying cGMP-dependent mechanisms of vinpocetine effect on smooth muscle cells]

The results of the membrane potential measurements (by the double sucrose gap junction technique) and the smooth muscle tension determination (by the mechanical force measurements) in the rat aorta showed that vinpocetine potentiates the effect of sodium nitroprusside and nitroglycerin on the smooth muscle cells. In the concentration range of 2-20 microM, vinpocetine produced a dose-dependent inhibition of the Ca2+ conductivity of the membrane and decreased the smooth muscle contractility response. At a concentration of 1 microM, the drug acted as an inhibitor of the phosphodiestherase (PDE) activity and produced the effects similar top those of dibutyryl-cGMP (rather than dibutyryl-cAMP). In the presence of 10 microM of Methylene Blue (an inhibitor of the soluble fraction of guanylate cyclase), the cGMP-dependent effects of vinpocetine were suppressed on the background of 100 microM of sodium nitroprusside, but retained on the background of 10 microM of 3-isobutyl-1-methylxanthine (IBMX), a nonspecific PDE inhibitor. IBMX acted like dibityryl-cGMP and activated the K+ conductivity of the membrane. It is suggested that cGMP-dependent effects of vinpocetine are related to its action upon the Ca2+ and Na+ and (but not K+) conductivity and to the cGMP-induced increase in the contribution of sarcoplasmic calcium to the contractile response.

Role of cyclic nucleotides in regulation of pulmonary artery tone in rabbits

The involvement of cAMP- and cGMP-dependent signal systems into the regulation of the contractile reaction of smooth muscles of the rabbit pulmonary arteries was studied using a mechanographic method. For modulation of intracellular level of cyclic nucleotides we used adenylate cyclase activators beta-adrenoceptor agonist isadrin, guanylate cyclase inhibitor methylene blue, penetrating analog dibutyryl-cAMP, and phosphodiesterase inhibitors. The mechanisms of cAMP- and cGMP-dependent regulation of smooth muscle contractile activity were realized in close interrelationship, and the key component of this was cyclic nucleotide phosphodiesterases. The ratio of activities of phosphodiesterase subtypes in smooth-muscle cells can essentially modulate the adrenergic effects in the pulmonary artery wall and even invert them.

[Myogenic effects of cyclic guanosine monophosphate in smooth muscle cells. Role of protein kinase C]

Heterogeneity of the cGMP-dependent contractility effects of the smooth cells (SMC) was shown in guinea pig ureter by the methods of the double sucrose gap junction. Sodium nitroprusside (SN, 0.1-100 microM) relaxed the high-K+ depolarisationprecontracted SMC but strengthened the SMC constriction triggered by electrical stimulation. In taenia coli, SN or nitroglycerin in the same concentration ranges depressed the electrical or mechanical activity of the SMC and relaxed the SMC, precontracted by depolarization in high-K+ medium. The inhibitor of the phosphodiesterases vinpocetine (1 microM) contributed to the activating effect of SN; the inhibitor of the soluble guanilatcyclase Methilen Blue (10 microM) depressed it. Histamine and mesotone (1-10 microM) increased the action potential and constriction of the SMC triggered by electrical stimulation but decreased the effect of SN. The activator of the protein kinase C (PK-C) phorbol miristoyl-13-acetyl (0.5 microM) changed direction of the SN effects inhibiting both the parameters of an action potential and of the SMC constriction. The pre-treatment with the inhibitor of PK-C calphostin C (0.1 microM) additionally depressed the effects of SN, increasing SMC constriction, especially in the presence of histamine and mesatone. We suggest that c-GMP depressed activity of the PK-C by independent mechanisms operating in SMC.

[Regulation of smooth muscles of the vascular wall in the rabbit pulmonary artery]

The cholinergic, histaminergic and adrenergic features of regulation of the small muscles contractile activity in a vascular wall of a pulmonary artery in rabbits and involvement of an endothelium in these processes, were investigated. The cholinergic release phenomenon of small muscles of the rabbit pulmonary artery has a two-component character of dose dependence. The low-threshold components of Pilocarpinum relaxing effect has an endothelium-dependent nature. The important feature of histaminergic regulation of contractile activity of segments involves a direct contractile effect of histamine that is not inherent. The endothelium renders a suppressing effect on histaminergic contraction of small muscles of the rabbit pulmonary artery. A basic feature of adrenergic regulation of the pulmonary artery involves registered-beta-adrenergic contractile effects in small muscles of a vascular wall. The activation of the cAMP-dependent signal system in small muscles of a pulmonary artery is capable of rendering a contractile effect. The detected features of a regulation in the small circle can have an essential clinical-physiological value.

Peculiarities of adrenergic regulation of smooth muscles in rabbit pulmonary arteries

Muscle tension recording was used to study adrenergic contractile reactions of pulmonary artery smooth muscles in rabbits. Stimulation of alpha-adrenoceptors induced contraction of pulmonary artery smooth muscle cells. Endothelium partially inhibited the contractile effect of alpha-adrenoceptor agonists. Activation of smooth muscle beta-adrenoceptors in pulmonary arteries produced a dual dose-dependent effect (relaxation at agonist concentrations of 10 nM-1 muM and contraction at concentrations above 10 muM). The contractile effect of beta-adrenoceptor activation in smooth muscle cells is a specific feature of pulmonary arteries probably related to peculiarities of cAMP-signaling in these cells.

Effect of inhibitors of cyclic nucleotide phosphodiesterases on electrical and contractile activity of smooth muscle cells

Double sucrose gap experiments were carried out to study the effect of phosphodiesterase inhibitors and penetrating analogs of cyclic nucleotides on action potential and contraction of guinea pig ureteral smooth muscle cells. 3-Isobutyl-1-methylxanthine (10 microM) and dibutyryl-cAMP (20 microM) shortened the plateau of action potential and inhibited contraction of smooth muscle cells by increasing potassium permeability of their membrane. Vinpocetine (1 microM) and dibutyryl-cAMP (100 microM) strengthened contraction of smooth muscle cells and shortened action potentials by decreasing sodium permeability of their membrane.

Histaminergic regulation of smooth muscles in rabbit pulmonary arteries

Histaminergic contractile reactions of smooth muscles in rabbit lobar pulmonary arteries were studied using in vitro mechanographic technique. Histamine via activation of H-receptors induced a dose-dependent constriction of smooth muscle segments, while endothelium inhibited histamine-induced contractile reactions. Histamine increased sensitivity of smooth muscle cells in pulmonary artery to sodium nitroprusside.

[Mechanisms of NO-dependent relaxation in smooth muscles of the rat aorta with nitro compounds]

The membrane potential and smooth muscle tension in rat aorta were studied by the method of sucrose gap junction. It was found that sodium nitroprusside and nitroglycerin produced a dose-dependent membrane repolarization and smooth muscle cell relaxation in rat aorta preliminarily contracted and depolarized by hyperpotassium (40 mM) or phenylephrine solutions. The relaxation effect of sodium nitroprusside was more pronounced on the phenylephrine background. The effect of nitroglycerin showed a different kinetics in time and led to the tolerance development. The effects of both nitro compounds were inhibited by pretreatment with Methylene Blue or potassium channel blockers. It is suggested that nitro vasodilators are involved in the NO-dependent processes in smooth muscle cells of aorta through cGMP-mediated activation of the potassium conductivity and by changing the efficiency of operation of the protein kinase C branch of the Ca2+ signal system.

[Disruption of microbiocenosis of the large intestine and the immune and interferon status in children with bacterial complications of acute viral infections of the respiratory tract and their correction by high doses of bifidumbacterin forte]

One hundred and twenty-nine children with acute viral and bacterial infection of the respiratory tract were examined and disturbance of the large intestine microflora was detected. It was characterized by significant reduction of lactobacilli, moderate growth of opportunistic bacteria and higher contents of Candida. Changes in T- and especially B-cellular immunity were observed in 35 per cent of the patients. In patients with decreased avidity of the immunoglobulins G in the peripheral blood the changes were observed in 82-100 per cent of the cases. In the majority of the patients the capacity for interferon genesis was suppressed. A shorten course (5 days) of the bifidumbacterin forte therapy in a dose of not less than 10(9) CFU/ml. normalized the intestinal microflora, improved the indices of the B- and T-cellular immunity (including the subpopulation of the T-helper cells but not the T-suppressor cells), stimulated NK and improved the ability to induce alfa- and gamma-interferons of the peripheral blood leukocytes. The experience with using high doses of bifidumbacterin forte was evident of its good tolerance and possible value in increasing the patient resistance to infection.

[Intracellular signal systems in the epithelium- and endothelium-dependent relaxation of smooth muscles]

The research of mechanisms of a regulation electrical and contractile of properties of unstriated muscles of an internals remains by an actual problem of modern physiology and medicine. Already now it is possible to state that the efficacy of means of correction of distresses of an internals depends on a degree of a level of scrutiny of these mechanisms. Among physiologically active substances effecting on smooth muscle cells (SM), the special relaxing factor synthesized by endotheliocytes, epithelial cells and SM. Identified by the majority of the explorers as oxide of nitrogen (NO), relaxing factor responds for exhibiting of many myogenic responses of pots and pneumatic routes. The mechanisms of synthesis and implementation of effects of this factor in SM cells up to the extremity are not clarified. The considerable advance in learning mechanisms of operation relaxing factor on SM is connected to discovering of ability of some nitro compounds to replicate NO-dependent relaxing effects in these cells. The main systems of intracellular regulation are involved in mechanisms of implementation endothelial and epithelial local regulatory effects on SM. The majority of the explorers bind an epithelium-dependent release phenomenon SM to an activation of a solvable fraction guanilatcyclase, found in the majority of cells, and effects of cGMP-dependent protein kinases. There are reports on ability of inhibitors NO-sintase to depress a release phenomenon SM of pots and bronchuses, about dependence of a mechanical strain SM of pots and respiratory tract from a contents cGMP in cells. However there are datas giving establishments to guess, that alongside with guanilatciclase in a release phenomenon SM, induced relaxing factors or nitro compounds, the immediate involvement is accepted by cAMP-dependent protein kinases. The most probable point of interaction cAMP and cGMP-dependent processes is phospodiesterase of cyclic nucleotides. It citosolium the enzyme labilized by calmodulin, is capable to carry out a hydrolysis of both cyclic nucleotides, and the affinity native phospodiesterase to cGMP exceeds affinity to cAMP more, than on the order. It is impossible to eliminate immediate interference of NO-dependent processes in a regulation of activity contractile proteins. The ability cGMP-dependent processes to depressing mechanisms of phosphorylation and intensifying of a dephosphorylization of contraktion proteins SM is shown. At these processes can variate and affinity of the acto-miosin complex to ions of calcium, producing a release phenomenon of smooth muscles. On all visibility, production relaxing of the factor and the implementation is epithelial and endothelium-SM of mutual relation in a respiratory tract and pots comes true by modulating influence at the calcium signal system of other systems. For example, production relaxing of the factor by an epithelium and endothelium, being calcium-dependent process, is regulated at involvement calmodulin-similar Ca(2+)-connecting proteins and protein kinase C. Control of tone SM through change of membrane potential relaxing factor carries out by paravariation of potassium conduction of a membrane SM, and, is more probable than all through calcium-dependent and ATP-sensitive components. Potencial-dependent control of a muscle tone comes true through change of efficacy of an operation from a branch of the calcium signal system and calcium pompes at submaximal concentrations of free calcium in citosolium.

Peculiarities of cholinergic regulation of smooth muscles in rabbit pulmonary arteries

Cholinergic contractile reactions of smooth muscles in rabbit pulmonary arteries were studied by mechanography. The muscarinic receptor agonist pilocarpine induced biphasic relaxation of mesatone- or potassium-precontracted segments from lobar pulmonary arteries with intact endothelium. The low-threshold endothelium-dependent component of pilocarpine-induced relaxation was suppressed by denudation or nitric oxide synthase blocker L-NAME.

Effect of nitro derivatives on electromechanical coupling in ureteral smooth muscle cells

Double sucrose gap experiments revealed differences in the effect of nitroglycerin and sodium nitroprusside on action potential and contraction of ureteral smooth muscle cells. Unlike sodium nitroprusside, nitroglycerin inhibited voltage-dependent Ca(2+) membrane permeability. It was concluded that cGMP-independent mechanisms of the effects of nitro derivative reflect the peculiarities of excitation-contraction coupling in smooth muscles.

[The role of sodium-proton exchange in the regulation of the electric and contractile activity of smooth muscles]

The Na+/H+-exchange inhibitor aethylisopropylamyloride was found to enhance the membrane resistance, the AP duration, and the duration of the guinea pig ureter's smooth muscle contraction. Tetraethylammonium and incubation in the Ca-free EG-TA-containing solution eliminated the activating effect of this inhibitor. Gramycidin A shortens the AP plateau. The Na+/H+-exchange mechanism seems to act under normal conditions. Alterations occurring in electrical and contractile activities of smooth muscle under the effect of the Na+/H+-exchange seem to result from the changes in the membrane Ca-dependent potassium conductivity.

[The effect of sodium nitroprusside on the membrane potential and mechanical tension of the smooth-muscle cells in the rat aorta]

The rat aorta smooth muscles were contracted and depolarised with high potassium or phenylephrin solution which was followed by a relaxation and repolarisation after sodium nitroprusside administration. The latter effect was decreased az a combined action of phenylephrin and high potassium solution. Nitroprusside seems to act through a cGMP-dependent potassium transient activation of the smooth muscle cell membrane.

[Epithelial-smooth muscle interaction in the regulation of the tonus of the airways in rats]

The rat trachea epithelium was found to affect a catecholamine-induced relaxation of the trachea smooth muscles, to release a relaxing factor, the producing of which depends on calcium and is regulated by calmoduline and proteinkinase C. The epithelium-induced relaxation seems to depend on the animal age.