[The effect of ATP-dependent K(+)-channel opener on transmembrane potassium exchange and reactive oxygen species production upon the opening of mitochondrial pore].

The effect of mitochondrial ATP-dependent K(+)-channel (K(+)ATP-channel) opener diazoxide (DZ) on transmembrane potassium exchange and reactive oxygen species (ROS) formation under the opening of mitochondrial permeability transition pore (MPTP) was studied in rat liver mitochondria. The activation of K(+)-cycling (K(+)-uptake and K(+)/H(+)-exchange) by DZ was established with peak effect at < or = 500 nM. It was shown that MPTP opening as well resulted in the activation of K(+)-cycling together with simultaneous activation of Ca(2+)-cycle in mitochondria. In the absence of depolarization Ca(2+)-cycle is supported by MPTP and Ca(2+)-uniporter. The stimulation of K(+)/H(+)-exchange by MPTP opening led to the activation of K(+)-cycle, but further activation of K(+)/H(+)-exchange resulted in MPTP inhibition. Under the same conditions the decrease in mitochondrial ROS production was observed. It was proposed that the decrease in ROS formation together with K(+)/H(+)-exchange activation could be the constituents of the complex effect of MPTP inhibition induced by K(+)ATP-channel opener.

[The effect of ATP-dependent K(+)-channel opener on the functional state and the opening of cyclosporine-sensitive pore in rat liver mitochondria].

The effect of mitochondrial ATP-dependent K(+)-channel (K+(ATP)-channel) opener diazoxide (DZ) on the oxygen consumption, functional state and the opening of cyclosporine-sensitive pore in the rat liver mitochondria has been studied. It has been established that K+(ATP)-channel activation results in the increase of the oxygen consumption rate (V4(s)) and the uncoupling due to the acceleration of K(+)-cycling, the decrease in state 3 respiration rate (V3) and the respiratory control ratio (RCR). Under K+(ATP)-channel activation an inhibition of oxidative phosphorylation takes place which reduces the rate of ATP synthesis and hydrolysis as well as ATP production and consequently results in the seeming increase of P/O ratio. It has been shown that the increase in ATP-dependent K(+)-uptake accompanied by the opening of mitochondrial permeability transition pore (MPTP) leads to dramatic uncoupling of the respiratory chain due to simultaneous activation of K(+)- and Ca(2+)-cycling supported by MPTP and Ca(2+)-uniporter as well as K(+)-channels and K+/H(+)-exchange. K+(ATP)-channel activation leads to the partial inhibition of MPTP, but insufficient for the restoration of mitochondrial functions. Elimination of Ca(2+)-cycling after MPTP opening is necessary to return mitochondrial functions back to the control level which shows that MPTP could serve as the mechanism of reversible modulation of bioenergetic effects of K+(ATP)-channel activation.

[Effects of modulators of calcium metabolism on mesenteric artery contractions during activation of P2X receptors in guinea-pig].

ATP evokes changes in the vascular tone through the activation of P2X and P2Y purinoceptors. To evaluate relative contribution of Ca2+ entry through the L-type voltage-gated calcium channels and Ca2+ -induced Ca2+ -release (CICR) mechanisms in initiation of vascular smooth muscle contraction induced by P2XRs activation, we have applied P2X receptor agonist -meATP (10 microM) and measured changes in phasic isometric tension of endothelium-denuded mesenteric artery rings in the presence of antagonists IP3Rs (60 mcmol/l APB) or RyRs (100 mcmol/l tetracaine) combined with on-off modulation of the L-type calcium channels by nicardipine (5 microM). We found that activation of P2XRs results in Ca2+ release from SR through both IP3Rs and RyRs. In addition, Ca2+ entry via L-type Ca2+ channels also participates in Ca2+ release from SR presumably through CICR mechanism. However, the phasic contractions in the presence of nicardipine were found to be less sensitive to inhibition of IP3Rs than RyRs (47.1 +/- 9.5% and 22.9 +/- 1.4% comparing to 38.3 +/- 9.6% and 518 +/- 7.8% in control solution for IP3R and RyR inhibition, respectively). This finding suggests that Ca2+ entered the cell through L-type Ca2+ channels, has easier access to IP3Rs than to RyRs. This suggestion is further supported by immunostaining IP3Rs and RyRs. Confocal imaging revealed that sub-PM SR elements are enriched with IP3Rs, while RyRs are predominantly located in the central/perinuclear SR elements.

[The treatment of neurospastic vascular diseases in Raynaud phenomenon].

The efficacy of proposed methods for cardiovascular diseases with Raynaud phenomenon manifestations treatment was estimated. After application of the author method the patients extremities temperature had raised by 2 .50 degreesC. They had noted the pain and the extremities oedema elimination, trophic ulcers healing. According to Doppler investigation data the blood flow linear speed increase by 30 0% in comparison with pretreatment one was noted. The posttreatment complications were absent. Fair and good results were observed in 306 (82.3%) patients, in 21 (5.6%) patients the treatment was repeated in conditions of severe ischemia and the blood flow decompensation present. In 14 (3.8%) patients a high epidural blockade of sympathic nodes in portion of high thoracic and lower cervical vertebra according to the author method was performed. In far-remote period (in 3-10 years) the positive effect was prolonged in 298 (80.1%) patients.

[Involvement of voltge dependent potassium channels in rabbit corpus cavernosum responses to oxidative stress].

Previously we have demonstrated that oxidative stress produces a complex response of the rabbit corporal smooth muscle cells consisting of transient relaxation followed by contraction. We used 4-AP and TEA, selective blockers for voltage- and Ca(2+)-dependent K+ channels to investigate possible contribution of these channels in maintaining of basal cavernosal tone as well as in mediating of contractile response caused by oxidative stress. TEA in concentration of 1 mmol/l caused contraction of corporal smooth muscle. Application of hydrogen peroxide (H2O2) in the presence of TEA caused contraction similar to that in control conditions. This argues against involvement of Ca(2+)-dependent K+ channels in contractile response caused by oxidative stress. On the other hand, contractile response on inhibition of Ca(2+)-dependent K+ channels suggests their contribution in maintaining of corporal tone. 4-AP in concentration of 5 mmol/l caused contraction resembling that, evoked by TEA. Thus, voltage-dependent similar to Ca(2+)-dependent K+ channels contribute to corporal tone. In the presence of 4-AP H2O2 induced contraction was essentially decreased. The most probable explanation of this result is that population of channels modulated by 4-AP and H2O2 is common for both factors. We previously reported that H2O2 induced contraction could be inhibited by indometacine. Together these results suggest, that H2O2 induced contraction could be a result of inhibition of 4-AP-sensitive voltage-dependent K+ channels that is mediated by metabolite products of arachinoide acid via cyclooxigenase pathway.

[Role of nitric oxide in the corpus cavernosum reactions evoked by hydrogen peroxide]. / Rol' oksydu azotu v reaktsiiakh pecherystykh til, iaki vyklykani perekysom vodniu.

Corpus cavernosum smooth muscle spends the majority of its time in the contracted state consisting of tonic and tetanic components. Tetanic component is a result of superposition of phasic contrations ocuring spontaneously with a frequency of 5-27/minute. Hydrogen peroxide (H2O2) in concentration of 10(-3) mol/l causes a transient increase in tetanic contraction lasting 5 to 8 minutes, followed by either recovery of spontaneous activity or inhibition of its frequency and muscle strip relaxation. 30 minutes pretreatment with the specific blocker of NO syntase, L-NAME, does not affect the intrinsic spontaneous activity parameters but enhances H2O2 evoked reaction, increasing both the amplitude and duration of the transient contraction by 41.2 +/- 14.5 and 52.5% +/- 22.8% (n=9) correspondingly. By contrast, the exogenous NO donors nitroglycerin and sodium nitroprusside, cause spontaneous activity inhibition and muscle strip relaxation resulting in the decrease of H2O2 evoked contraction and duration by 8.7 +/- 3.7 and 24.5% +/- 10.6% (n=7) correspondingly. These results suggest that tetanic contraction is an important component of corpus cavernosum smooth muscle tone which is modulated by free radical oxygen species and controlled by NO dependent mechanism.

[Cholera in the Far East of Russia. Communication 2. Epidemiological characteristics of the outbreak of cholera El tor in Iuzhno-Sakhalinsk]. / Kholera na Dal'nem Vostoke Rossii. Soopshchenie 2. Epidemiologicheskaia kharakteristika vspyshki kholery él'tor v g. Iuzhno-Sakhalinske.

The outbreak of cholera eltor in Yuzhno-Sakhalinsk has been analyzed. The fact of the import of this infection from China and its transmission mainly by the water route due to the intensive contamination of environmental objects has been substantiated. The effective purification decontamination of sewage water plays decisive role on the system of anticholera measures. The conclusion on the necessity of increasing the effectiveness of measures for the sanitary protection of the territory has been made.

[Mechanisms of enhanced vascular contractility in experimental animals and humans in atherosclerosis]. / Mekhanismy posylenoï sudynnoï skorotlyvosti u eksperymental'nykh tvaryn i liudyny pry aterosklerozi.

Contractile and electrical responses of muscle strips from rabbit aorta to 5-HT and hyper K solution were compared in controls group of rabbits fed a normal diet, and atherosclerotic animals fed 1% cholesterol diet for 12 weeks (atherosclerotic group). A study of vascular responses of human popliteal artery was also carried out. It was shown that smooth muscle cells from arteriosclerotic vessels of both rabbits and human exhibit an increased sensitivity to contractile action of hyperpotassium solution and 5-HT. We found no significant difference in the densities of L-type Ca2+ channel current as well as voltage dependent K+ channels current measured by patch clamp method in single smooth muscle cells from control and atherosclerotic rabbit aorta. Removal of endothelium from the vascular strips resulted in an enhanced vascular contractility in control but not in atherosclerotic group. The dose response curves for endothelium-free muscle strips for both 5-HT and hyper K solution were not significantly different between the two groups. Our result suggest that the enhanced vascular responses to 5-HT and hyper K under condition of arteriosclerosis could be attributed to an impaired function of endothelium which is a source of substances particularly nitric oxide that mediates vascular relaxation and provides a compensatory mechanism to keep peripheral resistance at lower level.

The action of calcium channel blockers on recombinant L-type calcium channel alpha1-subunits.

1. CHO cells expressing the alpha(1C-a) subunit (cardiac isoform) and the alpha(1C-b) subunit (vascular isoform) of the voltage-dependent L-type Ca2+ channel were used to investigate whether tissue selectivity of Ca2+ channel blockers could be related to different affinities for alpha1C isoforms. 2. Inward current evoked by the transfected alpha1 subunit was recorded by the patch-clamp technique in the whole-cell configuration. 3. Neutral dihydropyridines (nifedipine, nisoldipine, (+)-PN200-110) were more potent inhibitors of alpha(1C-)b-subunit than of alpha(1C-a)-subunit. This difference was more marked at a holding potential of -100 mV than at -50 mV. SDZ 207-180 (an ionized dihydropyridine) exhibited the same potency on the two isoforms. 4. Pinaverium (ionized non-dihydropyridine derivative) was 2 and 4 fold more potent on alpha(1C-a) than on alpha(1C-b) subunit at Vh of -100 mV and -50 mV, respectively. Effects of verapamil were identical on the two isoforms at both voltages. 5. [3H]-(+)-PN 200-110 binding experiments showed that neutral dihydropyridines had a higher affinity for the alpha(1C-b) than for the alpha(1C-a) subunit. SDZ 207-180 had the same affinity for the two isoforms and pinaverium had a higher affinity for the alpha(1C-a) subunit than for the alpha(1C-b) subunit. 6. These results indicate marked differences among Ca2+ channel blockers in their selectivity for the alpha(1C-a) and alpha(1C-b) subunits of the Ca2+ channel.

[The results of combined surgical treatment of the occlusive forms of the deep vein thrombosis with the trophic ulcers in the lower extremities]. / Rezul'taty kompleksnoho khirurhichnoho likuvannia okliuziinykh form trombozu hlubokykh ven z trofichnymy vyrazkamy nyzhnikh kintsivok.

The results of treatment of 156 patients with occlusion forms of the deep veins thrombosis of the lower extremities and trophic ulcers are adduced. The partial or complete thrombectomy the shunting, Linton and Cockett operations, plastic interventions, the pulmonary artery embolism prophylaxis were conducted, and the late terms--the vibro- and hydromassage.

Evidence for a direct interaction of thapsigargin with voltage-dependent Ca2+ channel.

The effect of thapsigargin, an inhibitor of the sarco-endoplasmic reticulum Ca(2+)-ATPase, on voltage-dependent Ca2+ channels has been investigated in the A7r5 cell line and in membrane preparations from rat aorta, heart and brain. Patch-clamp technique showed that, at micromolar concentrations, thapsigargin inhibited the L-type Ca2+ channel current in A7r5 cells. It depressed the current at all voltages without change in the steady state inactivation curve. The rates of inactivation of the Ca2+ current were highly variable among the cells suggesting that more than one component of L-type Ca2+ current coexist in A7r5 cells, differing in the kinetics of inactivation. Thapsigargin appeared to be more potent on the slower-inactivating Ca2+ current than on the faster-inactivating one. In the same range of concentrations, thapsigargin inhibited the specific binding of 3H(+)-isradipine in intact cells while 45Ca2+ uptake in intracellular stores of skinned cells was inhibited at nanomolar concentrations. The equilibrium dissociation constant of 3H(+)-isradipine was increased in the presence of thapsigargin as a result of an increase of the dissociation rate constant indicating that the inhibitory effect of the antagonist cannot be attributed to a simple competitive interaction with the dihydropyridine binding site. Maximum binding capacity was unaffected. A similar pattern of inhibition of 3H(+)-isradipine binding was observed in membrane preparations from rat aorta, heart and brain. Those results indicate that, at micromolar concentrations, thapsigargin inhibits the voltage-dependent Ca2+ current by a direct interaction with the L-type Ca2+ channels.

[Effects of the membrane potential level on serotonin-induced contraction of the pulmonary artery smooth muscle in rabbits]. / Vliianie urovnia membrannogo potentsiala na vyzyvaemye serotoninom sokrashcheniia gladkikh myshts legochnoi arterii krolika.

The effects of changes in membrane potential level on the electrical and contractile responses induced by serotonin (10(-6) mol/l) were investigated in muscle strips from rabbit main pulmonary artery using sucrose-gap technique. In spite of the fact that serotonin-induced depolarization did not exceed the threshold level for development of contraction, it was followed by a strong tonic contraction. Nearly a half of this contraction could be relaxed by an electrotonic hyperpolarization of the membrane. A week preliminary depolarization of the muscle cells resulted in an increase while a strong depolarization--in dramatic decrease of serotonin-induced contraction. Nifedipine effectively blocked potassium-induced, but not serotonin induced contraction. We suggest that in addition to voltage-operated and receptor operated Ca channels in vascular smooth muscle cell membrane there is a separate class of nifedipine-insensitive Ca channels operated by both serotonin receptor and membrane potential.

[The role of calcium and potassium conductance in electrogenesis of smooth-muscle cells of the basilar artery]. / Rol' kal'tsievoi i kalievoi provodimostei v elektrogeneze gladkomyshechnykh kletok osnovnoi arterii.

The role of calcium and potassium conductances in electrogenesis of smooth muscle cells of the bovine basilar artery has been investigated using blocking agents of calcium and potassium channels both in the normal Krebs solution and in hyperpotassium solution under anelectrotonic repolarization of the cell membrane. It is shown that both voltage-operated calcium and potassium conductances participate in generation of gradual action potentials evoked by electrical stimulation. A higher contribution of potassium conductance into the total membrane conductance during depolarization is found to be the main factor interfered with development of full-size action potential.

[The role of intra- and extracellular Ca in the activation of contraction of pulmonary artery smooth muscles induced by serotonin]. / Rol' vnutri- i vnekletochnogo Ca v aktivatsii sokrashcheniia gladkikh myshts legochnoi arterii, vyzyvaemogo serotoninom.

In Ca-free EGTA-containing solution serotonin induced a transient contraction of rabbit pulmonary artery smooth muscle which decayed to nearly steady-state level accounted for 17.7 +/- 1.6% of original contraction in Krebs solution. Both phasic and tonic components of this contraction were effectively inhibited by verapamil and Cd2+. Caffeine induced no contraction of muscle strips if it was applied after withdrawal of serotonin. But when the sequence of these drugs application was reversed, serotonin still evoked contraction with reduced phasic component. The results obtained in these experiments suggest, that serotonin-induced contraction of pulmonary artery smooth muscle is partly (less than 20%) due to mobilization of bound calcium from at least two stores located on the opposite sides of the cell membrane. Calcium released from external store site enters the cell via receptor-operated calcium channels.

[Membrane mechanisms of the excitatory action of serotonin on the smooth muscles of the rabbit pulmonary artery]. / Issledovanie membrannykh mekhanizmov vozbuzhdaiushchego deistviia serotonina na gladkie myshtsy legochnoi arterii krolika.

Serotonin induced dose-dependent tonic contractions of the rabbit pulmonary artery smooth muscles with KED50, of 2.7 X 10(-7) mol/l. More than 80% of these contractions were found to be dependent on extracellular calcium. Hyperpolarization of cell membrane by inwardly applied electrical current caused nearly 50% reduction in serotonin-induced contractions. The same portion of contractions was inhibited by verapamil and Ca2+. Serotonin-, but not potassium-induced contractions were completely inhibited by sodium nitroprusside which is thought to be selective inhibitor of receptor-operated calcium channels. These findings could indicate that Ca2+ ions, responsible for serotonin-induced contractions enter the cell from the outer surface of the cellular membrane via receptor-operated calcium channels. Nearly half of serotonin-operated Ca2+ channels appear to be also potential-operated.

[Electrophysiological analysis of the action of kavinton on the smooth muscles]. / Elektrofiziologicheskii analiz deistviia kavintona na gladkie myshtsy.

Cavinton at a concentration of 10(-7)-10(-5) M was found to have a dose-dependent relaxing effect on bovine cerebral artery smooth muscles, without changing the resting potential and membrane resistance. Smooth muscles of the rabbit portal vein and guinea-pig taenia coli were insensitive to low cavinton concentrations. The results are consistent with the hypothesis that relaxing action of cavinton is due to the blocking of Ca2+ ions influx into the cells of cerebral artery through receptor-operated calcium channels. At higher concentrations (exceeding 10(-5) M) cavinton exerts nonspecific influence on the smooth muscles under study, inhibiting their excitability and decreasing membrane resistance resulting in the attenuation of tetanic contractions in the smooth muscles of the portal vein and taenia coli.

[Electrical properties and transmembrane ion currents of single smooth-muscle cells]. / Elektricheskie svoistva i transmembrannye ionnye toki odinochnykh gladkomyshechnykh kletok.

Current and voltage clamp investigations of freshly isolated smooth muscle cells from guinea-pig ileum and taenia coli were performed using single suction micropipette technique. Specific membrane capacity of smooth muscle cells was calculated and accounted for 1.6 microF/cm2, with specific resistance varying from 50 to 150 k omega X cm2. Transmembrane currents consisted of two inward components, inactivating and noninactivating ones, carried by Ca2+ ions, overlapping with early activated potassium outward current. Time constant of inward current activation was not only voltage-sensitive but also ion-dependent. When Ca2+ ions in Krebs solution were replaced by Ba2+, both the rate of activation and inactivation of inward current were significantly reduced. Estimation of intracellular Ca2+ concentration increase has indicated that inward calcium current transports enough Ca2+ for direct contraction activation.