Changes in intracellular potentials of snail neurons induced by ß-phenylglutamic acid hydrochloride.

ß-Phenylglutamic acid hydrochloride (RGPU-135, neuroglutamine, or glutarone) in concentrations of 1, 10, 100, and 1000 µM reversibly and dose-dependently modulated the intracellular action potentials in Plantorbarius corneus snail neurons and hyperpolarized the membrane by 9.1±2.5% with maximum shift of resting potential at 100 µM. Hyperpolarization was accompanied by up-regulation of synaptic activity and changes in the pattern of impulse activity manifested by a decrease in the discharge rate, shortening of the interburst time, increase in the mean number of spikes in the bursts, and shortening of the interspike time within the bursts. Both hyperpolarization and impulse activity rearrangement persisted for 10-20 min after washing of RGPU-135.

[Influence of RGPU-207 compound and amiodarone on ion currents in shellfish neurons].

RGPU-207 compound and amiodarone in concentrations of 1, 10, 100 and 1000 microM produce dose-dependent and reversible effects on trans-membrane sodium, calcium, and potassium ion currents of neurons in pond snail and orb snail shellfish. In concentration of 1 microM, both compounds increased the amplitude of potassium ion currents, while not affecting the amplitude of sodium and calcium ion currents. In concentrations of 100 and 1000 microM, dose-dependent suppression of all currents (with predominant potassium ion current suppression) was observed. Under the action of RGPU-207 compound, the kinetics of activation and inactivation of sodium and calcium ion currents was not changed, but the kinetics of activation of the potassium slow current was slowing down. Amiodarone decelerated the inactivation of calcium ion current and accelerated the inactivation of potassium slow current. RGPU-207 compound, in comparison to amiodarone, produces a similar membranotropic effect on the shellfish neurons.

Effect of metabotropic receptor agonists on ionic current of snail neurons.

The dose-dependent and reversible changes of sodium (I(Na)), calcium (I(ca)), slow potassium (I(Ks)), and fast potassium (I(Kf)) currents were recorded in isolated snail neurons under the action of κ-opioid agonist butorphanol and chemical agent RU-1203 applied in a concentration range of 1-1000 µM.

[Afobazole effect on the electrical activity of neurons].

Changes in the membrane rest potential (RP), action potential (AP) and impulse activity (IA) in neurons of isolated central nervous system of Lymnaea stagnalis and Planorbarius corneus under the action of anxiolytic afobazole (2-mercaptobenzimidazole derivative) in 1, 10, 100 and 1000 microM concentrations have been studied using a microelectrode technique. It is established that afobazole produces a two-phase, dose-dependent and reversible effect on the electrical activity of neurons. Hyperpolarization by 5-8 mV in the first phase (1-100 microM) and depolarization by 8-10 mV in the second phase (1000 microM) have been observed. The corresponding changes in AP and IA parameters were due to the RP level changes related to their potential dependence and resulted from the direct activation-suppression action of afobazole on the neuron ionic currents.

Elucidation of the mechanisms of membranotropic effects of RU-1203 on ionic channels of Lymnaea stagnalis neurons.

RU-1203-induced norBNI-irreversible inhibition of sodium (INa), calcium (ICa), and slow and fast potassium currents (IKs and IKf) was demonstrated in isolated neurons of Lymnaea stagnalis.

[The new glutamic acid derivative RGPU-135 (glutaron, neuroglutamin) modulates ion currents in mollusk neurons].

The new glutamic acid derivative RGPU-135 (3-phenylglutamic acid hydrochloride, glutaron, neuroglutamin) produces dose-dependent and reversible modulation of transmembrane sodium, potassium and, to a greater extent, calcium ion currents in neurons of Lymnaea stagnalis and Planorbarius corneus mollusks at concentrations of 1, 10, 100, and 1000 microM. At concentrations within 1 - 10 microM micromole, Ca and K currents are activated rather insignificantly; at 100 pmole, the amplitude of calcium currents is increased by 5 - 10%; and at 1000 microM, the Na and K ion currents are suppressed by 5 - 12%. RGPU-135 does not influence the membrane surface charge potential and the gating of ion channels. The effects of RGPU-135 were quickly reversible, which indicated the relatively weak drug binding to the membrane structures and ion channels.

[Effects of digoxin and corglycon on ion currents in neuronal membrane of snail (Lymnaea stagnalis)].

The results of endocellular dialysis membrane potential monitoring show that cardiac glycosides digoxin and corglycon in concentration from 10(-12) to 10(-6) M influence the sodium, calcium and potassium ion currents in isolated snail (Lymnaea stagnalis) neurons in reversible and slightly dose-dependent manner. In low concentration (10(-12) - 10(-8) M) both substances increased all ionic currents by up to 5%, while in higher concentrations both drugs led to the suppression of ion currents. The most pronounced decrease (up to 26% relative to control) was observed for sodium ion current under the action of digoxin in a concentration of 10(-6) M. The process of slow potassium currents inactivation was accelerated by corglycon in a concentration of 10(-6) M. Digoxin caused a shift in the current - voltage curve maximum by 5 - 10 mV to the right on the potential axis. Generally, digoxin in comparison to corglycon produced less activating and more suppressing effect on the membrane ion currents studied.

[Strophanthin induced changes in the ion currents of Lymnaea stagnalis and Planorbis corneus neurons].

Experiments on isolated neurons of Lymnaea stagnalis and Planorbis corneus using the intracellular dialysis and fixed membrane potential techniques showed that strophanthin G in a concentration range from 10(-11) to 10(-6) M produce dolse-dependent reversible suppression of the ion currents in potassium, calcium, and sodium channels. At the maximum concentration (10(-6) M), the maximum suppression (up to 55% of that in the control) was observed for the calcium ion current. At the minimum concentration (10(-12) M), the drug did not influence the sodium ion current, but slightly (approximately by 5%) increased the calcium and potassium ion currents. In addition, strophanthin accelerated the inactivation of slow potassium ion currents.

[The influence of ecdysteroid fraction from Serratula coronata on transmembrane ionic currents of snail neurons].

Changes of the transmembrane potassium, calcium, and sodium ion currents in isolated neurons of Lymnaea stagnalis snail under the action of ecdysteroid fraction (serpisten) from Serratula coronata L. applied from outside in 0.01 -1000 microg/ml concentrations have been studied using the voltage-clamp technique. It is established for the first time that serpisten non-selectively activates the potassium and calcium ion currents (the currents amplitude increases by 2 - 15%) and reduces nonspecific membrane leakage currents in the entire range of concentrations. The sodium ion current also increased by 4 - 7% under the action of Serpisten in low concentrations (0.01 -10 microg/ml) in comparison with control, but this current decreased by 5 -10% at serpisten concentrations of 100 and 1000 microg/ml. The effects were reversible. The kinetics of currents was not changed under the action of serpisten.

[Effect of afobazole on transmembrane ion currents in mollusk neurons].

The effect of anxiolytic afobazole (2-[2-morpholino)ethylthio]-5-ethoxybenzimidazole dihydrochloride) at concentrations of 1, 10, 100 and 1000 microM on transmembrane calcium, sodium, and potassium (slow and rapid) ion currents in isolated neurons of Lymnaea stagnalis mollusks have been investigated. Afobazole was found to produce a dose-dependent reversible action: the drug increased all ion currents at concentrations below 100 microM and inhibited all ion currents at concentrations from 100 to 1000 microM. Afobazole at high concentrations accelerated the inactivation of slow potassium ion current and reversibly inhibited the fast potassium ion current.

[A comparative study of the effect of brazidole, amiodarone, sotalol, and hydroxyzine on potassium ionic channels of mollusks neurons].

Intracellular dialysis and fixed membrane potential techniques were used to study the extracellular influence of antiarrhythmic drugs--brazidole (a new derivative of 2-mercaptobenzimidazole), amiodarone, sotalol, and hydroxyzine (a tranquilizer) in concentrations 1, 10, 100 and 1000 microM--on the slow potassium ionic transmembrane current in isolated neurons of Lymnnaea stagnalis mollusks. All drugs produced a doze-dependent and reversible suppression of the potassium ion current and accelerated the inactivation kinetics. With respect to the degree of current suppression at 100 microM concentration, the preparations under study can be arranged in the following order: brazidole = hydroxyzine > amiodarone > sotalol. The drugs influence the membrane stability by changing nonspecific leak currents. The antiarrhythmic action of bradizole can be related to its high membranotropic activity.

Effects of helium-neon laser irradiation and local anesthetics on potassium channels in pond snail neurons.

Intracellular dialysis and membrane voltage clamping were used to show that He-Ne laser irradiation of a pond snail neuron at a dose of 0.7 x 10(-4) J (power density 1.5 x 10(2) W/m2) increases the amplitude of the potential-dependent slow potassium current, while a dose of 0.7 x 10(-3) J decreases this current. Bupivacaine suppresses the potassium current. Combined application of laser irradiation at a dose of 0.7 x 10(-3) J increased the blocking effect of 10 microM bupivacaine on the slow potassium current, while an irradiation dose of 0.7 x 10(-4) J weakened the effect of bupivacaine.

[Influence of He-Ne laser irradiation and local anesthetics on potassium channels in the snail neurons]. / Deistvie gelii-neonovogo lazernogo izlucheniia na kalievye kanaly neironov prudovika.

Using clamp method it had been shown that He-Ne laser irradiation of the snail neurons increases the amplitude of voltage-gated slow potassium currents in dose of 0.7 x 10(-4) (fluence 1.5 x 10(2) Wt/m2) and decreases it in dose 0.7 x 10(-3). Bupivacaine and lidocaine suppressed potassium currents. Laser irradiation in dose 0.7 x 10(-3) enhanced the inhibitory effect of bupivacaine (10 mcM) and in dose 0.7 x 10(-4) it decreased the inhibitory effect of bupivacaine. The results of the study suggest mechanisms of the He-Ne laser irradiation effect in combination with pharmacological substances on ion channels of electrically excitable cells.

Activating effect of Tanacetum vulgare L. pectin polysaccharide on ionic channels of neuronal membrane.

The membranotropic effects of TVF tanacetan pectin polysaccharide derived from Tanacetum vulgare L. was studied by the voltage-clamp method on isolated neurons of Lymnaea stagnalis mollusk. TVF in concentrations of 0.1-10.0 microg/ml nonselectively activated the outward potassium and total inward (sodium and calcium) ionic currents (slightly dose-dependently and reversibly increased their amplitude by 5-10%) and decreased nonspecific leakage current.

[Effect of the He-Ne laser irradiation on resistance of the isolated heart to the ischemic and reperfusion injury]. / Vliianie izlucheniia He-Ne lazera na ustoichivost' izolirovannogo serdtsa k ishemicheskomu i reperfuzionnomu povrezhdeniiu.

The aim of this work was to investigate the myocardial protection against ischemia/reperfusion using low level laser irradiation (LLLI). It has been shown that pulse pressure was higher in the period of post-ischemic reperfusion as compared with the control group. It provided a better restoration of myocardial contractility as well as increasing of coronary flow in the reperfusion period. The amount of ventricular rhythm disorder episodes decreased. These effects of laser application were registered in conditions of coronary flow reduction less than 50%. One of the suggested mechanisms of laser effect is an ATP-sensitive channel activation.

[Membrane mechanisms of effects of antihypoxic agents bemethyl and almide on neurons of Mollusca]. / Membrannye mekhanizmy deistviia antigipoksantov bemitila i almida na neirony molliuskov.

Membranotropic effects of the antihypoxants bemithyl and almide, structural analogs of thiobenzimidazole, have been studied on the isolated neuronal preparations of Lymaea stagnalis branchycephalic mollusk. Both drugs in a concentration range of 100-1000 microM produced a reversible, dose-dependent nonselective single-phase blocking action upon the ion channels and completely blocked the channels at a concentration of 10 mM. Therefore, bemithyl and almide are active membranotropic compounds capable (in sufficiently high concentrations) of changing the conductivity of slow sodium, calcium, and potassium ion channels in excitable cells. The protective antihypoxant drug reactions on a systemic level of the organism are probably related to the fact that both drugs in small concentrations are capable of hyperpolarizing the cell membrane, activating the ion channel function, and stabilizing the action potential under hypoxia conditions; in greater concentrations, bemithyl and almide are capable of blocking ion currents, thus reducing the excitability of cells and protecting them from overstress.

[Effects of opioid analgesics on potential-gated ion channels in the pond snail neurons]. / Vliianie opioidnykh anal'getikov na potentsialupravliaemye ionnye kanaly neironov prudovika.

The effects of opioid analgesics morphine, promedol, tramadol, and butorphanol on the transmembrane calcium, sodium, and potassium (fast and slow) ion currents in pond snail (Lymnaea stagnalis) neurons were studied by intracellular dialysis and membrane potential (voltage-clamp) measurements. It was established that all these drugs produce a dose-dependent reversible inhibition of the ion currents (sodium calcium potassium) and reduce nonspecific leak currents, thus producing a stabilizing action upon the sample membrane. The current-inhibiting effect of morphine was not eliminated by naloxone (500 microM); moreover, the latter drug significantly inhibited the ion currents as well.

[The effect of clofelin, guanfacine and compound SHA-9 on the transmembrane ion potentials of snail neurons]. / Vliianie klogfelina, guanfatsina i soedineniia SHA-9 na transmembrannye ionnye toki neironov prudovika.

The effect of central adrenopositive drugs--clopheline, guanfacine, and 2,4,6-trifluorine derivative of clopheline (SHA-9)--on Na, Ca, fast and slow K transmembrane ion currents in Lymnaea stagnalis neurons was studied using the intercell dialysis and voltage-clamp upon bath application of the drugs in doses 1-1000 microM. A dose-dependent reversible suppression of the ion (Na > Ca > K) currents and nonspecific leakage currents is observed. The membrane stabilizing effect of the drugs comes out in descending order SHA-9 > clopheline > guanfacine.

[The calcium channels of cell membranes]. / Kal'tsievye kanaly kletochnykh membran.

On the basis of the literature findings, the modern ideas about the structure and function of calcium canals of plasmatic and intracellular membranes of the living cells are generalized and systematized. The major electrophysiologic and chemical properties of the main groups and types of potential-controlled and receptor-controlled calcium canals are reviewed. The article gives the classification and nomenclature of the calcium canals as well as the characteristics of different types of calcium antagonists and the cases of their clinical application.