[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.

[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.