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.

340Local anaesthetics, anti-arrythmic, analgesic, and psychotropic agents exert diverse membranotropic effects on a nerve cell. They increase (activate) or decrease (inhibit) ionic currents through voltage-gated sodium, calcium, and potassium channels; change the membrane surface charge in the vicinity of the ion channels; inactivate the channels or counteract their inactivation. Interactions of the pharmacological agents with channel gating structures result in alteration of the activation or inactivation kinetics. Membranotropic effects cause changes in membrane resting potential, synaptic potentials, and intercellular communications. Understanding the functioning mechanisms of neurons and possible ways of regulating their state pharmacologically makes the base of the concept of the cytopharmacological management of the cell functional state.

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