[Effect of an increase in the intracellular concentration of calcium ions on the transmembrane current induced by iontophoretic injection of cAMP into Helix pomatia neurons].

The effect of intracellular Ca2+ concentration increase on transmembrane current induced by cAMP injection into a neuron (cAMP-current) was studied on Helix pomatia neurons under voltage clamp conditions. The elevation of intracellular Ca2+ concentration was produced by iontophoretic injection of Ca2+ into the cytoplasm, generation of action potentials, addition of uncouplers of oxidative phosphorylation into the external solution resulting in Ca2+ efflux from mitochondria. It was found that elevation of the intracellular Ca2+ concentration increases the amplitude of the cAMP-current and in most cases its duration as well. It is suggested that membrane structures responsible for the cAMP-current have two centers of phosphorylation: cAMP-dependent and Ca2+-calmodulin-dependent. Possible role of the studied process in integration of signals on the intraneuronal level is discussed.