[Identification of cholinoreceptors on the soma of RPa3 and LPa3 neurons in Helix lucorum].

Abstract

Selective cholinomimetics and cholinolytics were employed to identify cholinoreceptors on the somatic membrane in Helix lucorum RPa3 and LPa3 neurons using recording of transmembrane ionic currents. Agonists of nicotinic and muscarinic cholinoreceptors evoked reversible activation and following nonreversible inhibition of receptors (except carbamylcholine). Selective cholinomimetics were connected with the same membrane sites that were activated by acetylcholine. Nicotinic and muscarinic cholinolytics decreased the amplitude of inward current induced by acetylcholine (scopolamine and platyphylline had no effect). It is concluded that somatic membrane of RPa3 and LPa3 Helix neurons contains nicotinic and muscarinic cholinoreceptors. These receptors have several pharmacological peculiarities as compared with those of the vertebrates. Muscarinic cholinoreceptors of RPa3 and LPa3 neurons must be included into a special subtype that differs from well-known M1 and M2 subtypes.