| Abstract: | Cholinoreceptors were identified at the somatic membrane of theHelix lucorum RPa4 neuron using intracellular recording techniques. Application of specific agonists of nicotinic (nicotine, cytisine) and muscarinic (muscarine, arecoline) cholinoreceptors to the soma produced neuronal depolarization. The depolarization produced by applying acetylcholine to the cell was of short duration and was often replaced by hyperpolarization. Both selective desensitization of receptors by nicotine and muscarine as well as receptor occupancy by cytisine and arecoline reduced acetylchloline-induced response. The nicotinic cholinoblocker d-tubocurarine substantially inhibited responses to nicotinic cholinomimetics, while atropine, a muscarinic cholinoblocker, depressed response to muscarinic cholinomimetics. Acetylcholine-induced response was inhibited by both cholinoblockers more or less equally. The presence at the RPa4 neuronal somatic membrane is postulated of standard nicotinic and muscarinic cholinoreceptors similar to those found in vertebrates.M. V. Lomonsov State University, Moscow. Translated from Neirofiziologiya, Vol. 20, No. 2, pp. 203–212, March–April, 1988. |
