title: Effects of procaine on a central neuron of the snail, Achatina fulica Ferussac.
abstract: Effects of procaine on a central neuron (RP1) of the giant African snail (Achatina fulica Ferussac) were studied pharmacologically. The RP1 neuron showed spontaneous firing of action potential. Extra-cellular application of procaine (10 mM) reversibly elicited bursts of potential. The bursts of potential elicited by procaine were not blocked after administration of (1) prazosin, propranolol, atropine, d-tubocurarine, (2) calcium-free solution, (3) ryanodine (4) pretreatment with KT-5720 or chelerythrine. The bursts of potential elicited by procaine were blocked by adding U73122 (10 microM) and the bursts of potential were decreased if physiological sodium ion was replaced with lithium ion or incubated with either neomycin (3.5 mM) or high magnesium solution (30 mM). Preatment with U73122 (10 microM) blocked the initiation of bursts of potential. Ruthenium red (100 microM) or caffeine (10 mM) facilitated the procaine-elicited bursts of potential. It is concluded that procaine reversibly elicits bursts of potential in the central snail neuron. This effect was not directly related to (1) the extra-cellular calcium ion fluxes, (2) the ryanodine sensitive calcium channels in the neuron, or (3) the PKC or PKA related messenger systems. The procaine-elicited bursts of potential were associated with the phospholipase activity and the calcium mobilization in the neuron.
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University, No.1, Sec.1, Jen-Ai Road, Taipei, Taiwan.
authors.forename: Chia-Hsien
authors.initials: CH
authors.lastname: Lin
authors.forename: Ming-Cheng
authors.initials: MC
authors.lastname: Tsai
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D018674:Adrenergic Antagonists / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D018680:Cholinergic Antagonists / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006152:Cyclic GMP / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010740:Phospholipases / Q000378:metabolism; D011343:Procaine / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D012430:Ruthenium Red / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D012908:Snails / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D018674:Adrenergic Antagonists; D000779:Anesthetics, Local; D015220:Calcium Channels; D018680:Cholinergic Antagonists; D004791:Enzyme Inhibitors; D012430:Ruthenium Red; D012433:Ryanodine; D002110:Caffeine; D011343:Procaine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010740:Phospholipases; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D006152:Cyclic GMP; D002118:Calcium