Carbamate-induced rhythmic activity in the guinea-pig ileum.
The action of newly synthesised basic esters of alkoxy-substituted derivatives of phenylcarbamic acid was compared with that of procaine and trimecaine in the guinea-pig small intestine. Some of the carbamate local anaesthetics, in concentrations high enough to markedly suppress cholinergic twitches, elicited regular rhythmic activity of the guinea-pig ileum. This effect of the carbamates was dependent on the position of the alkoxysubstituent and was independent of the basic group (pyrrolidine, piperidine or perhydroazepine) present. Only the ortho-substituted derivatives were active. It was also found that the rhythmic activity evoked was of myogenic origin, produced by rhythmic undulations of the sodium-pump activity, accompanied by a potential-dependent change in Ca2+ permeability. It is suggested that the mechanism by which carbamates reveal this endogenous rhythm in the guinea-pig ileum could be a selective block of noncholinergic, nonadrenergic innervation or the TEA-like activity of carbamates.
D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002219:Carbamates / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D003106:Colon / Q000187:drug effects; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology
D000779:Anesthetics, Local; D002219:Carbamates; D010880:Piperidines; C013549:heptacaine; D010042:Ouabain