ACCUMULATION OF ADENOSINE 3',5'-MONOPHOSPHATE IN BRAIN SLICES: INTERACTION OF LOCAL ANAESTHETICS AND DEPOLARIZING AGENTS |
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| Authors: | H Shimizu M Takenoshita M Huang J W Daly |
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| Institution: | Kumamoto University Medical School, First Department of Pharmacology, Kumamoto City, Japan (H.S. and M.T.) and Laboratory of Chemistry, National Institute of Arthritis, Metabolism, and Digestive Diseases, National Institutes of Health, Bethesda, MD 20014, U.S.A. (M.H. and J.W.D.) |
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| Abstract: | Abstract— Membrane depolarizing agents such as veratridine, ouabain and high concentrations of potassium ions elicit a remarkable accumulation of cyclic AMP in brain slices incubated in vitro , and this accumulation, but not that elicited by biogenic amines, is prevented by a membrane stabilizer, cocaine. The effect of various local anaesthetics (compounds which are known to stabilize the membrane of peripheral sensory nerves) on the accumulation of cyclic AMP elicited by depolarizing agents in incubated slices of guinea pig brain has now been examined. At optimal concentrations the anaesthetics inhibited by more than 95 per cent the accumulation of cyclic AMP elicited with veratridine, ouabain, and high concentrations of potassium ions. The order of the inhibitory potency vs. veratridine was: dibucaine (ED50= 9.5 ± 10?6 M) > tetracaine > cocaine (ED50= 1·3 ± 10?4 M) > lidocaine > procaine (ED50= 1.7 ± 10?3M). This order is consistent with the order of their local anaesthetic potency, but is not consonant with the order of the relative toxicity of these agents when used as spinal anaesthetics. |
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