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Type: Artigo de periódico
Title: Tetracaine stimulates extracellular Ca2+-independent insulin release
Author: Bordin, S
Carneiro, EM
Bosqueiro, JR
Boschero, AC
Abstract: The effect of the local anesthetic, tetracaine, on Ca-45 efflux, cytoplasmic Ca2+ concentration [Ca2+](i) and insulin secretion in pancreatic B-cells was studied. At a physiological level of [Ca2+](o), tetracaine (0.1-5 mM) dose-dependently inhibited insulin secretion induced by 22 mM glucose. Paradoxically, at the same glucose concentration but in the absence of external Ca2+, tetracaine dose-dependently increased insulin secretion. At a low glucose level (2.8 mM) tetracaine failed to affect secretion, either in the presence or absence of external Ca2+. At high (12 mM) or low (2.8 mM) glucose, [Ca2+](i) was increased by tetracaine in a dose-dependent manner. Tetracaine (2 mM) also increased the Ca-45 efflux from isolated islets. This effect was of the same magnitude at both low and high glucose concentrations, and was independent of the presence of extracellular Ca2+. Finally, tetracaine increased Ca-45 efflux from islets perifused in the presence of thapsigargin. In conclusion, our data indicate that tetracaine releases Ca2+ from a thapsigargin-insensitive store in pancreatic B-cells. Under suitable experimental conditions, insulin release can be elicited by a [Ca2+](o)-independent pathway. The existence of a ryanodine-like Ca2+ channel in pancreatic B-cells is proposed.
Subject: pancreatic B-cell
insulin secretion
Country: Holanda
Editor: Elsevier Science Bv
Citation: European Journal Of Pharmacology. Elsevier Science Bv, v. 327, n. 41700, n. 257, n. 262, 1997.
Rights: fechado
Identifier DOI: 10.1016/S0014-2999(97)89669-0
Date Issue: 1997
Appears in Collections:Unicamp - Artigos e Outros Documentos

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