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β CELL MEMBRANE POTENTIAL AND INSULIN RELEASE; ROLE OF CALCIUM AND CALCIUM: MAGNESIUM RATIO
Author(s) -
Atwater Illani,
Frankel Barbara J.,
Rojas Eduardo,
Grodsky Gerold M.
Publication year - 1983
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1983.sp002715
Subject(s) - calcium , insulin , endocrinology , medicine , chemistry , extracellular , magnesium , islet , biophysics , biology , biochemistry , organic chemistry
Glucose‐induced insulin release from perfused rat pancreas was compared with glucose‐induced changes in membrane potential of β cells from mouse islets. Extracellular concentrations of Ca and Mg were varied as steps, simultaneously or separately, from 10% to 200% of normal in the presence of 11·1 mM glucose. A change in Ca induced a transient change in electrical activity paralleled by a transient change in insulin release. If the Ca/Mg ratio was maintained, steady‐state insulin release remained constant between 10% and 200% Ca, while electrical activity showed alterations. Analysis of burst parameters indicated that increased or decreased Ca entry was balanced by decreased or increased excitability. It is postulated that the β cell contains a compensator mechanism for the regulation of Ca influx.