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Insulin release has no absolute requirement for extracellular monovalent ions
Author(s) -
Hermans M.P.,
Henquin J.C.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80593-2
Subject(s) - exocytosis , extracellular , insulin , biophysics , chemistry , membrane , cobalt , biochemistry , inorganic chemistry , biology , endocrinology
Current chemiosmotic models of exocytosis ascribe an essential role to the influx of extracellular monovalent anions or cations into the secretory granules apposed to the plasma membrane. These hypotheses were tested by measuring insulin release in sucrose media devoid of monovalent ions. A small response to glucose (25% of controls) was still observed, which could be potentiated by isobutylmethylxanthine and suppressed by cobalt or low temperature. Substitution of Ba 2+ for Ca 2+ triggered a practically normal release of insulin that was inhibited by blockers of Ca 2+ channels (cobalt or D 600) and abolished by low temperature. These results show that insulin release remains possible in the absence of extracellular monovalent ions and, therefore, that the chemiosmotic models of exocytosis do not entirely apply to insulin release.