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Insulin release independent of a rise in cytosolic free Ca 2+ by forskolin and phorbol ester
Author(s) -
Tamagawa Tatsuo,
Niki Hatsumi,
Niki Atsushi
Publication year - 1985
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(85)80825-5
Subject(s) - phorbol ester , forskolin , cytosol , insulin , chemistry , phorbol , biochemistry , microbiology and biotechnology , endocrinology , medicine , biophysics , protein kinase c , biology , enzyme , receptor
The role of cytosolic free Ca 2+ in insulin release was evaluated using isolated rat pancreatic islets permeabilized with digitonin and incubated in Ca‐EGTA buffers to fix free Ca 2+ concentration at arbitrary levels. Ca 2+ induced insulin release in a concentration‐dependent manner with the threshold being between 0.1 and 1 μM. The hormone release was increased by forskolin and 12‐ O ‐tetradecanoyl phorbol‐13‐acetate (TPA), a potent activator of adenylate cyclase and that of protein kinase C, respectively. The findings suggest that activation of both protein kinase A and protein kinase C modulate insulin release without a concomitant increase in cytosolic free Ca 2+ .