Ca(2+)-induced Ca2+ release in insulin-secreting cells.
The sulphydryl reagent thimerosal (50 microM) released Ca2+ from a non-mitochondrial intracellular Ca2+ pool in a dose-dependent manner in permeabilized insulin-secreting RINm5F cells. This release was reversed after addition of the reducing agent dithiothreitol. Ca2+ was released from an Ins(1,4,5)P3-insensitive pool, since release was observed even after depletion of the Ins(1,4,5)P3-sensitive pool by a supramaximal dose of Ins(2,4,5)P3 or thapsigargin. The Ins(1,4,5)P3-sensitive pool remained essentially unaltered by thimerosal. Thimerosal-induced Ca2+ release was potentiated by caffeine. These findings suggest the existence of Ca(2+)-induced Ca2+ release also in insulin-secreting cells.
Islam
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Rolf Luft Center for Diabetes Research, Department of Endocrinology, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
Rorsman
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Berggren
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D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D002463:Cell Membrane Permeability; D004229:Dithiothreitol / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D013849:Thimerosal / Q000494:pharmacology
D007328:Insulin; D013849:Thimerosal; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D004229:Dithiothreitol