Stimulation of insulin release by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate in the clonal cell line RINm5F despite a lowering of the free cytoplasmic Ca2+ concentration

Per Arkhammar, Thomas Nilsson, Per Olof Berggren

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The effects of 12-O-tetradecanoylphorbol 13-acetate (TPA) on the handling of Ca2+ and insulin release were investigated in the clonal insulin-producing cell line RINm5F. The presence of the phorbol ester lowered the free cytoplasmic Ca2+ and suppressed the increase obtained by depolarization with high concentrations of K+. Despite the lowering in cytoplasmic Ca2+ by TPA, there was a concomitant stimulation of insulin release indicating that one feature of protein kinase C activation is to make the secretory system more sensitive to Ca2+. Furthermore, there was no interaction of TPA with the mechanisms responsible for inositol 1,4,5-tris(phosphate) induced Ca2+ release or Ca2+ uptake in permeabilized cells. Although TPA slightly depolarized the RINm5F cells there was no interference with K+-induced depolarization. It is suggested that an additional effect of protein kinase C activation in these cells, is to stimulate the extrusion of Ca2+ over the plasma membrane.

Original languageEnglish (US)
Pages (from-to)236-241
Number of pages6
JournalBBA - Molecular Cell Research
Volume887
Issue number2
DOIs
StatePublished - Jul 11 1986

Keywords

  • (RINm5F cell)
  • cytoplasmic Ca
  • Insulin release
  • Phorbol ester

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology

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