Enhancers of cytosolic cAMP augment depolarization-induced exocytosis from pancreatic B-cells: evidence for effects distal to Ca2+ entry

Pflugers Arch. 1993 Jul;424(2):195-7. doi: 10.1007/BF00374612.

Abstract

We have investigated the effects of cAMP-enhancing agents on depolarization-induced membrane capacitance increases (delta Cm) in single rat pancreatic B-cells. Concentrations of IBMX, 8-CPT cAMP and forskolin, which enhance cAMP and insulin release, all enhance depolarization-induced delta Cm's seen in response to single voltage-clamp pulses and reduce the depression of delta Cm responses often seen with trains of pulses. These effects often occur in the absence of changes in peak Ca2+ current or the total Ca2+ charge entry during the depolarizing pulse. These data suggest that cAMP-modulating maneuvers may directly affect the mechanism of insulin granule mobilization into a readily releasible store or fusion at a discharge site.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Animals
  • Calcium Channels / drug effects
  • Calcium Channels / metabolism*
  • Cells, Cultured
  • Colforsin / pharmacology
  • Cyclic AMP / analogs & derivatives
  • Cyclic AMP / metabolism*
  • Cyclic AMP / pharmacology
  • Cytosol / drug effects
  • Cytosol / metabolism*
  • Electrophysiology
  • Exocytosis / drug effects*
  • Insulin / metabolism
  • Insulin Secretion
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism*
  • Rats
  • Thionucleotides / pharmacology

Substances

  • Calcium Channels
  • Insulin
  • Thionucleotides
  • Colforsin
  • 8-((4-chlorophenyl)thio)cyclic-3',5'-AMP
  • Cyclic AMP
  • 1-Methyl-3-isobutylxanthine