Ca2+ signalling in rat chromaffin cells: interplay between Ca2+ release from intracellular stores and membrane potential

Cell Calcium. 1996 Feb;19(2):113-23. doi: 10.1016/s0143-4160(96)90080-9.

Abstract

Cytosolic Ca2+ oscillations are physiologically important in a range of excitable and non-excitable cells. The combined techniques of whole-cell patch clamp and photometric measurement of cytosolic Ca2+ has enabled us to identify the components of Ca2+ spiking in rat chromaffin cells. We show that Ca2+ oscillations continue at a fixed membrane potential and that infusion of the InsP3 receptor antagonist, heparin, substantially blocked the cytosolic Ca2+ spikes. However, even in the presence of heparin we observed spikes of membrane potential depolarization due to the repetitive activation of a transient inward cation current. We conclude that Ca2+ oscillations are dependent on Ca2+ release from heparin sensitive Ca2+ stores and possibly on Ca2+ entry associated with the repetitive activation of a transient cation current. The depolarizing action of the cation current would, in turn, recruit voltage-sensitive Ca2+ channels and further Ca2+ entry would augment the cytosolic Ca2+ spikes. Our results demonstrate that Ca2+ oscillations in rat chromaffin cells are due to a complex interplay of Ca2+ entry and Ca2+ release.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Medulla / cytology
  • Adrenal Medulla / metabolism
  • Animals
  • Bradykinin / pharmacology
  • Calcium / metabolism*
  • Cations
  • Cells, Cultured
  • Chromaffin System / cytology
  • Chromaffin System / drug effects
  • Chromaffin System / metabolism*
  • Dose-Response Relationship, Drug
  • Female
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction

Substances

  • Cations
  • Inositol 1,4,5-Trisphosphate
  • Bradykinin
  • Calcium