Protein kinase C enhances exocytosis from chromaffin cells by increasing the size of the readily releasable pool of secretory granules

Neuron. 1996 Jun;16(6):1209-20. doi: 10.1016/s0896-6273(00)80147-6.


We have used membrane capacitance measurements to assay Ca2+-triggered exocytosis in single bovine adrenal chromatin cells. Brief application of phorbol ester (PMA) enhances depolarization-evoked exocytosis severalfold while actually decreasing the Ca2+ current. Ca2+ metabolism is unchanged. Three different protocols were used to show that PMA increases the size of the readily releasable pool of secretory granules. PMA treatment leads to a large increase in amplitude, but little change in the time course of the exocytic burst that results from rapid elevation of [Ca2+]i upon photolysis of DMI-Nitrophen. Thus, PKC appears to affect a late step in secretion but not the Ca2+ sensitivity of the final step.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / physiology
  • Cattle
  • Chromaffin System / physiology*
  • Dose-Response Relationship, Drug
  • Exocytosis / physiology*
  • Kinetics
  • Membrane Potentials / physiology*
  • Protein Kinase C / physiology*


  • Protein Kinase C
  • Calcium