Exocytosis of catecholamine (CA)-containing and CA-free granules in chromaffin cells

J Biol Chem. 2001 Oct 26;276(43):39974-9. doi: 10.1074/jbc.M106498200. Epub 2001 Aug 27.

Abstract

Recent evidence suggests that endocytosis in neuroendocrine cells and neurons can be tightly coupled to exocytosis, allowing rapid retrieval from the plasma membrane of fused vesicles for future use. This can be a much faster mechanism for membrane recycling than classical clathrin-mediated endocytosis. During a fast exo-endocytotic cycle, the vesicle membrane does not fully collapse into the plasma membrane; nevertheless, it releases the vesicular contents through the fusion pore. Once the vesicle is depleted of transmitter, its membrane is recovered without renouncing its identity. In this report, we show that chromaffin cells contain catecholamine-free granules that retain their ability to fuse with the plasma membrane. These catecholamine-free granules represent 7% of the total population of fused vesicles, but they contributed to 47% of the fusion events when the cells were treated with reserpine for several hours. We propose that rat chromaffin granules that transiently fuse with the plasma membrane preserve their exocytotic machinery, allowing another round of exocytosis.

Publication types

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

MeSH terms

  • Animals
  • Catecholamines / metabolism*
  • Cells, Cultured
  • Chromaffin Cells / cytology
  • Chromaffin Cells / physiology*
  • Chromaffin Granules / physiology*
  • Electric Conductivity
  • Endocytosis / physiology
  • Exocytosis / physiology*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Catecholamines