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Vesicular Ca(2+) -induced secretion promoted by intracellular pH-gradient disruption
Christy L Haynes1, Leah A Buhler, R Mark Wightman
1University of North Carolina, Chapel Hill, Department of Chemistry, Venable Hall, Chapel Hill, NC 27599, USA.
Biophysical Chemistry
|May 9, 2006
Summary
The protonophore CCCP disrupts intracellular calcium regulation and exocytosis in chromaffin cells by altering vesicular storage. This leads to calcium and catecholamine leakage, potentially initiating self-sustained, calcium-induced exocytosis.
Area of Science:
- Cell Biology
- Neuroscience
- Biochemistry
Background:
- Chromaffin cells are crucial for studying exocytosis and cellular regulation.
- Intracellular calcium (Ca2+) plays a vital role in regulating cellular processes, including exocytosis.
- Protonophores, like CCCP, are known to affect mitochondrial function.
Purpose of the Study:
- To investigate the effects of the protonophore CCCP on intracellular Ca2+ regulation.
- To examine the impact of CCCP on exocytosis in chromaffin cells.
- To elucidate the mechanisms by which CCCP influences vesicular Ca2+ and catecholamine storage.
Main Methods:
- Simultaneous fura-2 imaging to monitor intracellular Ca2+ levels.
- Amperometry to detect catecholamine release during exocytosis.
- Utilizing chromaffin cells as a model system.
Main Results:
- CCCP perturbs mitochondrial function and alters vesicular storage of Ca2+ and catecholamines.
- Disruption of the secretory vesicle membrane pH gradient by CCCP causes Ca2+ and catecholamine leakage into the cytosol.
- Ca2+ leakage from secretory vesicles, distinct from mitochondrial disruption, can initiate exocytotic release.
Conclusions:
- CCCP-induced disruption of vesicular pH gradients leads to Ca2+ and catecholamine release.
- This release mechanism can trigger self-sustained, Ca2+-induced exocytosis.
- Extended exposure to protonophores promotes catalytic and self-sustained vesicular Ca2+-induced exocytosis.