Vesicular Ca(2+) -induced secretion promoted by intracellular pH-gradient disruption

The actions of the protonophore CCCP on intracellular Ca2+ regulation and exocytosis in chromaffin cells have been examined. Simultaneous fura-2 imaging and amperometry reveal that exposure to CCCP not only perturbs mitochondrial function but that it also alters vesicular storage of Ca2+ and catecho...

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Published inBiophysical chemistry Vol. 123; no. 1; pp. 20 - 24
Main Authors Haynes, Christy L, Buhler, Leah A, Wightman, R Mark
Format Journal Article
LanguageEnglish
Published Netherlands 20.08.2006
Subjects
Adrenal Medulla - cytology
Adrenal Medulla - secretion
Animals
Calcium - metabolism
Calcium - physiology
Carbonyl Cyanide m-Chlorophenyl Hydrazone - pharmacology
Catecholamines - metabolism
Cattle
Chromaffin Cells - secretion
Cytosol - drug effects
Cytosol - metabolism
Exocytosis - drug effects
Hydrogen-Ion Concentration
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Summary:The actions of the protonophore CCCP on intracellular Ca2+ regulation and exocytosis in chromaffin cells have been examined. Simultaneous fura-2 imaging and amperometry reveal that exposure to CCCP not only perturbs mitochondrial function but that it also alters vesicular storage of Ca2+ and catecholamines. By disrupting the pH gradient of the secretory vesicle membrane, the protonophore allows both Ca(2+) and catecholamine to leak into the cytosol. Unlike the high cytosolic Ca2+ concentrations resulting from mitochondrial membrane disruption, Ca2+ leakage from secretory vesicles may initiate exocytotic release. In conjunction with previous studies, this work reveals that catalytic and self-sustained vesicular Ca(2+) -induced exocytosis occurs with extended exposure to weak acid or base protonophores.
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ISSN:0301-4622
DOI:10.1016/j.bpc.2006.04.005