Accession Number : ADA290643
Title : Correlation of Real-Time Catecholamine Release and Cytosolic CA2+ at Single Bovine Chromaffin Cells.
Descriptive Note : Technical rept. no. 9,
Corporate Author : NORTH CAROLINA UNIV AT CHAPEL HILL DEPT OF CHEMISTRY
Personal Author(s) : Finnegan, Jennifer M. ; Wightman, R. M.
PDF Url : ADA290643
Report Date : 13 JAN 1995
Pagination or Media Count : 32
Abstract : Previous investigations of the role of Ca2+ in stimulus-secretion coupling have been undertaken in populations of adrenal chromaffin cells. In the present study, the simultaneous detection of intracellular Ca2+, with the fluorescent probe fura-2, and catecholamine release, using a carbon-fiber microelectrode, are examined at single chromaffin cells in culture. Results from classic depolarizing stimuli, high potassium (30-140 mM) and 1,1-dimethyl-4-phenylpiperazinium (DMPP) (3-50 uM), show a dependence of peak cytosolic Ca2+ concentration and catecholamine release on secretagogue concentration. Catecholamine release induced by transient high K+ stimulation increases logarithmically with K+ concentration. Continuous exposure to veratridine (50 uM) induces oscillations in intracellular Ca2+, and at higher concentrations (100 uM) concomitant fluctuation of cytosolic Ca2+ and catecholamine secretion. Mobilization of both caffeine- and IP3-sensitive intracellular Ca2+ stores is found to elicit secretion with or without extracellular Ca2+. Caffeine-sensitive intracellular Ca2+ stores can be depleted, refilled, and cause exocytosis in medium without Ca2+. Single-cell measurement of exocytosis and the increase in cytosolic Ca2+ induced by bradykinin-activated intracellular stores reveal cell-to-cell variability in exocytotic responses which is masked in populations of cells. Taken together, these results show that exocytosis of catecholamines can be induced by an increase in cytosolic Ca2+ either as a result of trans membrane entry or by release of internal stores.
Descriptors : *CALCIUM, *MICROELECTRONICS, *CATECHOLAMINES, DETECTION, REAL TIME, MOBILIZATION, CHEMICAL PROPERTIES, CELLS, POPULATION, CONCENTRATION(COMPOSITION), RELEASE, SYNCHRONISM, BOVINES, POTASSIUM, OSCILLATION, CAFFEINE, SECRETION, CHROMIUM COMPOUNDS, ADRENAL GLANDS.
Subject Categories : Inorganic Chemistry
Atomic and Molecular Physics and Spectroscopy
Distribution Statement : APPROVED FOR PUBLIC RELEASE