Cyclic AMP-induced depolarization measured by bis-oxonol fluorescence in bovine adrenal medullary chromaffin cells

Effects of cyclic AMP on membrane potentials were examined by measuring the changes of bis-oxonol fluorescence in bovine adrenal medullary chromaffin cells. 8-Bromo cyclic AMP (8Br-cAMP) or forskolin caused a gradual and long lasting increase of the fluorescence intensity. The effects of 8br-cAMP wa...

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Bibliographic Details
Published in:Journal of Neural Transmission 1994-01, Vol.97 (1), p.65-72
Main Authors: MINAMI, N, MORITA, K, SUEMITSU, T, MIYASAKO, T, DOHI, T
Format: Article
Language:English
Subjects:
Adrenals. Interrenals
Adrenomedullary hormones. Regulation
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Vertebrates: endocrinology
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Summary:Effects of cyclic AMP on membrane potentials were examined by measuring the changes of bis-oxonol fluorescence in bovine adrenal medullary chromaffin cells. 8-Bromo cyclic AMP (8Br-cAMP) or forskolin caused a gradual and long lasting increase of the fluorescence intensity. The effects of 8br-cAMP was blocked by cyclic AMP-dependent protein kinase inhibitor, adenosine-3',5'-cyclic monophosphothioate, Rp-diastereomer (Rp-cAMPS) and there was no further increase in the fluorescence by 8br-cAMP in the cells depolarized with 56 mM KCl or gramicidin D. Ouabain or the removal of extracellular K super(+) ([K super(+)] sub(0) free) which block Na super(+), K super(+)-ATPase also increased the fluorescence. The results may suggest that cyclic AMP causes the membrane depolarization by accumulating Na super(+) through the inhibition of Na super(+), K super(+)-ATPase in adrenal chromaffin cells.
ISSN:0300-9564
1435-1463
DOI:10.1007/BF01277963