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Stimulation‐Evoked Ca 2+ Fluxes in Cultured Bovine Adrenal Chromaffin Cells Are Enhanced by Forskolin
Author(s) -
Morita Katsuya,
Dohi Toshihiro,
Kitayama Shigeo,
Kyama Yutaka,
Tsujimoto Akira
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb13155.x
Subject(s) - forskolin , endocrinology , medicine , stimulation , calcium , chemistry , acetylcholine , efflux , chromaffin cell , intracellular , catecholamine , biology , biochemistry , adrenal medulla
Forskolin, 1 μ M , increased acetylcholine (ACh)‐stimulated 45 Ca uptake by chromaffin cells. The stimulatory effects of forskolin decreased with increasing concentration of ACh. The attenuation of the effect of forskolin on 45 Ca uptake as a function of ACh concentration correlated well with changes in the forskolin effect on ACh‐evoked cate‐cholamine (CA) release. Forskolin increased excess KCl‐and veratrine‐evoked CA release and 45 Ca uptake. Forskolin by itself stimulated 45 Ca efflux and enhanced ACh‐, excess KCl‐, and veratrine‐stimulated 45 Ca efflux. High doses of forskolin inhibited both ACh‐evoked 45 Ca uptake and CA release. The inhibitory action of forskolin was specific to receptor‐mediated response because excess KCl‐and vera trine‐stimulated 45 Ca uptake and CA release were not inhibited. Forskolin, 0.3–30 μ M , dose‐dependently increased caffeine‐stimulated CA release and 45 Ca efflux in the absence of Ca 2+ in the medium, and the effects were mimicked by dibutyryl cyclic AMP. These results suggest that cyclic AMP increases stimulation‐induced CA release by enhancing calcium uptake across the plasma membrane and/or altering calcium flux in an intracellular calcium store.