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Role of inward K + channel located at carrot plasma membrane in signal cross‐talking of cAMP with Ca 2+ cascade
Author(s) -
Kurosaki Fumiya
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00403-1
Subject(s) - ionophore , chemistry , valinomycin , forskolin , biophysics , extracellular , membrane , channel blocker , vesicle , tetraethylammonium , stimulation , ion transporter , membrane potential , ion channel , calcium , biochemistry , potassium , endocrinology , biology , in vitro , organic chemistry , receptor
Treatment of cultured carrot cells with dibutyryl cAMP or forskolin resulted in the appreciable decrease in extracellular K + concentration. This decrease was found to be transient and the concentration of the ion in the culture medium restored to the original level within few minutes. The cAMP‐induced decrease in K + level in the medium was almost completely inhibited when carrot cells were incubated in the presence of K + channel blockers, CsCl and tetraethylammonium chloride. Appreciable amounts of 45 Ca 2+ were discharged from 45 Ca 2+ ‐loaded inside‐out vesicles of carrot plasma membrane by the stimulation with cAMP, however, the release of the ion was significantly inhibited in the presence of the K + channel blockers. The release of 45 Ca 2+ from the vesicles was also observed when K + current was evoked with an ionophore, valinomycin, even in the absence of cAMP. These results suggest that the gating of some of the inward K + channels located at plasma membrane of cultured carrot cells is controlled by cytoplasmic concentration of cAMP and the inward K + current across the plasma membrane induced by the nucleotide elicits Ca 2+ influx into the cells possibly by the activation of voltage‐dependent Ca 2+ channels.