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The Adenosine Analogue N 6 ‐L‐Phenylisopropyladenosine Inhibits Catecholamine Secretion from Bovine Adrenal Medulla Cells by Inhibiting Calcium Influx
Author(s) -
Chern YiJuang,
Bott Marga,
Chu PoJu,
Lin YiJen,
Kao LungSen,
Westhead Edward W.
Publication year - 1992
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.1471-4159.1992.tb08453.x
Subject(s) - medicine , endocrinology , adenosine , catecholamine , adrenal medulla , secretion , calcium , biology , veratridine , stimulation , chemistry , sodium , sodium channel , organic chemistry
We reported earlier that adenine nucleotides and adenosine inhibit acetylcholine‐induced catecholamine secretion from bovine adrenal medulla chromaffin cells. In this article, we used an adenosine analogue, N 6 ‐L‐phenyliso‐propyladenosine (PIA), to study the mechanism underlying inhibition of catecholamine secretion by adenosine. PIA inhibits secretion induced by a nicotinic agonist, 1,1‐di‐methyl‐4‐phenylpiperazinium, or by elevated external K + . The half‐maximal effect on 1,1‐dimethyl‐4‐phenylpiperazinium‐induced secretion occurred at ∼5 ± 10 ‐ ‐ 5 M . The inhibition is immediate and reversible. Fura‐2 measurements of cytosolic free Ca 2+ indicate that PIA inhibits Ca 2+ elevation caused by stimulation; measurements of 45 Ca 2+ influx show that PIA inhibits uptake of Ca 2+ . PIA does not inhibit calcium‐evoked secretion from digitonin‐permeabilized cells, nor does PIA cause any significant change in the dependence of catecholamine secretion on calcium concentration. These data suggest that inhibition by PIA occurs at the level of the voltage‐sensitive calcium channel.