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Phorbol Ester‐Induced Upregulation of Angiotensin II Receptors in Neuronal Cultures Is Potentiated by a Calcium Ionophore
Author(s) -
Sumners Colin,
Rueth Susan M.,
Myers Linda M.,
Kalberg Christopher J.,
Crews Fulton T.,
Raizada Mohan K.
Publication year - 1988
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.1471-4159.1988.tb04849.x
Subject(s) - protein kinase c , angiotensin ii , angiotensin receptor , receptor , calcium , medicine , endocrinology , chemistry , phorbol , downregulation and upregulation , biology , signal transduction , biochemistry , gene
Previous studies have suggested that protein ki‐nase C is important in the regulation of angiotensin II receptors in neuronal cultures, because the C‐kinase agonists, phorbol esters, are able to increase the number of these receptors. In the present study, we have further investigated the role of protein kinase C in angiotensin II receptor regulation. This enzyme is calcium dependent, and so we investigated the effects of A23187, a calcium ionophore, on phorbol ester‐stimulated and basal angiotensin II receptor regulation. A23187, at concentrations that increased 45 Ca 2+ influx, caused a dose‐dependent potentiation of phorbol‐12‐myristate‐13‐acetate (TPA)‐stimulated upregulation of angiotensin II receptors. This potentiation by A23187 was a further increase in angiotensin II receptor number and was abolished in calcium‐free medium. In the absence of TPA, A23187 caused a decrease in angiotensin II receptor number, an effect not observed in calcium‐free medium. The results suggest at least two pathways for angiotensin II receptor regulation in neuronal cells: (a) by calcium‐dependent protein kinase C and (b) via an influx of calcium into the cell.