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Ca(2+) influx stimulated phospholipase C activity in bovine adrenal chromaffin cells: responses to K(+) depolarization and histamine

Authors :
Heather I. Saunders
Peter R. Dunkley
Emily L Roberts-Thomson
Susan Palmer
Stephen J. Bunn
David Powis
Source :
European journal of pharmacology. 398(2)
Publication Year :
2000

Abstract

The role of Ca(2+) influx in activating phospholipase C in bovine adrenal chromaffin cells has been investigated. Phospholipase C activity in response to K(+) depolarization (56 mM) was blocked by the L-type Ca(2+) channel antagonist nifedipine and partially inhibited by the omega-conotoxins GVIA and MVIIC. In contrast, phospholipase C activity in response to histamine receptor activation was unaffected by omega-conotoxin GVIA and partially inhibited by omega-conotoxin MVIIC or nifedipine. This response was however markedly inhibited by the non-selective Ca(2+) channel antagonists La(3+) or 1-[beta-[3-(4-Methoxyphenyl)propoxy]-4-methoyphenethyl]-H-imidazol e (SKF-96365). Despite this Ca(2+) dependence phospholipase C activity was not increased during periods of "capacitative" Ca(2+) inflow generated by histamine-, caffeine- or thapsigargin-mediated depletion of internal Ca(2+) stores. Thus, while Ca(2+) influx in response to K(+) depolarization or G-protein receptor activation can increase phospholipase C activity in these cells, in the latter case it appears to be ineffective unless there is concurrent agonist occupation of the receptor.

Details

ISSN :
00142999
Volume :
398
Issue :
2
Database :
OpenAIRE
Journal :
European journal of pharmacology
Accession number :
edsair.doi.dedup.....ae82eeb4563f93ce993436b38c9a1dbe