Endothelin-1-evoked arachidonic acid release: a ca+2-dependent
pathway.
Wu-Wong, Jinshyun R., Brian D. Dayton, and Terry J. Opgenorth.
Pharmaceutical Products Division, Abbott Laboratories, Abbott Park,
IL 60064, U.S.A.
APStracts 3:0069C, 1996.
Endothelins (ET) are potent vasoconstricting peptides with 21-amino
acid residues. ET-1 stimulates arachidonic acid (AA) release in human
pericardial smooth muscle cells (HPSMC), primarily mediated through
the ETA receptor. Manoalide, an inhibitor for phospholipase A2,
inhibited the ET-1-evoked response by 50% at 1 [mu]M. RHC 80267, an
inhibitor for diacylglycerol lipase, did not have a significant
effect. The calcium ionophore A23187 at 2 [mu]M greatly stimulated AA
release in the presence of extracellular Ca+2. ET-1 (10 nM) evoked a
robust Ca+2 response. The intracellular Ca+2 concentration reached a
peak after 10 sec, and gradually decreased to a new plateau level in
the presence of extracellular Ca+2. ET-1-evoked AA release closely
followed the change in the intracellular Ca+2 concentration. Removal
of extracellular Ca+2 or treating cells with 250 [mu]M MAPTAM (an
intracellular Ca+2 chelator) greatly reduced ET-1-stimulated AA
release. Protein kinase C (PKC) inhibitors, staurosporine (1 [mu]M)
and chelerythrine chloride (2.5 [mu]M), inhibited ET-1-evoked AA
release by 70%. Phorbol 12-myristate 13-acetate, a PKC activator,
potentiated the effect of ET on AA release. The data suggest that the
effect of ET on AA release in HPSMC is via phospholipase A2 which is
modulated by Ca+2 and PKC.
Received 20 October 1995; accepted in final form 26 February
1996.
APS Manuscript Number C640-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96