O40	Activation of phospholipase D by angiotensin II in HUVECS and HMVECS.
S.McHarg, J.Whatmore, A.Shore, for Institute of Clinical and Biomedical Science
Peninsula Medical School, Exeter, GB.

Phospholipase D (PLD) is an intracellular signalling enzyme, stimulated by numerous agonists to produce the second messenger phosphatidic acid. PLD is known to be highly important in both physiological and pathophysiological signalling pathways, such as those involved in the progression of vascular disease. In such diseases, the vasculature can have impaired responses to the vasoconstrictor angiotensin II (A-II). It has previously been shown that A-II activates PLD in human vascular smooth muscle cells, but there is no evidence for such activation in the endothelium. This study aims to establish if PLD is activated by A-II in both human umbilical vein endothelial cells (HUVECs) and human microvascular endothelial cells (HMVECs). [3H] myristic acid labeled human endothelial cells were treated with varying doses of angiotensin II (100pM – 1µM) for 20 minutes in the presence of 0.5% ethanol. PLD activity was assessed by quantitation of 3H phosphatidylethanol. 1nM A-II activated PLD in both HUVECs and HMVECs, causing a mean increase of 153 ± 39% (p<0.002, n=6) and 177 ± 20 (p<0.037, n=3) (control values = 100%) respectively. Thus the data support a role for PLD activation in the endothelial effects of A-II in both the macro and microvascular circulation.

Copyright © 2005 S. Karger AG, Basel. Any further use of this abstract requires written permission from the publisher.