MODULATION OF VASCULAR ATP-DIPHOSPHOHYDROLASE BY FATTY-ACIDS

Endothelial cells (EC) possess several protective thromboregulatory me chanisms that may be perturbed by cell activation or injury. Vascular ATP-diphosphohydrolase (ATPDase) has been demonstrated on both aortic EC and smooth muscle cells and may play a key regulatory role in hemos tasis and platelet reactivity by converting extracellular ATP and ADP to AMP. We have examined the role of exogenous saturated or unsaturate d fatty acids in the modulation of EC associated ATPDase activity in v itro. EC growth was not dramatically influenced by supplementation wit h fatty acids whereas viability was enhanced by oleic, butyrate and ei cosapentaenoic acid. EC cultures supplemented with saturated or a mono unsaturated (oleic acid) fatty acid(s) had markedly increased ATPDase activity, whereas those exposed to polyunsaturated fatty acids showed substantive decreases. Exogenous oleic acid could also protect against the significant loss of ATPDase activity, following exposure to react ive oxygen intermediates in vitro. We conclude that endothelial ATPDas e activity may be regulated by exogenous fatty acids and that underlyi ng mechanisms include alterations in the nature of the phospholipid co mposition of EC membranes that influence responses to oxidative stress reactions.