Thromboxane A(2)-induced phosphatidylcholine hydrolysis in porcine vascular smooth muscle cells

The effect of 9,11-epithio-11,12-methanothromboxane A(2) (STA(2)), a thromb oxane A(2) receptor agonist, on phosphatidylcholine hydrolysis was examined in porcine vascular smooth muscle cells. Although STA(2) stimulated diacyl glycerol production in a concentration-dependent manner, it only caused a s light accumulation of [H-3]phosphatidylethanol in the presence of 0.5% etha nol, reflecting its weak stimulation of phosphatidylcholine-specific phosph olipase D. STA(2)-induced diacylglycerol production was potently and concen tration dependently inhibited by potassium tricyclo-[5.2.1.0(2.6)]-decyl-(9 [8])-xanthogenate (D609), an inhibitor of phosphatidylcholine-specific phos pholipase C. These results suggest that the thromboxane A(2) receptor in va scular smooth muscles is functionally coupled to phosphatidylcholine-specif ic phospholipase C to yield diacylglycerol. (C) 1999 Elsevier Science B.V. All rights reserved.