MECHANISM OF ENDOTHELIUM-DEPENDENT VASORELAXATION EVOKED BY LYSOPHOSPHATIDYLCHOLINE

Vasorelaxation induced by lysophosphatidylcholine (LPC) and platelet a ctivating factor (PAF) was examined in rings isolated from rat aorta a nd mesenteric artery. LPC caused dose-dependent vasodilatation, which was sensitive to CV-6209, a PAF antagonist, and N-G-monomethyl-L-argin ine, a nitric oxide synthase inhibitor, but insensitive to indomethaci n. PAF (10(-7) M) caused a tachyphylactic effect in mesenteric artery, but no tachyphylactic effect was demonstrated with LPC. Vasorelaxatio n patterns with LPC differed from those with PAF in the rat mesenteric artery. These results suggest that LPC-induced vasorelaxation may inv olve increased nitric oxide production mediated by the PAF receptor pa thway, another receptor pathway possibly blocked by CV-6209, or PAF it self produced in endothelial cells in response to LPC.