LYSOPHOSPHATIDYLCHOLINE-INDUCED VASCULAR RELAXATION AND PRODUCTION OFCGMP ARE MEDIATED BY ENDOTHELIUM-DERIVED RELAXING FACTOR

Endothelial cells produce powerful vasorelaxant substances, among them an endothelium-derived relaxing factor that is believed to be nitric oxide. It relaxes vascular smooth muscle via activation of guanylate c yclase and a subsequent rise in cyclic GMP level. Lysophosphatidylchol ine is a potent endothelium-dependent vascular smooth muscle relaxant. Its action, similar to that of endothelium-derived relaxing factor, m ediates an increase of cGMP in smooth muscle cells. The experiments re ported here demonstrate that inhibitors of nitric oxide formation, suc h as N-omega-nitro-L-arginine and its methyl ester, inhibit relaxation and cyclic GMP formation by lysophosphatidylcholine in bovine pulmona ry artery strips with intact endothelium in a dos-dependent manner. N- omega-Nitro-D-arginine methyl ester does not inhibit relaxation; L-arg inine, but not D-arginine, reverses the effect of N-omega-nitro-L-argi nine and its methyl ester. It is concluded that lysophosphatidylcholin e-induced endothelium-dependent vasorelaxation is endothelium-derived relaxing factor-mediated.