Aim Using cultured porcine endothelial cells withsensitive quantitative methods, this study aims to in-vestigate the regulating effect of neuropeptide Y (NPY)and vasoactive intestinal peptide (VIP) on endothelialfunctions. The work should be optional for betterunderstanding the possible role of neurocrine factors inatherogenesis.Methods A specific and sensitive diazotization assayand radioimmunoreactive analysis were used respec-tively to measure the release of nitric oxide (NO) andendothelin (ET) from porcine aorta endothelial cellsgrown in culture.Results NPY and VIP could affect the release of NO and ET from cultured endothelial cells. Underthe influence of NPY, the content of NO2 and ET inendothelium-conditioned medium were increased with NPY concentration (P<0. 053 , but the increase of ETwas larger than NO in NPY group. In VIP group,the content of ET in endothelium-conditioned medium was decreased with VIP concentration (P<0. 05 ).Conclusion The first , NPY may stimulate culturedporcine aorta endothelial cells to release the NO and ET, but the increase of ET is more than NO. Thesecond, VIP may inhibit the secretion of ET from cul-tured endothelial cells.