Substance P: Endothelial localization and pharmacology in the human ovarian vein

OBJECTIVE: To investigate the possible role of substance P as an endothelial factor in the local regulation of vascular tone in the human ovarian vein. METHODS: We performed immunolocalization of substance P in human ovarian venous endothelium in situ and in culture, and observed responses to substance P in preconstricted ring preparations of human ovarian vein in the presence of either the prostaglandin synthesis inhibitor indomethacin or the inhibitor of nitric oxide synthesis L-nitro arginine methyl ester (L-NAME), with and without luminal rubbing. RESULTS: Substance P was localized in a subpopulation of ovarian vein endothelial cells. Maximal relaxation induced by substance P was not significantly affected by indomethacin (10 mumol/L), but was reduced from 58.7% (95% confidence interval [CI] 41.3-76.1) in control experiments to 24.7% (95% CI 18.3-31.1) after luminal rubbing and to 32.3% (95% CI 19.8-44.8) after exposure to L-NAME (0.1 mmol/L) (P = .001). CONCLUSION: The localization of substance P in ovarian vein endothelium together with vasodilator effects mediated partially via the endothelium suggests that the peptide has a role in the local control of vascular tone in this vessel.