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Involvement of vascular endothelium in the potentiation of vasoconstrictor responses by neuropeptide Y

Although neuropeptide Y is not a potent vasoconstrictor in many vascular beds, nanomolar concentrations of this peptide can potentiate the response of isolated blood vessels to sympathetic stimulation or exogenous vasoconstrictors. Potentiation of the response to field stimulation was observed in superfused ring segments of rabbit ear artery or canine saphenous vein, provided that the endothelium was not mechanically damaged. The ability of neuropeptide Y to potentiate the constrictor response to noradrenaline in the ear artery was also dependent on the presence of an intact endothelium. The release of an endothelial-derived vasoconstrictor substance, as yet unidentified, by neuropeptide Y may explain its ability to potentiate the responses to both nerve stimulation and a variety of exogenous vasoconstrictors.