The effect of neuropeptide Y on the contractile response to field stimulation was examined in isolated blood vessels. Exogenous neuropeptide Y at a concentration of 100 nmol/l significantly potentiated the response to field stimulation in rabbit ear artery and canine saphenous vein. Administration of neuropeptide Y antiserum to tissues not previously exposed to neuropeptide Y significantly reduced the response to field stimulation; greater effects were observed in the rabbit ear artery than in the canine saphenous vein. Furthermore, this antiserum depressed the response to field stimulation in caudal arteries from spontaneously hypertensive rats (SHR), but not in those from normotensive Wistar-Kyoto rats (WKY). The depression by the anti-neuropeptide Y antibody did not appear to be produced by a non-specific mechanism, since antiserum against either thyrotrophin-releasing factor or platelet-derived growth factor did not affect the response to field stimulation. It is concluded that endogenous neuropeptide Y can contribute to the vascular contractile response to field stimulation, and that this contribution may be enhanced in hypertensive animals.
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