NEUROGENICALLY EVOKED CEREBRAL-ARTERY CONSTRICTION IS MEDIATED BY NEUROPEPTIDE-Y

We examined the proposal that neuropeptide Y (NPY) released from nerve endings constricts cerebral arteries. Neurogenic vasoconstriction of rabbit basilar arteries is of adrenergic origin but is resistant to bl ockade by classical alpha-adrenoceptor antagonists. Tetrodotoxin-sensi tive contractions of the rabbit basilar artery were elicited by transm ural stimulation of nerves. The contractions were inhibited by incubat ion of tissues with an antiserum to NPY (0.32 mu L undiluted immune se rum/mL); addition of prazosin (0.1 mu M) did not further attenuate the nerve-mediated contraction. The antiserum to NPY also antagonized vas oconstriction due to exogenously administered NPY and was without effe ct on responses due to histamine or angiotensin. Our results indicate that neurogenic vasoconstriction of the rabbit basilar artery is large ly due to the release of NPY and that it is unlikely that other vasoco nstrictors contribute significantly to the increased tone.