TY - JOUR T1 - Neuropeptide Y-Mediated Pressor Responses Following High-Frequency Stimulation of the Rat Sympathetic Nervous System JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 291 LP - 296 VL - 281 IS - 1 AU - Brian Kennedy AU - Gregory H. Shen AU - Michael G. Ziegler Y1 - 1997/04/01 UR - http://jpet.aspetjournals.org/content/281/1/291.abstract N2 - Neuropeptide Y (NPY) is a potent pressor agent that is stored in the sympathetic nerves. In several species, NPY release is augmented when sympathetic impulse frequencies increase. We investigated the extent to which NPY contributes to the pressor response to high- and low-frequency electrical stimulation. Rats were pithed, and the sympathetic trunk was stimulated at either 20 or 3 Hz in the presence or absence of antagonists of NPY and alpha andbeta adrenergic receptors. The 20-Hz stimulation raised plasma NPY levels, but the 3-Hz stimulation did not. The 20-Hz stimulation caused marked pressor responses that were maintained for several minutes after the end of stimulation regardless of whether rats were pretreated with adrenergic blockers. The NPY antagonists BIBP 3226 and 1229U91 reduced the size of the pressor response that followed 20 Hz stimulation by >50%. The rapid blood pressure spikes that occur during electrical stimulation are attenuated by alphaadrenergic but not by NPY antagonists. There is a prolonged pressor response after high-frequency stimulation of the sympathetic trunk in pithed rats that begins after 1 to 2 min of stimulation and lasts ∼10 min after the end of stimulation. At least half of this pressor response is mediated by NPY. The American Society for Pharmacology and Experimental Therapeutics ER -