Myocardial electrophysiological effects of neuropeptide Y in dogs.
Neuropeptide Y (NPY) exerts coronary vasomotor and inotropic effects on the canine heart. To test whether NPY also exerts regional myocardial electrophysiological effects, dose-response and time course changes resulting from intravenous and regional intracoronary infusions of NPY were obtained in 14 alpha-chloralose-anesthetized dogs. Under constant ventricular pacing, activation (A), recovery (R), and A-R interval (ARI) maps were constructed from multiplexed unipolar surface electrograms recorded simultaneously from 64 sites within a 1.6 x 1.6-cm left ventricular region. Effects were compared with those of vasoactive intestinal peptide (VIP) infusions and supramaximal left ansae subclaviae sympathetic nerve stimulation (SNS). The main finding was a uniform shortening of ARI, which reached a maximum of 8.7 +/- 1.2 ms, or 7% of control (P < 0.001), at about three times the baseline NPY plasma concentration (21.6 +/- 1.9 pg/ml). This effect decayed slowly (> 15 min) along with NPY plasma levels. The effect of similar VIP infusions and of SNS was 11%. Thus, compared with the previously identified maximal effect of adenylate cyclase activation (20%), exogenous NPY exerts a moderate but markedly sustained ventricular myocardial electrophysiological effect, which reaches maximum in relatively low plasma concentrations.
Kralios
F A
FA
Nora Eccles Harrison Cardiovascular Research and Training Institute, Department of Internal Medicine (Cardiology), University of Utah School of Medicine, Salt Lake City, USA.
Anderson
F L
FL
Hanson
G R
GR
Kralios
A C
AC
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D006321:Heart / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000502:physiology; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects
D009478:Neuropeptide Y; D014660:Vasoactive Intestinal Peptide