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Regional heterogeneity in the contractile and potentiating effects of neuropeptide Y in rat isolated coronary arteries: modulatory action of the endothelium
Author(s) -
Prieto Dolores,
Benedito Sara,
Simonsen Ulf,
Nyborg Niels C. Berg
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb12245.x
Subject(s) - neuropeptide y receptor , coronary arteries , medicine , contraction (grammar) , endocrinology , endothelium , circulatory system , chemistry , artery , neuropeptide , receptor
1 Neuropeptide Y (NPY) induced a concentration‐dependent contraction of isolated rings of proximal epicardial (PC) and distal intramural (DC) coronary arteries of the rat, with an EC 50 of ca. 1 × 10 −7 m . The NPY‐induced contraction at 3 × 10 −7 m was significantly smaller in PC than DC arteries: 34% vs. 55% of the 125 m m K + ‐induced response, respectively. 2 NPY (2 × 10 −8 m ) increased the sensitivity to noradrenaline (NA) and 5‐hydroxytryptamine (5‐HT) more in PC (4.2 and 2.8 fold, respectively) than in DC arteries (2.2 and 1.4 fold, respectively). The maximal contractile response to NA and 5‐HT was increased more in DC (43% and 29%, respectively) than in PC arteries (20% and 12%, respectively). 3 Removal of the endothelium increased the sensitivity and maximal response to NPY as well as the spontaneous myogenic tone in PC but not in DC arteries. NPY had no relaxing effect on PC and DC arteries submaximally contracted with 10 −6 m prostaglandin F 2α , suggesting that spontaneous rather than stimulated release of endothelium‐derived relaxing factor (EDRF) depresses the contractile action of NPY in PC arteries. 4 The results indicate a heterogeneity in the contractile and potentiating action of NPY in rat coronary arteries depending on size or location in the coronary circulation.