Open AccessAltered Intra- and Extraluminal Effects of 5-Hydroxytryptamine in Hypertensive Mesenteric Resistance Arteries
Author(s) -
Yasuaki Dohi,
Thomas F. Lüscher
Publication year - 1991
Publication title -
journal of cardiovascular pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 100
eISSN - 1533-4023
pISSN - 0160-2446
DOI - 10.1097/00005344-199108000-00015
Subject(s) - ketanserin , mesenteric arteries , endothelium , contraction (grammar) , medicine , endocrinology , serotonin , 5 ht receptor , agonist , blood vessel , receptor , vasodilation , anatomy , artery
Vasoconstrictor responses to intraluminal and extraluminal 5-hydroxytryptamine (5-HT) were studied in isolated mesenteric resistance arteries of Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Third-order branches of mesenteric arteries were dissected free and mounted on glass cannulae in organ chambers. Changes in intraluminal diameter of the perfused and pressurized vessels were measured. Extraluminal 5-HT (10(-8)-10(-4)M) evoked concentration-dependent contractions that were augmented after removal of the endothelium. The sensitivity of arteries without but not of those with endothelium to 5-HT was increased in SHRs compared to WKY rats. The pA2 value for ketanserin using 5-HT as an agonist was identical in WKY rats and SHRs. The slope of the Schild plots did not significantly differ from 1. Intraluminal 5-HT caused smaller contractions in arteries with endothelium than extraluminal 5-HT. After endothelial removal, the contractions to intraluminal 5-HT were increased. The contraction induced by intraluminal 5-HT in arteries with endothelium was greater in SHRs than WKY rats. Thus, contractile responses to 5-HT are mediated by homogeneous 5-HT2 receptors in rat mesenteric resistance arteries. In SHRs, the affinity of the receptor to 5-HT is not altered. The sensitivity of vascular smooth muscle to 5-HT is increased and the protective role of the endothelium against intraluminal 5-HT is decreased in SHRs.