title: Endothelium-dependent relaxation in resistance vessels from the spontaneously hypertensive rats.
abstract: The endothelium-dependent vasodilator acetylcholine was used to observe relaxation responses of noradrenaline-contracted mesenteric resistance vessels from 3-, 6-, 12- and 18-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Relaxation responses were greater than normal in the 3-week-old SHR but the pattern of response was different in the 6-18-week-old SHR compared with the WKY. In these older animals, low concentrations of acetylcholine relaxed SHR and WKY vessels to a similar extent, but high concentrations (greater than 10(-7) mol/l) caused the partially relaxed vessels to contract again. Indomethacin enhanced relaxation in the 12-week-old SHR and reduced the difference between the SHR and WKY. The reduction in acetylcholine-induced, endothelium-dependent relaxation in SHR suggested that a functional change occurred, causing the vessels to release a vasoconstrictor factor that opposes the action of endothelium-derived relaxing factor.
authors.affiliation: Department of Medicine, Leicester Royal Infirmary, UK.
authors.forename: P A
authors.initials: PA
authors.lastname: Watt
authors.forename: H
authors.initials: H
authors.lastname: Thurston
mesh_terms: D000109:Acetylcholine / Q000493:pharmacokinetics*; D000367:Age Factors; D000818:Animals; D001808:Blood Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D000109:Acetylcholine