title: Urotensin II inhibits carotid sinus baroreflex in anesthetized male rats.
abstract: OBJECTIVE
  To study the effects of urotensin II (UII) on the carotid sinus baroreflex (CSB).
  
  
  METHODS
  The functional curve of carotid sinus baroreflex was measured by recording changes in arterial pressure in anesthetized male rats with perfused isolated carotid sinus.
  
  
  RESULTS
  UII at the concentration of 3 nmol/L had no effect on the CSB, while at the concentration of 30, 300 and 3000 nmol/L inhibited the CSB, shifting the functional curve of the baroreflex upward and to the right. There was a marked decrease in peak slope and reflex decrease in blood pressure. These effects of UII were concentration-dependent. Pretreatment with verapamil (an antagonist of the L-type calcium channel, 10 micromol/L) partially eliminated the above effects of UII (300 nmol/L) on the CSB. Pretreatment with BIM-23127 (3 micromol/L), an antagonist of human and rat UII receptors, abolished the actions of UII on the CSB. Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME) 100 micromol/L did not affect the inhibitory effects of UII (300 nmol/L) on the CSB.
  
  
  CONCLUSIONS
  These data suggest that UII exerts an inhibitory action on the isolated CSB. Such an action of UII is predominantly mediated by the UII receptors in vascular smooth muscles, resulting in the opening of L-type calcium channels.
authors.affiliation: Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China. wuym@hebmu.edu.cn
authors.forename: Yu-ming
authors.initials: YM
authors.lastname: Wu
authors.forename: Hong-mei
authors.initials: HM
authors.lastname: Xue
authors.forename: Lin
authors.initials: L
authors.lastname: Xiao
authors.forename: Rui-rong
authors.initials: RR
authors.lastname: He
mesh_terms: D000758:Anesthesia; D000818:Animals; D017704:Baroreflex / Q000187:drug effects*; D002346:Carotid Sinus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014579:Urotensins / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: C092829:BIM 23127; D010456:Peptides, Cyclic; D014579:Urotensins; C029677:urotensin II; D014700:Verapamil; D019331:NG-Nitroarginine Methyl Ester