title: The effects of jingsongling, a xylazine analog, on mean arterial blood pressure and heart rate in dogs--influences of yohimbine, tolazoline, prazosin, and atropine.
abstract: The effects of jingsongling (JSL) and xylazine on heart rate (HR) and mean arterial pressure (MAP) were studied in five conscious male dogs. An i.v. injection of xylazine (1 mg/kg) caused a bradycardia, an initial hypertension, and a subsequent hypotension. An i.v. injection of JSL (1 mg/kg) caused a bradycardia and a 20-min hypertension without a subsequent hypotension. Atropine sulfate (45 micrograms/kg, i.v.) increased HR for 30 min without changing MAP, and antagonized JSL-induced bradycardia for at least 60 min. There was a subsequent rebound bradycardia. Atropine sulfate potentiated JSL-induced hypertension in both magnitude and duration. Yohimbine (0.1 mg/kg, i.v.), an alpha 2-adrenoceptor antagonist, increased HR and MAP for 110 and 70 min, respectively. Yohimbine not only failed to potentiate but even reversed the pressor effect of JSL in a dose-dependent manner. Yohimbine also caused a dose-dependent reversal of JSL-induced bradycardia. Tolazoline (5 mg/kg, i.v.), a nonselective alpha-adrenoceptor antagonist, increased MAP for 20 min without changing HR. Tolazoline also reversed JSL-induced hypertension and bradycardia. Prazosin (1 mg/kg), an alpha 1-adrenoceptor antagonist, decreased MAP and increased HR for at least 110 min. Prazosin reversed JSL-induced hypertension but failed to affect JSL-induced bradycardia. These results indicated that: (1) JSL-induced bradycardia and hypertension are mediated by alpha 2-adrenoceptors; (2) yohimbine and tolazoline may be useful in antagonizing these untoward reactions associated with JSL administration, whereas prazosin and atropine were not found to be beneficial in this regard.
authors: Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Iowa State University, Ames 50011.
authors: W H
authors: WH
authors: Hsu
authors: Y F
authors: YF
authors: Rong
authors: F B
authors: FB
authors: Hembrough
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D015394:Molecular Structure; D011224:Prazosin / Q000494:pharmacology; D013843:Thiazines / Q000494:pharmacology*; D013844:Thiazoles / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014043:Tolazoline / Q000494:pharmacology; D014991:Xylazine / Q000031:analogs & derivatives / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D013843:Thiazines; D013844:Thiazoles; C061661:jingsongling; D014991:Xylazine; D015016:Yohimbine; D001285:Atropine; D014043:Tolazoline; D011224:Prazosin