title: Antagonism of xylazine and ketamine anesthesia by 4-aminopyridine and yohimbine in geldings.
abstract: Thirty-six fasted, mixed horse breed geldings (6 groups of 6 animals each) were anesthetized with xylazine and ketamine, and when maximally sedated, were given 1 of the following antagonists: saline solution, 4-aminopyridine (4-AP), small-dose yohimbine, large-dose yohimbine, 4-AP plus low-dose yohimbine, or 4-AP plus high-dose yohimbine. Measured data included mean standing time (MST), heart rate, respiratory rate, rectal temperature, and mean total recovery time ( MTRT ). Emergence phenomena were also observed and recorded as smooth, fairly smooth, fairly rough, or rough. Groups given 4-AP alone, small-dose yohimbine alone, or large-dose yohimbine alone produced a significant (P less than 0.05) decrease in MST (9.9 +/- 1.6 minutes, 11.3 +/- 1.7 minutes, and 10.6 +/- 2.3 minutes, respectively) compared with that in the saline control group (24.3 +/- 9.2 minutes). The MTRT were not significantly (P greater than 0.05) different (47.2 +/- 10 minutes, 90.4 +/- 15.1 minutes, and 83.2 +/- 23 minutes, respectively) from control values (66.2 +/- 13.4 minutes). When the antagonists were combined, 4-AP plus small-dose yohimbine and 4-AP plus large-dose yohimbine produced significant (P less than 0.05) decreases (10.3 +/- 2 minutes and 8.3 +/- 2.6 minutes, respectively) in MST compared with that of saline controls. The MTRT was significantly longer in the combined antagonist group (4-AP + small-dose yohimbine--131.8 +/- 28.9 minutes; 4-AP + large-dose yohimbine--131.3 +/- 19.4 minutes) compared with that of control or any antagonist alone.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology*; D000771:Anesthesia, Intravenous / Q000379:methods / Q000662:veterinary*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D002415:Cats; D006339:Heart Rate / Q000187:drug effects; D006736:Horses / Q000502:physiology*; D007649:Ketamine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008297:Male; D012119:Respiration / Q000187:drug effects; D013843:Thiazines / Q000037:antagonists & inhibitors*; D014991:Xylazine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D000631:Aminopyridines; D013843:Thiazines; D014991:Xylazine; D015016:Yohimbine; D007649:Ketamine; D015761:4-Aminopyridine