title: The antagonistic effects of atipamezole and yohimbine on stress-related neurohormonal and metabolic responses induced by medetomidine in dogs.
abstract: This study aimed to compare the antagonistic effects of atipamezole (40,120, and 320 microg/kg, IM), yohimbine (110 microg/kg, IM), and saline on neurohormonal and metabolic responses induced by medetomidine (20 microg/kg, IM). Five beagle dogs were used in each of the 5 experimental groups in randomized order. Blood samples were taken for 6 h. Medetomidine significantly decreased norepinephrine, epinephrine, insulin, and nonesterified fatty acid levels, and increased plasma glucose levels. Both atipamezole and yohimbine antagonized these effects. The reversal effect of atipamezole was dose-dependency, except on epinephrine. Yohimbine caused prolonged increases in plasma norepinephrine and insulin levels compared to atipamezole, possibly because of its longer half-life elimination. Only yohimbine increased the cortisol levels. Neither glucagon nor lactate levels changed significantly. Based on these findings, when medetomidine-induced sedation is antagonized in dogs, we recommend using atipamezole IM, from 2- to 6-fold the dose of medetomidine, unless otherwise indicated.
authors.affiliation: Department of Veterinary Internal Medicine, Faculty of Agriculture, Tottori University, Koyama-Minami 4-101, Tottori 680-8553, Japan.
authors.forename: T D
authors.initials: TD
authors.lastname: Ambrisko
authors.forename: Y
authors.initials: Y
authors.lastname: Hikasa
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D004285:Dogs / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004837:Epinephrine / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D006993:Hypnotics and Sedatives / Q000037:antagonists & inhibitors*; D007093:Imidazoles / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D020926:Medetomidine / Q000037:antagonists & inhibitors*; D009638:Norepinephrine / Q000097:blood; D011897:Random Allocation; D013312:Stress, Physiological / Q000188:drug therapy / Q000378:metabolism / Q000662:veterinary; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D005230:Fatty Acids, Nonesterified; D006993:Hypnotics and Sedatives; D007093:Imidazoles; D007328:Insulin; C050701:atipamezole; D015016:Yohimbine; D020926:Medetomidine; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine