Amitraz depresses cardiovascular responses to bilateral carotid occlusion.
The ectoparasiticide amitraz stimulates alpha 2-adrenoceptors to produce side-effects such as bradycardia and hypotension. The actions of amitraz on baroreceptor reflex responses were evaluated in mongrel dogs by occlusion of both carotid arteries for 30-s periods. Incremental doses of amitraz given intravenously showed that doses of 60 micrograms/kg and above significantly depressed pressor responses to carotid occlusion. By comparison, 2 micrograms/kg amitraz given by intracisterna magna (i.c.m.) injection significantly depressed both blood pressure and heart rate responses. Pretreatment of dogs with i.c.m. yohimbine (30 micrograms/kg) prevented the depressant effects of amitraz on the reflex, but prazosin (20 micrograms/kg), in separate experiments, had no effect.
Reynoldson
J A
JA
School of Veterinary Studies, Murdoch University, Australia.
Cullen
L K
LK
D000818:Animals; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced; D002339:Carotid Arteries / Q000187:drug effects* / Q000502:physiology; D016893:Carotid Stenosis / Q000503:physiopathology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced; D007275:Injections, Intravenous / Q000662:veterinary; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D011224:Prazosin / Q000008:administration & dosage / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D014052:Toluidines / Q000008:administration & dosage / Q000494:pharmacology*; D015016:Yohimbine / Q000008:administration & dosage / Q000494:pharmacology
D007306:Insecticides; D011942:Receptors, Adrenergic, alpha; D014052:Toluidines; D015016:Yohimbine; C014983:amitraz; D011224:Prazosin