Reynoldson J A, Cullen L K
School of Veterinary Studies, Murdoch University, Australia.
J Vet Pharmacol Ther. 1996 Feb;19(1):22-6. doi: 10.1111/j.1365-2885.1996.tb00003.x.
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.
杀外寄生虫药双甲脒刺激α2 -肾上腺素能受体产生诸如心动过缓和低血压等副作用。通过对杂种犬双侧颈动脉进行30秒的阻断，评估了双甲脒对压力感受器反射反应的作用。静脉注射递增剂量的双甲脒表明，60微克/千克及以上的剂量显著抑制了对颈动脉阻断的升压反应。相比之下，通过小脑延髓池注射给予2微克/千克双甲脒显著抑制了血压和心率反应。用小脑延髓池注射育亨宾（30微克/千克）预处理犬可预防双甲脒对反射的抑制作用，但在单独的实验中，哌唑嗪（20微克/千克）没有效果。
