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Impacts and mechanisms of dexmedetomidine HCl on heart rate in rabbit with bilateral vagotomy or sympathectomy

Jie Wu, Enjun Lei, Jiegang Zhou, Doudou Zhao

The aim of the current study was to investigate the impacts of dexmedetomidine HCl (Dex) on the heart rate in the rabbits with bilateral vagotomy or sympathectomy. 30 healthy male New Zealand white rabbits, weighing 2~2.5 kg, were randomly divided into three groups (n=10): the experimental group (group V) was abscised the vagus nerves, the de-sympathetic nerve group (group S), and the control group (group C, with autonomic nerves preserved). After being anesthetized, group V and S were performed bilateral vagotomy and sympathectomy, respectively, but group C were retained the bilateral autonomic nerves. The three groups were all intravenously infused Dex 3 μg/kg within 10 min. The heart rates (HR) and the arterial acetylcholine (Ach) contents in the three groups were recorded at different time points (after anesthesia (T0), after neurectomy (T1), and 10 min after Dex infusion (T2). Group V and S significantly decreased HR while significantly increased Ach at T2 (p<0.05). Intravenous injection of Dex can reduce HR in rabbits; after cutting off the bilateral vagus nerves or sympathetic nerves, the release of Ach is increased, so HR in rabbits is further declined.