Effect of alinidine (St 567) on sympathetic and vagal activities

A depressor effect on spontaneous preganglionic sympathetic discharge rate could be shown in anaesthetized, debuffered cats after i.v.-injection of 2.5 mg/kg alinidine. This effect developed gradually and did not parallel the marked bradycardia which was of prompt onset. In anaesthetized dogs with beta-adrenoceptors blocked, alinidine (2.5 mg/kg i.v. or 0.5 mg/kg intracisternally) proved to be without effect on vagally mediated reflex bradycardia. This reaction pattern (inhibition of sympathetic discharges, no effect on vagal baroreflex activity) differentiates alinidine from clonidine-like substances, which are known to decrease sympathetic tone and to increase vagally mediated reflex bradycardia.