Influence of clonidine upon sympathetic component of the carotid chemoreceptor reflex

The central influence of clonidine on the sympathetic component of carotid chemoreflex was verified in chloraloseurethane anaesthetised cats. The electrical stimulation of sinus nerve evoked only the excitatory responses in the sympathetic cardiac and renal nerve in the full range of stimulus strength. The excitatory response in the sympathetic renal nerve was completely depressed during the central cardiodepressor action of clonidine. Taking into account that the evoked excitatory responses in the sympathetic nerves were mainly the result of chemoreceptor carotid afferent fibre stimulation, it was concluded that clonidine depresses centrally carotid chemoreceptor reflex.