Influence of 2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride on cardio-inhibitory vagal fibres

Neural activity of cardio-inhibitory vagal fibres was recorded in anaesthetized cats. The discharges increased when the blood pressure rose after injection of an alpha-adrenergic substance such a norepinephrine or 2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride (St 91). After transection of the afferent baroreceptor nerves neither norepinephrine nor St 91 influenced neural activity. These findings show that the increase in neural activity is of reflex origin. An influence of St 91 on central parasympathetic structures could not be demonstrated.