Epinephrine suppression of efferent activity of the adrenal nerve

Efferent nerve activity was recorded from nerve filaments dissected from the adrenal nerves in the rabbit before and after deafferentation of baroreceptors. Suppression of efferent activity of the adrenal nerve was observed following an injection of DL-epinephrine into the carotid artery. This suppression of adrenal nerve activity preceded the hypertension induced by epinephrine. An injection of lidocaine into the carotid artery caused a temporary suspension of the inhibitory effect of epinephrine. Adrenergic blocking agents also inhibited the suppressive effect of epinephrine. An injection of arterial blood collected during electrical stimulation of the splanchnic nerve reduced adrenal nerve activity. The present results suggest that catecholamines released from the adrenal medulla reflexly inhibit adrenal nerve activity through epinephrine-sensitive structure in the brain.