Reflex Changes in Sympathetic Activity and Arterial Blood Pressure Evoked by Afferent Stimulation of the Renal Nerve

The effects of afferent stimulation of renal nerves on efferent sympathetic activity and systemic blood pressure were studied in anesthetized rabbits. In most animals, afferent impulses pro duced reduction or abolition of sympathetic activity and a fall in blood pressure. High fre quencies of stimulation (20–30 pulses/sec or more) caused a more marked and long‐lasting depression of efferent activity and blood pressure than low frequencies. The highest sensitivity of blood pressure to variations in stimulation frequency was found in the range of 1–10 pulseslsec. Stimulation of the renal afferents had qualitatively the same effect on sympathetic activity and blood pressure as aortic nerve stimulation, but for the aortic nerve, higher stimu lation frequencies were required to obtain the same reduction in blood pressure. It is con cluded that afferent activity in renal nerves has a predominantly inhibitory effect on vasomotor activity, resulting in a fall in blood pressure.