Afferent renal nerve stimulation excites supraoptic vasopressin neurons

Single-unit recording experiments were performed in pentobarbital-anesthetized rats to investigate the effects of afferent renal nerve (ARN) stimulation on the activity of neurosecretory vasopressin cells of the supraoptic nucleus (SON). Neurosecretory SON cells were identified by antidromic invasion from the neurohypophysis and classified either as vasopressin (AVP) or oxytocin (OXY) secreting on the basis of their spontaneous activity patterns and response to activation of arterial baroreceptors. Fifty-three spontaneously active units were identified bilaterally in the SON: 40 putative AVP and 13 putative OXY neurons. Most putative AVP neurons (14/14 contralateral, 18/26 ipsilateral) were excited by ARN stimulation (mean onset latency 189 +/- 5 ms, mean response duration 237 +/- 17 ms). In contrast, ARN stimulation had no effect on the firing frequency of the 13 putative OXY neurons. These data indicate that sensory information originating in the kidney selectively alters the activity of SON AVP neurons and suggest that afferent information from the kidney is important in the coordination of neural and hormonal activity concerned with body fluid balance and the regulation of arterial pressure.