Reflex effects of renal afferents on the heart and kidney.

The reflex effects of renal afferents on the heart and kidney were studied in dogs anesthetized with pentobarbital sodium. Renal afferent and efferent nerve activity recorded from the renal nerves during occlusion of a single renal vein resulted in increases in nontonically firing renal afferent activity and decreases in tonically firing afferent activity. Renal efferent nerve activity from the contralateral kidney was always inhibited during single renal vein occlusion. This decrease in nerve activity was associated with a decrease in renal vascular resistance. Denervation of the congested kidney eliminated the reflex changes in renal vascular resistance. Cardiopulmonary sympathetic efferent nerve activity from the ansae subclavia was always reflexly inhibited by single renal vein occlusion. Although heart rate and left ventricular contractile force were not altered during renal vein occlusion, right ventricular contractile force decreased by -6 to -25%. This reflex decrease in contractile force was eliminated by denervation of the congested kidney. These studies demonstrate that renal afferents, activated by increases in renal venous pressure, can reflexly inhibit contralateral renal and cardiopulmonary sympathetic efferent nerve activity, decrease contralateral renal vascular resistance, and decrease right ventricular contractile force, without altering heart rate.