Inhibitory effect of the contralateral kidney on the renal pressor reflex evoked by ipsilateral renal artery stenosis.

We previously identified a sympathoexcitatory pressor reflex that is evoked by acute (90 min) unilateral renal artery stenosis (RST). The reflex is strongly expressed in conscious rats when the renin-angiotensin system and baroreflexes are diminished by captopril and sinoaortic denervation, and is eliminated by denervation of the stenosed kidney. In the present study, dorsal rhizotomy inhibited the reflex, establishing the role of afferent renal nerves (ARN). During sustained (10 h) RST, the reflex reversed within 4 hours after onset of RST, but persisted after removal of the contralateral kidney. Hematocrit measurements did not support pressure diuresis as a mechanism for inhibition by the contralateral kidney. Other studies suggest that ARN signals and/or release of antihypertensive renomedullary lipid from the contralateral kidney are not involved in inhibition of the reflex. These data suggest that the contralateral kidney can oppose, at least acutely by an as yet undefined mechanism, an ARN-dependent pressor reflex evoked by ipsilateral renal artery stenosis.