The renorenal reflex responses to physiological stimulation of the afferent renal nerves are species-dependent. In dogs, renal mechanoreceptor (MR) stimulation results in a contralateral excitatory renorenal reflex response with a fall in contralateral renal blood flow and urinary sodium excretion at unchanged mean arterial pressure. In cats, renal MR stimulation increases mean arterial pressure and produces variable effects on contralateral renal excretion. In rats, renal MR stimulation results in a contralateral inhibitory renorenal reflex response with contralateral diuresis and natriuresis at unchanged systemic and contralateral renal hemodynamics. Renal chemoreceptor (CR) stimulation produces similar results. In spontaneously hypertensive rats renal MR and CR stimulation fails to produce a renorenal reflex response.