In vivo verification of renal denervation

To examine the potential use of the nasopharyngeal reflex to verify renal denervation, 12 conscious rabbits with bilateral renal flow probes were briefly exposed (5-10 sec) to formaldehyde vapor. In each animal one kidney was surgically denervated. Innervated kidneys (norepinephrine content = 117.8±15 pg/mg) exhibited marked decreases in renal blood flow (-80.9±7.7%) in response to formaldehyde. Denervated kidneys had reduced norepinephrine content (3.7±1.7 pg/mg) and small changes in renal blood flow (-11.1±3.0%, p<0.01 vs innervated). In 2 partially innervated kidneys norepinephrine content was reduced (17.6±5.2 pg/mg), yet the formaldehyde-induced reduction in renal blood flow (-81.0±12.3%) was similar to the innervated kidneys. In the innervated kidneys, phentolamine pretreatment attenuated (p<0.05) and combined α-adrenergic and ganglionic blockade abolished (p<0.01) the decrease in vascular conductance. The results suggest that renal norepinephrine content is not a sensitive indicator of functional innervation of the kidney and that the nasopharyngeal reflex is a convenient, in vivo method to determine functional innervation of the kidney. In addition, the data demonstrate that renal vasoconstriction elicited by the nasopharyngeal reflex is mediated primarily by renal nerves, but not entirely by activation of α-adrenergic mechanisms.