Effect of hemorrhagic reduction in blood pressure on recovery from acute renal failure

The effect of hemorrhagic reduction in systemic blood pressure (SBP) to 90 mm Hg for four hours on autoregulation of renal blood flow (RBF), renal function, and renal histology was examined in control rats, one week norepinephrine-induced acute renal failure (NE-ARF) rats with intact renal nerves, and one week NE-ARF rats with prior renal denervation. The results showed that in control rats, hemorrhagic SBP reduction to 90 mm Hg had no effect on autoregulation of RBF (autoregulatory index = 0.09 +/- 0.02), creatinine clearance, or renal histology. However, in one week NE-ARF rats with intact renal nerves, hemorrhagic reduction in SBP to 90 mm Hg was associated with marked impairment of autoregulation of RBF (autoregulatory index = 3.49 +/- 0.25), further reduction in creatinine clearance from 0.59 +/- 0.08 ml/min to 0.36 +/- 0.14 ml/min, and histologic evidence of recurrent ischemic injury. Renal denervation prior to SBP reduction improved autoregulation of RBF (autoregulatory index = 0.30 +/- 0.09), prevented the further reduction in creatinine clearance, and significantly ameliorated the deleterious effect on renal histology seen in innervated NE-ARF rats. These results suggest the potential importance of the loss of autoregulation of RBF on the course of NE-ARF, and further support the pathogenetic role of renal nerves in the loss of autoregulation.