Nitric oxide synthesis inhibition retards surgical reversal of one-kidney Goldblatt hypertension in rats.

Surgical correction of renal artery stenosis in Goldblatt hypertension rapidly normalizes blood pressure and increases renal function. This study was conducted in 1-kidney, 1 clip (1K1C) Goldblatt hypertensive rats to examine whether the unclipping-induced reversal of blood pressure and renal function is mediated by nitric oxide (NO). The 1K1C rats were prepared and given tap water with or without supplementation of NG-nitro-L-arginine methyl ester (L-NAME). Systolic blood pressure (SBP) before and after renal artery clipping was measured with the tail-cuff method. Four weeks later, surgical unclipping was performed while blood pressure and renal function responses were determined. The results show that clipping the renal artery for 4 weeks increased SBP from 140+/-5 to 183+/-6 mm Hg (P<0.05). Concurrent L-NAME treatment accelerated and aggravated the clipping-induced increases in SBP from 138+/-6 to 219+/-8 mm Hg (P<0.05). Surgical unclipping reduced blood pressure to normotensive levels within 2 hours in all hypertensive rats with and without chronic or acute L-NAME treatment. However, the magnitude of reductions in blood pressure in the initial 1 hour after unclipping was significantly less in L-NAME-treated rats than in nontreated rats (9+/-2% versus 16+/-1%, P<0.05). Despite reducing blood pressure, unclipping significantly increased glomerular filtration rate, urine flow, and sodium and potassium excretions, but the extent of the increases in these renal functions was significantly attenuated in L-NAME-treated rats. These data suggest that NO production partly contributes to the hypotensive and renal responses to unclipping but does not mediate the reversal of renovascular hypertension of this model.

Effects of renal artery reconstruction on kidney perfusion and tubular function measured by new radionuclide techniques.

Therapeutic effects of renal artery reconstruction on kidney perfusion and function were studied in 36 patients using new methods for analyzing radionuclide studies. Effective renal plasma flow, glomerular filtration fraction and parameters indicating perfusion and tubular transport improved significantly in patients with postoperative normalization of blood pressure. Patients with a patent renal artery on angiogram but without normalization of blood pressure showed an improvement of parameters such as effective renal plasma flow, glomerular filtration fraction and tubular transport time, whereas the perfusion index remained unchanged. In the group with re-stenosis or re-occlusion all parameters deteriorated after surgery. Discriminant analysis of preoperative data showed that success of surgery could be predicted with high degree of certainty (65% for improvement and 92% for no improvement). The results indicate, that radionuclide methods and arteriography are complementary in the evaluation of the hemodynamic consequences of a renal artery stenosis. They also help to assess the effects of reconstructive surgery and to predict operative success.