Participation of the sympathetic nervous system in hypertension in rats with subtotal renal ablation.

To clarify the role of the sympathetic nervous system in the development of hypertension in chronic renal failure, plasma levels and urinary excretions of catecholamines were evaluated in male Sprague-Dawley rats. The renal mass of the rats was reduced by removing one kidney and two-thirds of the contralateral kidney (5/6 nephrectomy). Five-sixths nephrectomy was followed by significant increases in serum creatinine (to 0.55 +/- 0.03 mg/dl) and urea nitrogen (to 42.9 +/- 3.8 mg/dl). There was a concomitant increase in mean blood pressure, measured directly by an implanted aortic catheter, in comparison with control rats (155.3 +/- 8.3 versus 123.6 +/- 3.3 mmHg, P less than 0.01). Both plasma levels and urinary excretion of norepinephrine and epinephrine were elevated in the 5/6-nephrectomized rats compared with controls. Mean blood pressure correlated negatively with 24-h creatinine clearance (r = -0.66, P less than 0.05), and positively with plasma norepinephrine (r = 0.83, P less than 0.01) and urinary excretion of norepinephrine (r = 0.63, P less than 0.05). These results suggest that not only the decrease in renal function, but also hyperactivity of the sympathetic nervous system, may be involved in the pathogenesis of hypertension in rats with subtotal renal ablation.