Neurogenic factors and hypertension in chronic renal failure

The association between hypertension and chronic renal disease is well recognized. Various factors may play a role in the pathogenesis of hypertension in chronic renal failure. Those include sodium retention and volume expansion, and increased activity of vasoconstrictors, such as the renin-angiotensin system. More recently, increased activity of the sympathetic nervous system has emerged as a leading factor in the pathogenesis of hypertension in these patients. We have used the model of 5/6 nephrectomized rats to study the role of the sympathetic nervous system in the pathogenesis of this form of hypertension. We have shown greater norepinephrine turnover rate in the posterior hypothalamic nuclei and locus coeruleus of CRF than control rats. Dorsal rhizotomy prevented the rise in blood pressure and the increase in NE turnover rate in the posterior hypothalamus and the locus coeruleus. An acute injury to the kidney produced by intrarenal injection of phenol, causes an immediate rise in blood pressure and in NE secretion from the posterior hypothalamus, that can be prevented by renal denervation. Dorsal rhizotomy prevented the development of hypertension in rats with chronic renal failure. The studies suggest that afferent impulses from the kidney to central integrative structures in the brain may be responsible for the rise in blood pressure in chronic renal failure.