Norepinephrine and renin activity in chronic renal failure: Evidence for interacting roles in hemodialysis hypertension

To assess the interaction between adrenergic activity and blood pressure regulation in patients with chronic renal failure, plasma norepinephrine (NE) and plasma renin activity (PRA) were measured before and after rigorous ultrafiltration. The significance of PRA was further assessed by anglotensin blockade with saralasin. Two patterns of response were defined: nine patients had low levels of PRA before and after hemodialysis. These patients showed a net fall in norepinephrine and no angiotensin dependence at any time. Failure to stimulate either PRA or norepinephrine was also observed during periods of marked hypotension. Seven other patients had higher PRA, which rose during bemodialysis. This was associated with an increase in NE and postdialysis angiotensin dependence. Patients experiencing hypotension in this group showed a sharp rise in NE, suggesting baroceptor-mediated adrenergic stimulation. In all patients sustaining hypotension during therapy, postdialysis PRA was closely correlated with NE. These results Indicate that hemodialysis mobilizes the renin-angiotensln system to maintain hypertension in a greater proportion of dialysis patients than previously supposed and that impaired renin release following hypotension may represent uremic autonomic dysfunction.