Hypertension in end-stage renal failure: role of sympathetic nervous system, sodium balance and renal pressor system.

120 subjects, including 16 normal volunteers, 23 essential hypertensive and 81 uraemic patients (34 before the start of haemodialysis and 47 during maintenance haemodialysis) were studied in order to evaluate the interrelationship between mean arterial pressure (MAP) and total exchangeable sodium (NaE), plasma renin activity (PRA) and plasma catecholamines (PC). Significant positive correlations were noted between MAP and PRA and between MAP and PC in the total group of uraemic patients. In patients under conservative treatment MAP correlated significantly with NaE and PRA. Multiple regression analysis demonstrated that the combined effect of NaE and PRA accounted for 50 per cent of the levels of MAP. In patients undergoing chronic haemodialysis MAP lost any correlation with NaE. In these patients the presence of hypertension seemed to be related to the values of PRA and PC. PC increased after two hours of walking and hypertensive patients had higher increments than normotensive patients. These data might support an important role for the adrenergic system in the maintenance of hypertension in dialysis patients.