Sympathetic activity response to changes in the intake of sodium in chronic renal failure.

Sympathetic response to differences in sodium intake in patients with chronic renal failure was investigated. All patients were on haemodialysis, first for 3 weeks with conventional dialysate containing 148 mEq/l of sodium, then for another 3 weeks with the conventional dialysate containing 131 mEq/l of sodium. Increase in noradrenaline (NA), adrenaline (A), dopamine (DA) concentrations and dopamine-beta-hydroxylase (DBH) activity were found during the high-sodium haemodialysis. However, DBH activity in patients was significantly lower than in healthy individuals. A significant correlation was found between the level of plasma NA and systolic blood pressure. The present results suggest that a higher intake of sodium causes dysfunction of the sympathetic system.