P-543: Sympathetic nervous system activation in renal insufficiency is due to signals from the failing kidneys but not to circulating toxins of uremia

Increased activity of the sympathetic nervous system has been observed in renal failure and contributes to hypertension and increased cardiovascular mortality in patients with renal insufficiency. However, it is unclear whether the excitation of the sympathetic system is caused by the failing remnant kidneys or by circulating toxins of uremia. We compared muscle sympathetic nerve activity (MSNA, microneurography), mean arterial blood pressure (MAP, automatic sphygmomanometry), calf blood flow (plethysmography), heart rate (HR, ECG) and calculated calf vascular resistence (CVR) in patients on chronic hemodialysis (HD), in renal transplant recipients with stable graft function (serum creatinine