Direct measurement of sympathetic activity: new insights into disordered blood pressure regulation in chronic renal failure.

The ability to record sympathetic nerve activity in conscious human subjects using intraneural microelectrodes (microneurography) has proven to be a powerful clinical research tool, which has shed new light on the pathophysiology of important blood pressure problems as exemplified in studies of patients with chronic renal failure. Hypertension is present in the majority of hemodialysis patients and is a major risk factor for their excessive mortality from heart attack and stroke. Microneurographic studies indicate that there is a neurogenic component to this hypertension. In addition, severe episodic hypotension is an important complication of maintenance hemodialysis. Microneurographic studies have advanced the concept that abrupt paradoxical withdrawal of sympathetic vasoconstrictor drive is an important cause of this episodic hypotension. These microneurographic data provide the conceptual framework for systematic assessment of new therapeutic strategies.