Postsynaptic adrenergic unresponsiveness in hypotensive haemodialysis patients.

In order to ascertain the significance of autonomic dysfunction in hypotensive maintenance haemodialysis patients, plasma norepinephrine (NE) was measured by radioenzymatic assay in 15 nondiabetic uraemic subjects of similar age and time on dialysis, five of them chronically hypotensive and 10 normotensive. Hypotensive patients had: 1) Significantly higher NE levels than their normotensive counterparts, both in basal conditions and after orthostatism and 2) significantly lesser increments in mean arterial blood pressure during a NE infusion than the normotensive group. Rather than implicating a mechanism based on autonomic neuropathy, our results suggest that in haemodialysis patients with chronic hypotension, there is a defect located at the adrenergic postsynaptic level.