IN-VIVO AND IN-VITRO NEUROTOXIC ACTION OF PLASMA ULTRAFILTRATE FROM UREMIC PATIENTS

Background. In order to investigate the aetiology of uraemic neuropath y, we evaluated the neurotoxic activity of plasma from uraemic patient s. To this end we prepared a concentrate (1:1000) of 2-60 kDa MW compo unds from paired filtration dialysis ultrafiltrate and evaluated its a ctivity on peripheral nerve conduction in vivo and in vitro. Methods. The in vivo neurotoxidity was tested on rat sciatic nerve by intraneur al injection of the uraemic concentrate, followed, 1 to 6 days later, by electrophysiological assessment of motor response and maximum condu ction velocity. In vitro experiments were performed on isolated frog s ciatic nerve in the presence of uraemic concentrate, and the neurotoxi city was evaluated from the rate of the decrease in the amplitude of t he evoked maximal action potential. Results. In the in vivo experiment s, the sciatic nerves injected with the uraemic concentrate showed a d ecrease in maximum conduction velocity and a progressive impairment in evoked motor response. In the in vitro experiments uraemic concentrat e induced a dose-dependent neurotoxic effect. Conclusions. Our study d emonstrates the presence in plasma of uraemic patients of a compound o f 2-60 kDa MW with neurotoxic activity.