DETECTION OF OXIDANTS IN UREMIC PLASMA BY ELECTRON-SPIN-RESONANCE SPECTROSCOPY

Depletion of antioxidants and the presence of products of free radical damage in plasma suggest that oxidative stress is increased in uremia . We have developed an application of electron spin resonance spectros copy, and used this method to show that a stable oxidizing component o r components of plasma accumulate in uremia. No oxidizing activity was detectable in plasma from subjects with normal renal function. The ox idant was detected by its capacity to oxidize the spin trap 3,5-dibrom o-4-nitrosobenzene sulphonate (DBNBS). The oxidant was dialyzable from plasma, had an upper molecular weight limit of about 3,000 Daltons an d was stable over many months. Physiological plasma concentrations of vitamin C, a water soluble congener of vitamin E and reduced glutathio ne were unable to inhibit the oxidizing capacity of uremic plasma. Thu s, uremia is associated with accumulation of an endogenous oxidizing a ctivity at much higher concentrations than in subjects with normal ren al function.