Autoxidation and effects of pro- and antioxidants in lyophilized red blood cell membranes.

Oxygen uptake and effects of pro- and antioxidants have been compared at 80 C in lyophilized red blood cell (RBC) bilayer membranes (ghosts). In this dry and relatively immobile system, catalytic metals have pronounced effects. When ghosts are prepared in the usual manner, in phosphate buffer, hypotonic saline, or deionized water (DI), oxygen uptake is extremely slow and limited unless: (a) catalytic metal, e.g. cobaltous ion, is supplied in the absence of metal-complexing buffers and (b) residual phosphate buffer is removed by repeated deionized water or hypotonic saline washes. Ghosts adsorb d-alpha-tocopherol strongly from 1% alcohol emulsion in buffer in amounts far above normal RBC concentrations, whereas synthetic antioxidant uptake seldom exceeds the normal tocopherol level. Uptake and effectiveness of antioxidants introduced by either perfusion or in the vapor phase, and resistance of ghosts to autoxidation introduced by either perfusion or in the vapor phase, and resistance of ghosts to autoxidation are discussed as they relate to protection of lyophilized membranes and freeze-dried foods.