FACTORS AFFECTING THE THIOBARBITURIC ACID TEST AS INDEX OF RED-BLOOD-CELL SUSCEPTIBILITY TO LIPID-PEROXIDATION - A MULTIVARIATE-ANALYSIS

The relationship between formation of thiobarbituric acid reactive sub stances (TBARS) in red blood cells (RBC) after exposure to H2O2 and fa ctors potentially able to modulate it was investigated by a multivaria te analysis in 92 healthy volunteers. The independent covariates consi dered were: RBC membrane fatty acids and cholesterol, RBC antioxidant enzymes and zinc, plasma vitamins A and E and serum selenium, zinc and copper. The stepwise multiple-linear-regression analysis revealed RBC membrane fatty acids and cholesterol as predictors of a consistent pr oportion of the RBC-TBARS variability whereas none of the antioxidants entered the equation. The unsaturation index was the most important i ndividual predictor; RBC-TBARS increased with increasing concentration s of total omega-3 polyunsaturated fatty acids, C 20:5 omega-3 and cho lesterol, whereas they decreased with increasing concentrations of tot al monounsaturated fatty acids, saturated fatty acids, C 16:0 and C 18 :0. It is suggested that formation of TBARS, at least in currently use d conditions, reflects mainly the lipid composition of the tissue unde r investigation, without giving sufficient information about the statu s of the antioxidant defences.