22 A. Walczewska et al. Blood phagocyte chemiluminescence Table 3 presents the luminol-dependent whole blood baseline CL, Peak CL intensity, and Total CL after PMA stimulation of blood phagocyte in rats fed the low-fat and high-fat diets containing different fats. The CL parameters did not differ significantly between rats fed the low-fat diets, although a tendency to increase baseline and PMA-evoked phagocyte oxidative burst in low-FO fed animals was observed. The baseline and PMA-stimulated phagocyte chemiluminescence were significantly lower in high-lard fed animals compared to low-lard (p<0.05), high-SO (p<0.01), and high-FO (p<0.05) fed rats. The Peak and Total CL of high-SO fed rats were 1.33- and 1.25-fold higher, respectively, than of animals fed low-SO (p<0.05), although there was no significant difference in the baseline blood CL between low-SO and high SO fed rats. Among rats fed the high-fat diets, the CL Peak intensity of blood phagocytes after PMA stimulation was significantly lower in high-FO than in high-SO fed animals (p<0.01). Glutathione redox status in erythrocytes There were no significant differences in the erythrocyte GSH and GSSH levels between rats fed low-fat and high-fat diet prepared with the same fats, however there were significant differences in their concentrations between animals fed various fats in the same energy quantity in the diet (Fig. 2). The lowest GSH and the highest GSSH concentrations were observed in RBC of rats fed both low and high SO diets (p<0.001 vs low and high FO; p<0.01 vs low and high lard). Consequently, the GSH/GSSG ratio was the lowest in the erythrocytes of animals fed low and high SO (Fig. 2C). Although the reduced GSH level in the erythrocytes of low-FO fed rats was significantly higher than of low-lard fed animals (p<0.01; Fig. 2A), but the antioxidant status measured as the GSH/GSSG ratio was significantly lower in these rats compared to low- lard fed animals (p<0.01; Fig. 2C). The GSH/GSSG ratio was significantly higher in low and high-lard fed groups compared to animals fed the same energy with SO and FO in the diet (Fig. 2C). Total plasma antioxidant ability The total antioxidant plasma capacity was evaluated by two methods which gave slightly different results. Plasma potency to reduce Fe (III) in the FRAP test did no show any differences between animals fed high-fat and low-fat containing the same fat type. However, plasma of rats fed both low and high SO had the highest antioxidant capacity among groups fed the same energy with lard and FO (p<0.05; Fig. 3A). DPPH radical scavenging activity of plasma was respectively 2.08- and 1.29-times lower in rats fed high-lard and high-FO than in rats fed the corresponding low-fat diet (p<0.001 and p<0.05, respectively; Fig. 3B). In Fig. 2. The effect of the low-fat (LF) and high-fat (HF) diets containing lard, sunflower oil, or fish oil on the concentrations of (A) glutathione (GSH), (B) oxidized glutathione (GSSG), and (C) GSH/GSSG ratio in rat erythrocytes. Values are expressed as mean ± SEM (n = 5–8). Significant differences are as follows: a p<0.01 vs other LF or HF diets; b p<0.01 vs low-lard diet; c p<0.01 vs high-lard diet. J. Clin. Biochem. Nutr.