VARIATIONS IN DIETARY-FAT AND CHOLESTEROL INTAKES MODIFY ANTIOXIDANT STATUS OF SHR AND WKY RATS

The effects of varying dietary fat saturation [butter (B), beef tallow (BT)] or polyunsaturation [(n-6) soybean oil (SBO), (n-3) menhaden oi l (MO)] and cholesterol content (0.05 and 0.5 g/100 g) on systolic blo od pressure (SBP), plasma lipids and tissue antioxidant status were in vestigated in 14-wk-old spontaneously hypertensive rats (SHR) and norm otensive Wistar Kyoto (WKY) rats. Varying dietary fat composition for 9 wk had no influence on SEP in either SHR or WKY rats. Rats fed MO di ets exhibited smaller (P < 0.05) body weight gains, lower (P < 0.05) f eed efficiency ratios and lower (P < 0.05) plasma cholesterol concentr ations than those fed the B, BT and SBO diets. Significant (P < 0.05) interactions for animal strain x cholesterol intake and animal strain x fat source were noted for serum cholesterol concentrations. SHR exhi bited higher (P < 0.05) RBC and liver catalase (CAT), and heart and li ver superoxide dismutase (SOD) activities similar to those of WKY rats . The lower (P < 0.01) RBC, heart and liver glutathione peroxidase (GS H-Px) activities observed in SHR coincided with higher (P < 0.01) glut athione reductase (GSSG-Red), compared with WKY rats. Dietary choleste rol intake had no effect on RBC, heart and liver total sulfhydryl conc entration or GSH-Px activities, but increased (P < 0.001) liver GSSG-R ed. Feeding MO resulted in lower (P < 0.001) RBC and heart GSH-Px acti vities. In contrast, feeding B and BT resulted in lower GSH-Px in live r. The significant (P < 0.01) animal strain x fat source interaction o btained for liver GSH-Px activity indicated that SHR responded differe ntly to polyunsaturated fatty acid feeding than their WKY counterparts . Diet-induced changes in tissue antioxidant status were tissue specif ic and did not affect the development of hypertension in SHR.