Fig. 3.

Antioxidant activity. (A) Cytosolic superoxide dismutase (SOD) activity was significantly greater in red muscle (n=8) than in white muscle (n=8; Student's t-test, *P<0.001). (B) Mitochondrial SOD activity was significantly greater in red muscle (n=8) than in white muscle (n=8, Student's t-test, *P<0.001). The insets show activity in per gram of cytoplasm (A) and per gram of mitochondria (B), calculated using TEM ultrastructural data assuming that 70% of tissue mass is intracellular, and that the centrifuged pellet was pure mitochondria. Cytosolic SOD activity in U g⁻¹ cytoplasm was significantly higher in red muscle than in white muscle (*P<0.001), while mitochondrial SOD activity in U g⁻¹ mitochondria was higher in white muscle (*P<0.001). (C) Catalase (CAT) activity in white muscle was below detection limits. CAT activity was significantly greater in red muscle (Student's t-test, *P<0.001). Data are means±s.e.m.