Ageing is associated in females with a decline in the content and activity of the b-c(1) complex in skeletal muscle mitochondria

The activity of cytochrome-c oxidase [E.C. 1.9.3.1] and b-c(1) complex [E.C. 1.10.2.2.] and the content of cytochromes 6, c + c(1) and a + a(3) in human skeletal muscle mitochondria from orthopaedic patients (108 women and 68 males), of age ranging between 10 and 90 years, have been analyzed. The activity of cytochrome c-oxidase declines with age both in females and males, The activity of b-c(1) complex, which in young females is significantly higher than in young malts, declines sharply in females, but not in males, with ageing. These results reveal that the content of active b-c(1) complex in muscle mitochondria is specifically controlled by female sex hormones.