The pattern of change in skeletal muscle oxidative injury and non‐heme iron during aging differs between fast and slow muscles

Abstract

The aging‐related elevation in skeletal muscle non‐heme iron (NHI) is thought to be a contributing factor to the development of oxidative stress and sarcopenia. However, the iron status of aging slow twitch muscle has not been reported. This study examined the association between NHI and oxidative injury among two muscles that show a divergent pattern of aging‐related muscle atrophy; the fast twitch tibialis anterior (TA) and slow twitch soleus (Sol). Male F344BN rats were studied at 8, 18, 28, and 36 months of age. The animals were anesthetized and muscles were harvested for analysis of NHI and oxidative injury measures. The TA mass was greater than the Sol (p<0.05) and showed atrophy beginning at 28 months compared to 18 month values (p<0.05). The Sol showed atrophy only at 36 months (p<0.05). NHI concentration (nmol/gww) of the Sol was increased at 36 months (95.4±9.3; p<0.05) compared to the other age groups and coincided with the decline in muscle mass. The TA NHI was also increased at 36 months (46.3±8.2; p<0.05); after the onset of muscle atrophy and to a lesser extent than that of the soleus (p<0.05). Lipid peroxidation was unchanged in the TA (p>;0.05) but increased (p<0.05) in the Sol at 36 months compared to 8 and 18 month groups. In summary, elevations in NHI concentration and oxidative injury were better aligned with the Sol pattern of atrophy than the TA in response to aging.Supported by NIH 5R03AG032033 (KCD)