Diet restriction and age alters skeletal muscle capillarity in B6C3F1 mice

The effects of 40% diet restriction on skeletal muscle fiber area, capillary density (CD) and capillary to fiber ratio (C/F) were compared in 12, 24 and 30-month-old female B6C3F1 female hybrid mice. We hypothesized that diet restriction (DR) would retard the aging effects observed in skeletal muscle, in particular DR would pose opposite effects on skeletal muscle capillarity and fiber area. Samples were prepared for light microscopic examination by standard methods and for morphometric analysis using NIH-image software. There was a significant effect of age on muscle fiber area (p<0.05). The age-associated decrease in fiber area between 12 and 30 months of age was greater (p<0.05) in the ad libitum (AL) (37.7%) animals as compared to the diet restricted (DR) mice (29.2%). Diet had a significant effect on CD (p<0.05) and C/F (p<0.05). This finding suggests that the lower capillarity in the older DR mice may have been due to their larger muscle fibers. The results of this study support the contention that diet restriction delays the progression of age-associated muscle atrophy.