AJP - Cell Physiology, Vol 258, Issue 3 C429-C435, Copyright © 1990 by American Physiological Society
Free radical injury to skeletal muscles of young, adult, and old mice
E. Zerba, T. E. Komorowski and J. A. Faulkner
Department of Physiology, University of Michigan, Ann Arbor 48109-0622.
We tested the hypotheses that 1) muscles of old mice are more susceptible
to injury than muscles of young and adult mice, and 2) secondary or delayed
onset injury results from free radical damage. Extensor digitorum longus
muscles were injured in situ by lengthening contractions. Injury was
assessed by measurement of maximum isometric tetanic force (Po) expressed
as a percentage of the control value and by morphological damage. Mice were
treated with a free radical scavenger, polyethylene glycol-superoxide
dismutase (PEG-SOD). Three days postinjury, the Po of 44% for muscles of
nontreated old mice was significantly lower than the Po of 58 and 61% for
those of young and adult mice. In each group, the secondary injury at 3
days was alleviated by treatment with PEG-SOD. For treated muscles of
young, adult, and old mice, values for Po were 88, 80, and 70%,
respectively. We conclude that muscles of old mice are more susceptible to
injury than muscles of young or adult mice and that free radicals
contribute to the secondary or delayed onset injury.
