Alterations of superoxide dismutase iso-enzyme activity, content, and mRNA expression with aging in rat skeletal muscle.
The alterations of superoxide dismutase iso-enzyme (Cu,Zn-SOD and Mn-SOD) activities, contents, and mRNA expressions with aging were studied in rat soleus muscle (SO) and extensor digitorum longus muscle (EDL). The activity and content of Cu,Zn-SOD in both muscles were significantly higher in old rats (24 months old) than in young rats (4 months old), whereas those of Mn-SOD showed no difference between young and old rats. After normalization to citrate synthase (CS) activity, however Mn-SOD/CS ratio in SO also showed the age-related increase. Moreover, the activities of other major antioxidant enzymes, glutathione peroxidase (GPX) and catalase (CAT), indicated age-related increases only in SO. As for the expressions of mRNAs for SOD iso-enzymes, that of Cu,Zn-SOD in either muscle showed no significant change with aging, unlike its activity and content, although that of Mn-SOD was decreased with aging only in EDL. Thus, aging appeared to raise the level of antioxidant enzyme system in rat skeletal muscle. However, the resistance of Cu,Zn-SOD and Mn-SOD to oxidative stress accompanied by aging was different, the former being obviously greater than the latter. Such changes also differed in muscle fiber type suggesting that fast-twitch fibers are more susceptible to age-related oxidative stress than slow-twitch fibers.
Oh-Ishi
S
S
Department of Hygiene, National Defense Medical College, Tokorozawa, Japan.
Kizaki
T
T
Yamashita
H
H
Nagata
N
N
Suzuki
K
K
Taniguchi
N
N
Ohno
H
H
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005979:Glutathione Peroxidase / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011916:Rats, Inbred F344; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
D000975:Antioxidants; D007527:Isoenzymes; D012333:RNA, Messenger; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase