Effects of dietary calcium restriction and acute exercise on the antioxidant enzyme system and oxidative stress in rat diaphragm.
Calcium deficiency is considered to increase intracellular calcium level; thus the aim of the current study was to elucidate whether dietary calcium restriction enhanced exercise-induced oxidative stress in rat diaphragm. Twenty male Wistar rats were randomly assigned to either a control group or a group subjected to 1 mo of calcium restriction. In addition, each group was subsequently subdivided into rested or acutely exercised group. Dietary calcium restriction significantly (P < 0.05) upregulated the activities of manganese-superoxide dismutase (Mn-SOD), copper-zinc-superoxide dismutase (Cu-Zn-SOD), and glutathione peroxidase (Gpx) but not catalase. Acute exercise, in addition to calcium restriction, decreased both SOD isoenzymes in the diaphragm of calcium-restricted rats (P < 0.05). On the other hand, calcium restriction resulted in increased Gpx mRNA expression (P < 0.05). In control rats, acute exercise significantly (P < 0.05) increased the expressions of both SOD mRNAs, whereas in the calcium-restricted rats, it increased that of Mn-SOD mRNA (P < 0.05) but decreased that of Gpx mRNA (P < 0.05). Furthermore, reactive carbonyl derivative, a marker of protein oxidation, was significantly greater in the calcium-restricted rats than in the control rats after acute exercise (P < 0.05). The results suggest that antioxidant enzymes in rat diaphragm were upregulated in response to an increased oxidative stress by dietary calcium restriction but that upregulation is not enough to cope with exercise-induced further increase of oxidative stress.
Itoh
Masayuki
M
Fifth Dept. of Internal Medicine, Tokyo Medical Univ., 3-20-1, Chuou, Ami, Inashiki, Ibaraki 300-0395, Japan.
Oh-Ishi
Shuji
S
Hatao
Hidekazu
H
Leeuwenburgh
Christiaan
C
Selman
Colin
C
Ohno
Hideki
H
Kizaki
Takako
T
Nakamura
Hiroyuki
H
Matsuoka
Takeshi
T
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000187:drug effects; D002118:Calcium / Q000172:deficiency*; D002136:Calcium, Dietary; D002374:Catalase / Q000378:metabolism; D017931:DNA Primers; D003964:Diaphragm / Q000201:enzymology / Q000502:physiology*; D004032:Diet; D005979:Glutathione Peroxidase / Q000378:metabolism; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D009929:Organ Size / Q000502:physiology; D018384:Oxidative Stress / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D002136:Calcium, Dietary; D017931:DNA Primers; D009124:Muscle Proteins; D012333:RNA, Messenger; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D002118:Calcium