Itoh Masayuki, Oh-Ishi Shuji, Hatao Hidekazu, Leeuwenburgh Christiaan, Selman Colin, Ohno Hideki, Kizaki Takako, Nakamura Hiroyuki, Matsuoka Takeshi
Fifth Dept. of Internal Medicine, Tokyo Medical Univ., 3-20-1, Chuou, Ami, Inashiki, Ibaraki 300-0395, Japan.
Am J Physiol Regul Integr Comp Physiol. 2004 Jul;287(1):R33-8. doi: 10.1152/ajpregu.00598.2003. Epub 2004 Feb 5.
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.
钙缺乏被认为会增加细胞内钙水平；因此，本研究的目的是阐明饮食钙限制是否会增强大鼠膈肌运动诱导的氧化应激。20只雄性Wistar大鼠被随机分为对照组或接受1个月钙限制的组。此外，每组随后又被细分为静息组或急性运动组。饮食钙限制显著（P < 0.05）上调了锰超氧化物歧化酶（Mn-SOD）、铜锌超氧化物歧化酶（Cu-Zn-SOD）和谷胱甘肽过氧化物酶（Gpx）的活性，但对过氧化氢酶没有影响。除了钙限制外，急性运动还降低了钙限制大鼠膈肌中两种超氧化物歧化酶同工酶的活性（P < 0.05）。另一方面，钙限制导致Gpx mRNA表达增加（P < 0.05）。在对照大鼠中，急性运动显著（P < 0.05）增加了两种超氧化物歧化酶mRNA的表达，而在钙限制大鼠中，它增加了Mn-SOD mRNA的表达（P < 0.05），但降低了Gpx mRNA的表达（P < 0.05）。此外，急性运动后，蛋白质氧化标志物活性羰基衍生物在钙限制大鼠中显著高于对照大鼠（P < 0.05）。结果表明，大鼠膈肌中的抗氧化酶因饮食钙限制导致的氧化应激增加而上调，但这种上调不足以应对运动诱导的氧化应激进一步增加。
