Khassaf M, McArdle A, Esanu C, Vasilaki A, McArdle F, Griffiths R D, Brodie D A, Jackson M J
Department of Medicine, University of Liverpool, Liverpool L69 3GA, UK.
J Physiol. 2003 Jun 1;549(Pt 2):645-52. doi: 10.1113/jphysiol.2003.040303. Epub 2003 Apr 11.
Oxidative stress induces adaptations in the expression of protective enzymes and heat shock proteins (HSPs) in a variety of tissues. We have examined the possibility that supplementation of subjects with the nutritional antioxidant, vitamin C, influences the ability of lymphocytes to express protective enzymes and HSPs following exposure to an exogenous oxidant and the response of skeletal muscle to the physiological oxidative stress that occurs during exercise in vivo. Our hypothesis was that an elevation of tissue vitamin C content would reduce oxidant-induced expression of protective enzymes and HSP content. Lymphocytes from non-supplemented subjects responded to hydrogen peroxide with increased activity of superoxide dismutase (SOD) and catalase, and HSP60 and HSP70 content over 48 h. Vitamin C supplementation at a dose of 500 mg day-1 for 8 weeks was found to increase the serum vitamin C concentration by ~50 %. Lymphocytes from vitamin C-supplemented subjects had increased baseline SOD and catalase activities and an elevated HSP60 content. The SOD and catalase activities and the HSP60 and HSP70 content of lymphocytes from supplemented subjects did not increase significantly in response to hydrogen peroxide. In non-supplemented subjects, a single period of cycle ergometry was found to significantly increase the HSP70 content of the vastus lateralis. Following vitamin C supplementation, the HSP70 content of the muscle was increased at baseline with no further increase following exercise. We conclude that, in vitamin C-supplemented subjects, adaptive responses to oxidants are attenuated, but that this may reflect an increased baseline expression of potential protective systems against oxidative stress (SOD, catalase and HSPs).
氧化应激可诱导多种组织中保护性酶和热休克蛋白（HSPs）表达的适应性变化。我们研究了给受试者补充营养抗氧化剂维生素C是否会影响淋巴细胞在暴露于外源性氧化剂后表达保护性酶和HSPs的能力，以及骨骼肌对体内运动过程中发生的生理氧化应激的反应。我们的假设是组织维生素C含量的升高会降低氧化剂诱导的保护性酶表达和HSP含量。未补充维生素C的受试者的淋巴细胞在48小时内对过氧化氢的反应是超氧化物歧化酶（SOD）和过氧化氢酶活性增加，以及HSP60和HSP70含量增加。发现以500毫克/天的剂量补充维生素C 8周可使血清维生素C浓度增加约50%。补充维生素C的受试者的淋巴细胞具有更高的基线SOD和过氧化氢酶活性以及更高的HSP60含量。补充维生素C的受试者的淋巴细胞的SOD和过氧化氢酶活性以及HSP60和HSP70含量在接触过氧化氢后没有显著增加。在未补充维生素C的受试者中，发现单次进行周期测力计运动可显著增加股外侧肌的HSP70含量。补充维生素C后，肌肉的HSP70含量在基线时增加，运动后没有进一步增加。我们得出结论，在补充维生素C的受试者中，对氧化剂的适应性反应减弱，但这可能反映了针对氧化应激的潜在保护系统（SOD、过氧化氢酶和HSPs）的基线表达增加。
