补充左旋精氨酸对耐力训练大鼠股外肌抗氧化酶系的影响

目的:研究补充左旋精氨酸(L-Arg)对耐力训练大鼠股外肌抗氧化酶系的影响,了解一氧化氮及其自由基衍生物对耐力训练机体骨骼肌自由基生成和清除的作用。方法:通过适应性训练筛选出40只SD雄性大鼠,按体重随机分为:安静对照组、耐力训练组、小剂量 耐力训练组、大剂量 耐力训练组,每组10只。除安静对照组外其他动物进行了4周水平跑台耐力训练,小剂量 耐力训练大鼠和大剂量 耐力训练大鼠分别在每次训练前一小时左右按照40mg/kg体重的剂量和500mg/kg体重的剂量给予L-Arg水溶液灌胃;4周训练后测定各组大鼠股外肌丙二醛(MDA)含量、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽转移酶(GST)的活性,以及血清肌酸激酶(CK)活性。结果:(1)耐力训练对大鼠安静状态下股外肌CAT活性没有影响;给予小剂量L-Arg能使耐力训练大鼠安静状态下股外肌CAT活性显著降低(P<0.01),给予大剂量L-Arg反而使CAT活性回升;(2)耐力训练对大鼠安静状态下股外肌SOD活性没有影响,补充L-Arg可使大鼠股外肌SOD活性明显升高(小剂量P<0.01,大剂量P<0.05);(3)耐力训练可使大鼠安静状态下股外肌GST活性显著下降(P<0.01),补充L-Arg则使其下降不明显(P>0.05);(4)耐力训练能够使安静大鼠股外肌MDA和血清CK显著减少(P<0.05),补充L-Arg会增加经过耐力训练的大鼠安静状态下股外肌MDA生成(P<0.01),但血清CK浓度则下降,并且下降趋势随补充L-Arg剂量增加而增加。结论:在耐力运动中NO能够促进骨骼肌内超氧化物自由基及其衍生物自由基的生成,较高浓度的NO还能够促进过氧化氢、过氧化物和脂质氢等自由基的生成,对骨骼肌有一定的自由基损伤作用。但其上调血流量的保护作用能够部分抵消其带来的自由基损害作用。

Effect of Supplementation of Exogenous L-Arg on the Antioxidant Enzymes in Vastus Lateralis of Rats undergoing Endurance Training

Objective The present study aimed at investigating the effects of nitric oxide (NO) and its free radical ramifications on the activities of antioxidant enzymes in the skeletal muscle of rats undergoing endurance training.Methods After beforehand training, 40 male SD rats were chosen and randomly divided into 4 groups in according to the training performance and body weights: (1) sedentary group (SG); (2) endurance training group (ETG); (3) endurance training with low dose of L-Arg group (LDTG); and (4) endurance training with high dose of L-Arg group (HDTG). All rats except the SG underwent 4 weeks of endurance training on treadmill. The LDTG was given 40mg/kg wt of L-Arg, and the HDTG group was given 500mg/kg wt of L-Arg 1 hour before training of each day. All rats were killed 24 hours after the final training. The MDA, CAT, SOD and GST activities in vastus lateralis, and serum CK activity were determined. Results (1)The CAT activity in SG remained unchanged,while decreased significantly in LDTG (P<0.01),and showed some trend of increasing in HDTG. (2) SOD activity remained unchanged in ETG, however,increased significantly in LDTG(P<0.05) and HDTG(P<0.01). (3)GST activity decreased significantly in ETG (P<0.01),but showed no change in groups with supplementation of L-Arg. (4) Endurance training reduced MDA production and serum CK level in SG significantly (P<0.05). The production of MDA increased in groups with supplementation of L-Arg. However,serum CK decreased while the dose of L-Arg increased.Conclusions The damaging effect of nitric oxide as a free radical appeared mainly through increasing the production of superoxide radical and its ramification.High level of NO could also increase the output of free radicals such as peroxide, hydro peroxide and lipoxide hydrogen, and hence aggravate the damage of the skeletal muscle. But it's free radical damage effects can be partly mitigated by its upgrade-blood-stream effects.