低劑量 L-NAME 對耐力訓練大鼠 NOS 表現及耐力性運動表現的影響

Abstract

目的：探討低劑量 L-NAME 及耐力運動訓練對 NOS 表現和耐力性運動表現的影響。方法： Wistar 品系 5 週齡實驗大鼠44隻分兩批，且分為Control組、L-NAME 組、Exercise組及L-NAME + Exercise組。第一批大鼠（每組n=5）實驗處理 4 週後犧牲，分析比目魚肌 nNOS 與 eNOS蛋白及 mRNA 表現。第二批大鼠（每組n=6）實驗處理八週後犧牲，檢比目魚肌肝醣含量及檸檬酸合成酶活性。實驗期間每週定期測量其尾壓，並於第五週及第八週進行耐力性運動訓練測試。實驗數據皆以平均數 ± 標準誤表示，以單因子獨立樣本變異數分析檢定，並以 Tukey 做事後比較，統計水準為 p＜ .05。結果： nNOS 蛋白表現， L-NAME+Exercise 組（473.3 ± 123.2％）顯著高於 Control 組（100.0 ± 0.0％）。eNOS 蛋白表現， L-NAME+Exercise 組（372.0 ± 84.2％）及Exercise 組（344.5 ± 59.1％）顯著高於 Control 組（100.0 ± 0.0％）。eNOS mRNA 表現，L-NAME 組（22.4 ± 3.8％）及 Exercise 組（23.6 ± 3.5％）顯著高於 Control 組（7.7 ± 1.1％），而 L-NAME+Exercise 組（49.3 ± 3.1％）則顯著高於其他三組。比目魚肌肝醣含量，Exercise 組（2.58 ± 0.5 mg/g）及 L-NAME+Exercise 組（2.77 ± 0.3 mg/g）皆顯著高於Control 組（0.8 ± 0.1 mg/g）。檸檬酸合成酶活性中，Exercise 組（47.6 ± 4.8 μmole/mg/min，n=5）及 L-NAME+Exercise 組（41.9 ± 5.6 μmole/mg/min，n=5）皆顯著高於Control 組（20.3 ± 3.8 μmole/mg/min，n=5）及 L-NAME 組（37.3 ± 5.0 μmole/mg/min，n=5）五週耐力性運動表現， Exercise 組（101.7 ± 12分鐘）及L-NAME+Exercise 組（78.0 ± 16.5分鐘）顯著高於Control 組（29.8 ± 10.6分鐘）及 L-NAME 組（29.5 ± 6.9 分鐘）。八週耐力性運動表現，Exercise 組（98.3 ± 6.8分鐘）及L-NAME+Exercise 組（88.0 ± 4.8分鐘）顯著高於Control 組（11.5 ± 3.4分鐘）及 L-NAME 組（13.7 ± 3.5分鐘）。結論：低劑量 L-NAME 配合耐力性運動訓練，能明顯增強 eNOS 及 nNOS 蛋白表現。此現象雖然可能增加骨骼肌中 NO 產量，但卻無法顯著增加骨骼肌肝醣的儲存量及檸檬酸合成酶活性，且因 NO 對有氧代謝系統的抑制作用，反而不利於耐力性運動表現。

Purpose: To investigate the effect of low dosage L-NAME and endurance exercise training on NOS expression and endurance exercise performance. Methods: Forty-four male Wistar rats (five weeks old) were randomly divided into two divisions, and then further divided into four groups: Control, L-NAME, Exercise and L-NAME+Exercise. First division rats (each group n=5) were treated for 4 weeks and sacrificed to analyze the protein expression and mRNA expression for nNOS and eNOS of the soleus. Second division rat (each group n=6) were treated for 8 week and sacrificed to analyze the glycogen content and citrate synthase activity of the soleus. All numerical data were expressed in mean ± SEM. Independent one way ANOVA was used to evaluate the mean difference. The significance level was set at p＜ .05。Results: The nNOS protein expression of L-NAME+Exercise group (473.3 ± 123.2％）was significantly higher than Control group（100.0 ± 0.0％）。The eNOS protein expression of L-NAME+Exercise group (372.0 ± 84.2％) and Exercise group (344.5 ± 59.1％） were significantly higher than Control group（100.0 ± 0.0％）. The eNOS mRNA expression of L-NAME group (22.4 ± 3.8％) and Exercise group (23.6 ± 3.5％) were significantly higher than Control group(7.7 ± 1.1％); and L-NAME+Exercise group (49.3 ± 3.1％) was significantly higher than all other groups. Soleus muscle glycogen content of Exercise group （2.58 ± 0.5 mg/g）and L-NAME+Exercise group (2.77 ± 0.3 mg/g) were significantly higher than Control group (0.8 ± 0.1 mg/g). Citrate synthase activity of Exercise group (47.6 ± 4.8 μmole/mg/min) and L-NAME+Exercise group (41.9 ± 5.6 μmole/mg/min) were significantly higher than Control group (20.3 ± 3.8 μmole/mg/min) and L-NAME group (37.3 ± 5.0 μmole/mg/min). Fifth week endurance exercise performance of Exercise group (101.7 ± 12 min) and L-NAME+Exercise group (78.0 ± 16.5 min) were significantly higher than Control group (29.8 ± 10.6 min) and L-NAME group (29.5 ± 6.9 min). Eighth week endurance exercise performance of Exercise group (98.3 ± 6.8 min) and L-NAME+Exercise group (88.0 ± 4.8 min) were significantly higher than Control group (11.5 ± 3.4 min) and L-NAME group (13.7 ± 3.5 min). Conclusions: The rats treated with low dosage L-NAME and endurance performance will significantly increased eNOS and nNOS protein expression. Although NO production of skeletal muscle increased, but could not increasing glycogen storage and citrate synthase activity of skeletal muscle. Also, NO will inhibits oxidation system to decrease endurance exercise performance.