Nordsborg Nikolai, Ovesen Jakob, Thomassen Martin, Zangenberg Mathias, Jøns Christian, Iaia F Marcello, Nielsen Jens Jung, Bangsbo Jens
University of Copenhagen, Department of Exercise and Sport Sciences, Section for Human Physiology, Universitetsparken 13, 2100 Copenhagen, Denmark.
J Physiol. 2008 Mar 1;586(5):1447-59. doi: 10.1113/jphysiol.2007.143073. Epub 2008 Jan 3.
The effect of dexamethasone on Na(+),K(+) pump subunit expression and muscle exchange of K(+) during exercise in humans was investigated. Nine healthy male subjects completed a randomized double blind placebo controlled protocol, with ingestion of dexamethasone (Dex: 2 x 2 mg per day) or placebo (Pla) for 5 days. Na(+),K(+) pump catalytic alpha1 and alpha2 subunit expression was approximately 17% higher (P < 0.05) and the structural beta1 and beta2 subunit expression was approximately 6-8% higher (P < 0.05) after Dex compared with Pla. During one-legged knee-extension for 10 min at low intensity (LI; 18.6 +/- 1.0 W), two moderate intensity (51.7 +/- 2.4 W) exercise bouts (MI(1): 5 min; 2 min recovery; MI(2): exhaustive) and two high-intensity (71.7 +/- 2.5 W) exercise bouts (HI(1): 1 min 40 s; 2 min recovery; HI(2): exhaustive), femoral venous K(+) was lower (P < 0.05) in Dex compared with Pla. Thigh K(+) release was lower (P < 0.05) in Dex compared with Pla in LI and MI, but not in HI. Time to exhaustion in MI(2) tended to improve (393 +/- 50 s versus 294 +/- 41 s; P = 0.07) in Dex compared with Pla, whereas no difference was detected in HI(2) (106 +/- 10 s versus 108 +/- 9 s). The results indicate that an increased Na(+),K(+) pump expression per se is of importance for thigh K(+) reuptake at the onset of low and moderate intensity exercise, but less important during high intensity exercise.
研究了地塞米松对人体运动期间钠钾泵亚基表达及钾肌肉交换的影响。九名健康男性受试者完成了一项随机双盲安慰剂对照试验，服用地塞米松（地塞米松：每日2×2毫克）或安慰剂5天。与安慰剂相比，地塞米松治疗后钠钾泵催化α1和α2亚基表达约高17%（P<0.05），结构β1和β2亚基表达约高6-8%（P<0.05）。在低强度（LI；18.6±1.0瓦）单腿膝关节伸展10分钟、两次中等强度（51.7±2.4瓦）运动 bout（MI(1)：5分钟；2分钟恢复；MI(2)：力竭）和两次高强度（71.7±2.5瓦）运动bout（HI(1)：1分40秒；2分钟恢复；HI(2)：力竭）过程中，与安慰剂相比，地塞米松组股静脉钾含量较低（P<0.05）。在低强度和中等强度运动中，与安慰剂相比，地塞米松组大腿钾释放较低（P<0.05），但在高强度运动中并非如此。与安慰剂相比，地塞米松组在MI(2)中的力竭时间有改善趋势（393±50秒对294±41秒；P=0.07），而在HI(2)中未检测到差异（106±10秒对108±9秒）。结果表明，钠钾泵表达增加本身对于低强度和中等强度运动开始时大腿钾再摄取很重要，但在高强度运动中不太重要。
