Mehl M L, Sarkar D K, Schott H C, Brown J A, Sampson S N, Bayly W M
Department of Veterinary Clinical Sciences, Washington State University, Pullman 99164, USA.
Equine Vet J Suppl. 1999 Jul(30):567-9. doi: 10.1111/j.2042-3306.1999.tb05285.x.
Eight mature mares were exercised for 20 min at 60% VO2max and to fatigue at 95% VO2max. Plasma beta-endorphin (EN) concentrations were determined before exercise, after a 10 min warm-up, and at the end of each exercise test. Mean +/- s.e. beta-endorphin concentrations were significantly (P < 0.05) higher following work at 95% VO2max when compared to that at 60% VO2max (420.0 +/- 102.7 vs. 269.9 +/- 30.69 pg/ml). Pre-exercise samples were collected between 1000 and 1500 h. In order to evaluate whether any cyclic changes in EN secretion effects may have influenced results, a subsequent study was completed using 12 horses to assess diurnal fluctuations in EN concentrations, by measuring EN concentration every 2 h for a 24 h period. There was no statistical difference in mean values at any time between 0800 and 2000 h. Whether individual differences in EN concentrations reflected varying degrees of stress associated with the exercise could not be determined. Any possible link between EN concentration and exercise stress in exercising horses awaits clarification.
8匹成年母马先以60%最大摄氧量运动20分钟，然后以95%最大摄氧量运动至疲劳。在运动前、10分钟热身之后以及每次运动测试结束时测定血浆β-内啡肽（EN）浓度。与以60%最大摄氧量运动相比，以95%最大摄氧量运动后，平均±标准误β-内啡肽浓度显著升高（P<0.05）（420.0±102.7对269.9±30.69 pg/ml）。运动前样本在1000至1500时采集。为了评估EN分泌效应的任何周期性变化是否可能影响结果，随后使用12匹马完成了一项研究，通过在24小时内每2小时测量一次EN浓度来评估EN浓度的昼夜波动。在0800至2000时之间的任何时间，平均值均无统计学差异。无法确定EN浓度的个体差异是否反映了与运动相关的不同程度的应激。运动马匹中EN浓度与运动应激之间的任何可能联系有待阐明。
