Birch H L, Wilson A M, Goodship A E
Royal Veterinary College, North Mymms, Hatfield, Herts, UK.
J Exp Biol. 1997 Jun;200(Pt 11):1703-8. doi: 10.1242/jeb.200.11.1703.
Tendons that store energy during locomotion, such as the equine superficial digital flexor tendon (SDFT) and human Achilles tendon, suffer a high incidence of central core degeneration which is thought to precede tendon rupture. Although energy storage contributes to the efficiency of locomotion, tendons are not perfectly elastic and some energy is lost in the form of heat. Recent studies have shown that the central core of equine SDFT reaches temperatures as high as 45 degrees C during high-speed locomotion. In this study, we test the hypothesis that hyperthermia causes tendon cell death and results in tendon central core degeneration. Tendon fibroblasts cultured from the core of the equine SDFT were subjected to a temperature of 45 degrees C in an in vitro system for 0-180 min, and cell survival fraction was measured and compared with that for equine dermal fibroblasts and a commercial rat kidney fibroblast cell line (NRK 49F). Tendon fibroblasts were significantly more resistant to hyperthermia than NRK 49F cells after 30, 45 and 60 min of heating and significantly more resistant than dermal fibroblasts after 45 and 60 min of heating. After 10 min of heating at 45 degrees C, the tendon fibroblast cell survival fraction was 91 +/- 4%, whereas heating for 10 min at 48 degrees C resulted in a drop in the cell survival fraction to 22 +/- 4%. In conclusion, while temperatures experienced in the central core of the SDFT in vivo are unlikely to result in tendon cell death, repeated hyperthermic insults may compromise cell metabolism of matrix components, resulting in tendon central core degeneration.
在运动过程中储存能量的肌腱，如马的浅屈趾肌腱（SDFT）和人的跟腱，中央核心退变的发生率很高，而这种退变被认为是肌腱断裂的先兆。尽管能量储存有助于提高运动效率，但肌腱并非完全弹性，会以热的形式损失一些能量。最近的研究表明，马SDFT的中央核心在高速运动时温度高达45摄氏度。在本研究中，我们检验了高温导致肌腱细胞死亡并导致肌腱中央核心退变的假说。从马SDFT核心培养的肌腱成纤维细胞在体外系统中于45摄氏度下处理0至180分钟，测量细胞存活分数，并与马皮肤成纤维细胞和商业大鼠肾成纤维细胞系（NRK 49F）进行比较。加热30、45和60分钟后，肌腱成纤维细胞对高温的耐受性明显高于NRK 49F细胞，加热45和60分钟后，其耐受性明显高于皮肤成纤维细胞。在45摄氏度下加热10分钟后，肌腱成纤维细胞的存活分数为91±4%，而在48摄氏度下加热10分钟导致细胞存活分数降至22±4%。总之，虽然体内SDFT中央核心所经历的温度不太可能导致肌腱细胞死亡，但反复的热损伤可能会损害基质成分的细胞代谢，导致肌腱中央核心退变。
