Miller Benjamin F, Ehrlicher Sarah E, Drake Joshua C, Peelor Frederick F, Biela Laurie M, Pratt-Phillips Shannon, Davis Michael, Hamilton Karyn L
Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado;
Department of Animal Science, North Carolina State University, Raleigh, North Carolina; and.
J Appl Physiol (1985). 2015 Apr 1;118(7):811-7. doi: 10.1152/japplphysiol.00982.2014. Epub 2015 Jan 22.
Canis lupus familiaris, the domesticated dog, is capable of extreme endurance performance. The ability to perform sustained aerobic exercise is dependent on a well-developed mitochondrial reticulum. In this study we examined the cumulative muscle protein and DNA synthesis in groups of athletic dogs at the onset of an exercise training program and following a strenuous exercise training program. We hypothesized that both at the onset and during an exercise training program there would be greater mitochondrial protein synthesis rates compared with sedentary control with no difference in mixed or cytoplasmic protein synthesis rates. Protein synthetic rates of three protein fractions and DNA synthesis were determined over 1 wk using (2)H2O in competitive Alaskan Huskies and Labrador Retrievers trained for explosive device detection. Both groups of dogs had very high rates of skeletal muscle protein synthesis in the sedentary state [Alaskan Huskies: Mixed = 2.28 ± 0.12, cytoplasmic (Cyto) = 2.91 ± 0.10, and mitochondrial (Mito) = 2.62 ± 0.07; Labrador Retrievers: Mixed = 3.88 ± 0.37, Cyto = 3.85 ± 0.06, and Mito = 2.92 ± 0.20%/day]. Mitochondrial (Mito) protein synthesis rates did not increase at the onset of an exercise training program. Exercise-trained dogs maintained Mito protein synthesis during exercise training when mixed (Mixed) and cytosolic (Cyto) fractions decreased, and this coincided with a decrease in p-RpS6 but also a decrease in p-ACC signaling. Contrary to our hypothesis, canines did not have large increases in mitochondrial protein synthesis at the onset or during an exercise training program. However, dogs have a high rate of protein synthesis compared with humans that perhaps does not necessitate an extra increase in protein synthesis at the onset of aerobic exercise training.
家犬（Canis lupus familiaris）能够展现出极强的耐力表现。持续进行有氧运动的能力依赖于发育良好的线粒体网。在本研究中，我们检测了运动犬在运动训练计划开始时以及经过高强度运动训练计划后的累积肌肉蛋白质和DNA合成情况。我们假设，在运动训练计划开始时以及训练期间，与久坐不动的对照组相比，线粒体蛋白质合成速率会更高，而混合蛋白或细胞质蛋白合成速率则无差异。在为期1周的时间里，使用重水（²H₂O）测定了经过爆炸物检测训练的阿拉斯加哈士奇犬和拉布拉多寻回犬三种蛋白质组分的蛋白质合成速率以及DNA合成情况。两组犬在久坐状态下骨骼肌蛋白质合成速率都非常高（阿拉斯加哈士奇犬：混合蛋白 = 2.28 ± 0.12，细胞质蛋白 = 2.91 ± 0.10，线粒体蛋白 = 2.62 ± 0.07；拉布拉多寻回犬：混合蛋白 = 3.88 ± 0.37，细胞质蛋白 = 3.85 ± 0.06，线粒体蛋白 = 2.92 ± 0.20%/天）。在运动训练计划开始时，线粒体蛋白质合成速率并未增加。经过运动训练的犬在运动训练期间，当混合蛋白和细胞质蛋白组分减少时，仍能维持线粒体蛋白合成，这与核糖体蛋白S6磷酸化水平（p - RpS6）降低以及乙酰辅酶A羧化酶磷酸化水平（p - ACC）信号转导减少相一致。与我们的假设相反，犬在运动训练计划开始时或训练期间线粒体蛋白合成并未大幅增加。然而，与人类相比，犬的蛋白质合成速率较高，这可能使得在有氧运动训练开始时无需额外增加蛋白质合成。
