Milligan L P, McBride B W
J Nutr. 1985 Oct;115(10):1374-82. doi: 10.1093/jn/115.10.1374.
Results from recent in vitro studies indicate that in excess of 20% of the energy expenditure of skeletal muscle, duodenal epithelium and liver of domestic ruminants is to achieve Na+ and K+ transport across the plasma membrane. The energy cost of active Ca2+ transport is less clear but is likely less than 10% of the total expenditure of skeletal muscle at rest. Energy expenditure on Na+ and K+ transport was quite sensitive to the physiological state of the animal. During lactation, Na+ and K+ transport accounted for nearly half of the in vitro O2 uptake of skeletal muscle, duodenal epithelium and liver. The energetic cost of supporting Na+ and K+ transport was also elevated in young, as compared with older animals, by feed intake and by exposure to cold. Na+ and K+ transport appears to be a substantial component of the maintenance energy expenditure of ruminant tissues. Its variation, therefore, implies that change of maintenance energy expenditures with physiological state of the animal warrants serious attention.
近期体外研究结果表明，家畜反刍动物骨骼肌、十二指肠上皮和肝脏超过20%的能量消耗用于实现钠离子和钾离子跨质膜的运输。主动运输钙离子的能量消耗尚不清楚，但可能低于骨骼肌静息时总能量消耗的10%。钠离子和钾离子运输的能量消耗对动物的生理状态相当敏感。在哺乳期，钠离子和钾离子运输占骨骼肌、十二指肠上皮和肝脏体外氧气摄取量的近一半。与成年动物相比，幼龄动物因采食量和暴露于寒冷环境，维持钠离子和钾离子运输的能量消耗也会增加。钠离子和钾离子运输似乎是反刍动物组织维持能量消耗的重要组成部分。因此，其变化意味着维持能量消耗随动物生理状态的改变值得高度关注。
