Weijs P J, Schreurs V V, Koopmanschap R E, Grooten H N, Schoonman A T, Boekholt H A
Department of Human and Animal Physiology, Wageningen Agricultural University, The Netherlands.
Br J Nutr. 1993 Jul;70(1):117-25. doi: 10.1079/bjn19930109.
Effects of acute (meal) and chronic (diet) level of protein supply on metabolic leucine utilization were investigated in growing (10 weeks) and mature (> 1 year) rats. Rats were conditioned on a high-protein (HP) diet (210 g casein/kg feed) or a low-protein (LP) diet (75 g casein/kg feed) from 7 weeks of age. Overnight-fasted rats were offered a HP or LP meal during a 8 h 14CO2 breath test with a constant infusion of either L-[1-14C]leucine (carboxyl, CL) or L-[U-14C]leucine (universal, UL). Before the meal 14CO2 output was lower for overnight-fasted rats fed on LP than on HP (P < 0.001), and also lower for growing than for mature rats (P < 0.001). Meal ingestion resulted in a rapid increase in 14CO2 output. From 2 h after the start of the meal the effect of acute protein supply on 14CO2 output was significant (P < 0.001), while the effect of chronic protein supply disappeared for CL. After the meal 14CO2 output was transiently lower for growing than for mature rats (P < 0.05), especially after the LP meal. The difference in 14CO2 output between CL and UL increased transiently after the meal, indicating an increase in decarboxylation relative to total oxidation of leucine.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了急性（进食）和慢性（饮食）蛋白质供应水平对生长（10周龄）和成熟（大于1岁）大鼠代谢性亮氨酸利用的影响。从7周龄起，将大鼠分别用高蛋白（HP）饮食（210 g酪蛋白/kg饲料）或低蛋白（LP）饮食（75 g酪蛋白/kg饲料）进行饲养。在8小时的14CO2呼吸试验期间，给过夜禁食的大鼠提供HP或LP餐，并持续输注L-[1-14C]亮氨酸（羧基，CL）或L-[U-14C]亮氨酸（通用，UL）。进食前，LP饮食喂养的过夜禁食大鼠的14CO2排出量低于HP饮食喂养的大鼠（P < 0.001），并且生长大鼠的14CO2排出量也低于成熟大鼠（P < 0.001）。进食导致14CO2排出量迅速增加。进食开始后2小时起，急性蛋白质供应对14CO2排出量的影响显著（P < 0.001），而CL的慢性蛋白质供应影响消失。进食后，生长大鼠的14CO2排出量暂时低于成熟大鼠（P < 0.05），尤其是LP餐后。进食后，CL和UL之间的14CO2排出量差异短暂增加，表明相对于亮氨酸的总氧化，脱羧作用增加。（摘要截选至250字）
