Utilization for protein synthesis of 2-ketoisocaproate relative to utilization of leucine, as estimated from exhalation of labelled CO2.
Utilization for protein synthesis of 2-ketoisocaproate relative to utilization of leucine, as estimated from exhalation of labelled CO2.
复制标题
2-酮异己酸的蛋白质合成利用率相对于亮氨酸的利用率，根据呼出的标记 CO2 估计。
DOI：
10.1042/cs0750301
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Walser,M
中科院分区：
文献类型：
--
作者：
Imura,K;Shiota,T;Swain,LM;Walser,M
1. 我们之前已经表明，2-酮异己酸（KIC）标记掺入全身蛋白亮氨酸与亮氨酸本身标记同时掺入蛋白质的比率（RWBP）是衡量 KIC 作为亮氨酸替代品营养效率的指标。 2. 为了确定是否可以通过测量标记的 CO2 排泄来间接估计 RWBP，给大鼠口服或静脉注射 [4, 5-3H] 亮氨酸和 [1-14C] 亮氨酸或 [1-14C] KIC。收集呼出的 CO2 6 小时。 3、结果表明，口服后9-14%的KIC发生首过氧化。当静脉内给予同位素时，20分钟后从KIC中排出14CO2的平均速率仍然是从亮氨酸中排出14CO2的平均速率的1.8倍。 4. 口服或静脉注射同位素以及小剂量或大剂量载体的大鼠的全身蛋白质测量的平均 RWBP 与根据平均累积 CO2 排泄估计的平均 RWBP 相同。 5. 我们得出结论：(1) KIC 相对于亮氨酸的营养效率可以通过测量标记的 CO2 排泄来估计，(2) KIC 作为亮氨酸替代品在大鼠中的相对低效可归因于 9-14% 的首过氧化（口服给药时）和比亮氨酸高 80% 的全身氧化敏感性。
1. We have previously shown that the ratio (RWBP) of incorporation of label from 2-ketoisocaproate (KIC) into the leucine of whole-body protein to the simultaneous incorporation of label from leucine itself into protein is a measure of the nutritional efficiency of KIC as a substitute for leucine. 2. In order to determine whether RWBP can be estimated indirectly from measurement of labelled CO2 excretion, rats were injected orally or intravenously with [4, 5-3H] leucine and either [1-14C] leucine or [1-14C] KIC. Expired CO2 was collected for 6 h. 3. The results show that 9-14% of KIC underwent first-pass oxidation after oral administration. When isotopes were given intravenously, the mean rate of excretion of 14CO2 from KIC, after 20 min, remained 1.8 times the mean rate of excretion of 14CO2 from leucine. 4. Mean RWBP, measured in whole-body protein in rats given isotopes orally or intravenously along with small or large doses of carriers, was the same as mean RWBP estimated from mean cumulative CO2 excretion. 5. We conclude (1) that nutritional efficiency of KIC relative to leucine can be estimated from measurement of labelled CO2 excretion, and (2) that the relative inefficiency of KIC as a substitute for leucine in the rat is attributable to first-pass oxidation of 9-14%(when given orally) and 80% greater susceptibility to systemic oxidation than leucine.