Arterial KIC as marker of liver and muscle intracellular leucine pools in healthy and type 1 diabetic humans.
Arterial KIC as marker of liver and muscle intracellular leucine pools in healthy and type 1 diabetic humans.
复制标题
动脉 KIC 作为健康人和 1 型糖尿病人肝脏和肌肉细胞内亮氨酸库的标记。
DOI：
10.1152/ajpendo.1999.277.2.e238
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Nair,KS
中科院分区：
文献类型：
--
作者：
Barazzoni,R;Meek,SE;Ekberg,K;Wahren,J;Nair,KS
在同位素标记亮氨酸（Leu）作为示踪剂的人类蛋白质转换研究中，血浆酮异己酸（KIC）富集被广泛用作细胞内亮氨酸富集的替代测量。为了测试动脉酮异己酸（A-KIC）是否准确地代表了肝静脉（HV）和股静脉（FV）中亮氨酸的同位素富集，我们测量了24名对照和6名I型糖尿病患者在连续注入l-[1-13C，15N]-Leu后，从HV、FV和股动脉(A)采集的样品中亮氨酸和KIC的富集。研究在糖尿病组进行胰岛素剥夺或胰岛素替代时进行，而在健康对照组中评估生理盐水或三种不同剂量胰岛素输注（0.25、0.50和1 mU⋅kg−1⋅min−1）的效果。正常组A-KIC与HV Leu和FV Leu的基线同位素富集比分别为0.93±0.01和0.94±0.02，糖尿病组分别为1.07±0.04和1.05±0.03（糖尿病组与正常组比较P< 0.01）。胰岛素对两组a - kit / hv Leu比值均无影响，但正常组a - kit / fv Leu比值在胰岛素输注期间降低（P< 0.05）。总之，a - kic是人类不同循环胰岛素水平下HV Leu富集的可靠替代测量。目前的数据支持使用a - kic作为肝蛋白合成的替代前体池。
In human protein turnover studies with isotopically labeled leucine (Leu) as a tracer, plasma ketoisocaproate (KIC) enrichment is extensively used as a surrogate measure of intracellular leucine enrichment. To test how accurately arterial ketoisocaproate (A-KIC) represents leucine isotopic enrichment in the hepatic (HV) and femoral veins (FV), which drain liver and muscle beds, we measured Leu and KIC enrichments in samples collected from HV, FV, and femoral artery (A) in 24 control and 6 type I diabetic subjects after a primed, continuous infusion ofl-[1-13C,15N]-Leu. Studies were performed during insulin deprivation or insulin replacement in the diabetic group, whereas the effect of normal saline or three different doses of insulin infusion (0.25, 0.50, and 1 mU ⋅ kg−1⋅ min−1) were assessed in healthy controls. The ratios of baseline isotopic enrichments of A-KIC to HV Leu and FV Leu were 0.93 ± 0.01 and 0.94 ± 0.02, respectively, in normal subjects and 1.07 ± 0.04 and 1.05 ± 0.03, respectively, in diabetic subjects (P< 0.01, diabetic vs. normal subjects). Insulin did not change A-KIC-to-HV Leu ratios in either group, but the A-KIC-to-FV Leu ratio decreased during insulin infusion in normal subjects (P< 0.05). In conclusion, A-KIC represents a reliable surrogate measure of HV Leu enrichment at different levels of circulating insulin in humans. The present data support the use of A-KIC as a surrogate precursor pool for hepatic protein synthesis.