用~2H-苯丙氨酸示踪和GC-MS分析技术测定人体内苯丙氨酸-4-羟化酶活力

IN VIVO DETERMINATION OF PHENYLALANINE HYDROXYLASE ACTIVITY IN CIRRHOTIC PATIENTS WITH ~2H-PHENYLALANINE

摘要: 采用~2H-苯丙氨酸(~2H-Phenylalanine)负荷试验,对8例正常人和23例肝硬化病人(8例代偿性,15例失代偿)的苯丙氨酸羟化酶活力进行了测定。单次静脉注射L-~2H-Phe(10mg/kg体重)或DL-~2H-Phe(20mg/kg体重)后,用GC-MS法分析血浆~2H-Phe和~2H-Tyrosine的丰度。苯丙氨酸羟化酶的活力用4种方式表达:①~2H-Tyr丰度的上升斜率。②~2H-Tyr/~2H-Phe丰度比的上升斜率。③~2H-Tyr丰度时相曲线下的面积。④~2H-Tyr/~2H-Phe丰度比时相曲线下的面积。实验结果表明:代偿性肝硬化病人的苯丙氨酸羟化酶活力低于正常人,失代偿肝硬化病人的该酶活力又低于代偿性肝硬病人。

Abstract: The phenylalanine hydroxylase activities of 23 cirrhotic patients (8 compensated and 15 decompensated) and 8 normal adults were measured with a deuterated phenylalanine loading test. After a single iv injection of 10mg/kg labeled L-phenylalanine or 20 mg/kg labeled DL Phe,the abundances of plasma Phe and Tyrosine were analysed with GC-MS. The activities of phenylalanine hydroxylase were estimated by ①the slope of Tyr abundance curve, ②the slope of Tyr/Phe abundance ratio curve, ③the area under Tyr abundance curve, and ④the area under Tye/Phe abundance ratiocurve. The results revealed that the activity of phenylalanine hydroxylase was impaired in cirrhotic patients and the impairment was more severe in decompensated than in compensated cirrhosis.