活兔脑肌酸激酶动力学的31P磁化转移研究

31P magnetization transfer studies of creatine kinase kinetics in living rabbit brain.

作者信息

Degani H, Alger J R, Shulman R G, Petroff O A, Prichard J W

机构信息

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511.

出版信息

Magn Reson Med. 1987 Jul;5(1):1-12. doi: 10.1002/mrm.1910050102.

DOI:10.1002/mrm.1910050102

PMID:3657491

Abstract

The kinetics of the CK reaction in the living rabbit brain was studied by three 31P magnetization transfer methods: inversion recovery (IR), inversion transfer (IT), and steady-state saturation transfer (SSST). Longitudinal relaxation rates (tau -1) were determined from IR and IT experiments. The values were 0.88 +/- 0.08 s-1 for PCr and 2.45 +/- 0.39 s-1 for gamma-ATP. Analysis of the results of SSST experiments in which gamma-ATP was saturated yielded a forward rate constant kF of 0.53 +/- 0.07 s-1. Upon saturation of PCr no change in the gamma-ATP signal could be detected in SSST. An average reverse rate constant (kR +/- S.D.) of 0.52 +/- 0.04 s-1 was estimated by analyzing IT data from three experiments with selective inversion of gamma-ATP. The standard error of kR was 50%. The average [PCr]/[ATP] of 1.21 +/- 0.16 together with the values of kF and kR yielded a forward-to-reverse flux ratio of 1.23. Within our limits of accuracy this ratio was not significantly different from 1.0, thus suggesting that in the brain the forward and reverse CK fluxes are equal.

摘要

采用三种³¹P磁化转移方法，即反转恢复（IR）、反转转移（IT）和稳态饱和转移（SSST），研究了活兔脑中肌酸激酶（CK）反应的动力学。通过IR和IT实验测定纵向弛豫率（tau -1）。磷酸肌酸（PCr）的值为0.88±0.08 s⁻¹，γ-三磷酸腺苷（γ-ATP）的值为2.45±0.39 s⁻¹。对γ-ATP饱和的SSST实验结果分析得出正向速率常数kF为0.53±0.07 s⁻¹。在PCr饱和时，SSST中未检测到γ-ATP信号的变化。通过分析γ-ATP选择性反转的三个实验的IT数据，估计平均反向速率常数（kR±标准差）为0.52±0.04 s⁻¹。kR的标准误差为50%。平均[PCr]/[ATP]为1.21±0.16，连同kF和kR的值得出正向与反向通量比为1.23。在我们的精度范围内，该比值与1.0无显著差异，因此表明在脑中正向和反向CK通量相等。