Thelwall Peter E
Newcastle Magnetic Resonance Centre, University of Newcastle, Newcastle upon Tyne, England, UK.
Magn Reson Med. 2007 Jun;57(6):1168-72. doi: 10.1002/mrm.21226.
We present a method for MR detection of (17)O-labeled phosphate groups. The method employs the T(2) relaxivity effect of (17)O on (31)P nuclei to distinguish between (17)O-labeled and unlabeled phosphate groups, and uses spin-echo (SE) acquisitions with RF decoupling at the (17)O frequency to generate (31)P spectra that show only (17)O-labeled phosphate groups. The method provides an alternative to spin-labeling experiments, which are limited to the study of rapidly exchanging phosphate groups by the T(1) relaxation rates of phosphorus nuclei. We demonstrate separation of MR signals from labeled and unlabeled phosphate-containing compounds, and characterization of the T(2) effect of (17)O on phosphate nuclei in (17)O-labeled phosphate groups. Previous (17)O and (18)O phosphate-labeled studies used mass spectrometry or high-resolution MR spectroscopy (MRS) to detect the presence of an isotopic label, which requires ex vivo sample preparation. In our method the detection of (17)O-labeled phosphate is manifested as a large change in (31)P T(2), and thus allows in vivo detection using simple MR methods. Thus this method may have potential for in vivo studies of bioenergetics and the metabolism of phosphate-containing compounds.
我们提出了一种用于磁共振（MR）检测（17）O标记磷酸基团的方法。该方法利用（17）O对（31）P原子核的T（2）弛豫效应来区分（17）O标记的和未标记的磷酸基团，并使用在（17）O频率下进行射频去耦的自旋回波（SE）采集来生成仅显示（17）O标记磷酸基团的（31）P谱。该方法为自旋标记实验提供了一种替代方法，自旋标记实验通过磷原子核的T（1）弛豫速率仅限于研究快速交换的磷酸基团。我们展示了来自标记和未标记含磷化合物的MR信号的分离，以及（17）O对（17）O标记磷酸基团中磷酸原子核的T（2）效应的表征。先前的（17）O和（18）O磷酸标记研究使用质谱或高分辨率磁共振波谱（MRS）来检测同位素标记的存在，这需要离体样品制备。在我们的方法中，（17）O标记磷酸的检测表现为（31）P T（2）的大幅变化，因此可以使用简单的MR方法进行体内检测。因此，该方法可能在生物能量学和含磷化合物代谢的体内研究中具有潜力。
