ESTIMATION OF CEREBRAL INTRA- AND EXTRACELLULAR Na^+ CONCENTRATION BY IN VIVO MAGNETIC RESONANCE SPECTROSCOPY WITH SHIFT REAGENT

在核磁共振方法中引入了新的顺磁移动剂，使得在体外区分组织或器官中的细胞内和细胞外离子成为可能。然而，在活体器官中进行这样的测量还没有报道。在本研究中，我们尝试用核磁共振波谱测定沙土鼠脑和骨骼肌中细胞内和细胞外^&lt；23&gt；Na和^1H的含量。如果没有Dy(TTHA)^&lt；3-gt；，则^&lt；23&gt；Na和^1H信号仅被视为单峰。静脉滴注300 mM DY(TTHA)后，血压下降不明显，脑电与核磁共振波谱同步记录。DY(TTHA)3-GT；输注2小时后，~(23)Na和~1H信号分别出现两个峰。未移动的峰反映了细胞内的^&lt；23&gt；Na和^1H信号，而移位的峰反映了细胞外的信号。在脑光谱中，检测到一个代表血管内信号的额外小峰，其强度在注射罂粟碱后增强。这种方法比微电极技术更具优势，因为它是非破坏性的，而且它能够从~1H谱的测量中获得细胞内外的体积信息，其峰值反映了细胞内和细胞外的水量。这项技术显然可用于器官的生理学和病理生理学研究。

The introduction of new paramagnetic shift reagent in the nuclear magnetic resonance (NMR) method has made it possible to distinguish intra- and extracellular ions in tissues or organs in vitro. However, such measurements in organs in vivo have not yet been reported. In the present investigation, we attempted to measure the intra- and extracellular ^<23>Na and ^1H in vivo in the gerbil brain and skeletal muscle by NMR spectroscopy employing the shift reagent, dysprosium triethylenetetraminehexaacetate, Dy(TTHA)^<3->. Without Dy(TTHA)^<3->, the ^<23>Na and ^1H signals were seen only as single peaks. Gradual intravenous infusion of 300 mM DY(TTHA)^<3-> caused little blood pressure reduction and no change in electroencephalogram which was recorded simultaneously with the NMR spectroscopy. After 2 hours of DY(TTHA)^<3-> infusion, the ^<23>Na and ^1H signals were into two peaks, respectively. The unshifted peaks reflected the intracellular ^<23>Na and ^1H signals, whereas the shifted peaks reflected the extracellular signals. In the brain spectra, an additional small peak, which represented intravascular signals, was detected, and its intensity increased after injection of papaverine hydrochloride. The present method is advantageous over the microelectrode technique because of its nondestructiveness and its capability for obtaining intra- and extracellular volume information from measurements of the ^1H spectra, the peaks of which reflect the intra- and extracellular water amounts. The technique is clearly of use for physiological and pathophysiological studies of organs.