Practical application of NMR spectra of 129Xe dissolved in red blood cell

Abstract The 129 Xe NMR spectra in red blood cell (RBC) were investigated in vitro focusing upon temperature dependence and the magnetization transfer (MT) experiment. 129 Xe signals were observed at 192 and 201 ppm in the RBC solution, which were assigned to 129 Xe dissolved in saline and RBC phases, respectively. A presence of the third peak was evidenced by the MT experiment, in which a pre-saturation around 210–220 ppm caused a decrease in the intensity of the 192-ppm peak. To examine the applicability of the 129 Xe NMR spectra index for the detection of physiological conditions, the temperature dependence of the chemical shift was studied precisely and accurately in the RBC solution. The multinuclear internal reference method was adopted to express the chemical shift on an absolute frequency scale. The temperature dependence was proved to be non-linear and approximated by a convex curve for the 192 ppm peak, whereas it was linear for the 201-ppm peak. The temperature coefficient amounted to as much as 0.2 ppm/°C (5 °C/ppm) for the 129 Xe signal in RBC. A quite similar coefficient was observed for the separation of 192 and 201 ppm peaks, which was measured simply without the adoption of an absolute frequency scale and will be suited for practical application.