Steward M C, Seo Y, Murakami M, Watari H
Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Proc Biol Sci. 1991 Feb 22;243(1307):115-20. doi: 10.1098/rspb.1991.0019.
Rubidium is a good substitute for potassium in many biological systems, and it has been suggested that rubidium-87 nuclear magnetic resonance (87Rb-NMR) spectroscopy could be used to measure K+ fluxes across membranes in intact tissues. To evaluate this possibility, isolated rat mandibular salivary glands were perfused with solutions containing Rb+ in place of K+. The 87Rb signals arising from the intra- and extracellular compartments were first separated by spectral subtraction and then subjected to line-shape analysis. The narrow extracellular signal was a single Lorentzian (line-width 156 Hz), whereas the broader intracellular signal consisted of two Lorentzian components (ca. 530 and 3080 Hz). Double-quantum filtering of the 87Rb signal from the glands revealed two components of transverse relaxation in antiphase (rate constants 1.8 and 13.3 ms-1), showing the probable involvement of quadrupolar interactions in the relaxation of intracellular Rb+. We conclude, therefore, that both line-shape analysis and double-quantum filtering could provide a basis for the measurement of unidirectional K+ fluxes in intact tissues.
在许多生物系统中，铷是钾的良好替代物，有人提出可用铷 - 87核磁共振（87Rb - NMR）光谱法来测量完整组织中钾离子跨膜通量。为评估这种可能性，用含铷离子而非钾离子的溶液灌注分离的大鼠下颌唾液腺。首先通过光谱减法分离细胞内和细胞外区室产生的87Rb信号，然后进行线形分析。狭窄的细胞外信号是单一的洛伦兹峰（线宽156 Hz），而较宽的细胞内信号由两个洛伦兹峰成分组成（约530和3080 Hz）。对来自腺体的87Rb信号进行双量子滤波，揭示了反相横向弛豫的两个成分（速率常数分别为1.8和13.3 ms-1），表明四极相互作用可能参与细胞内铷离子的弛豫。因此，我们得出结论，线形分析和双量子滤波都可为测量完整组织中的单向钾离子通量提供基础。
