An analysis of intracellular 23Na relaxation using the double-quantum filtered NMR signal from the perfused rat salivary gland.
The intracellular sodium of the perfused rat mandibular salivary gland was measured by double-quantum filtered 23Na-NMR spectroscopy at 2.34, 4.7 and 8.45 T. Biexponential relaxation of the intracellular 23Na signal was observed, and its intensity was increased by administration of acetylcholine with ouabain at 25 degrees C. The transverse and longitudinal relaxation rate constants were determined by the 'transverse experiment' (D-90 degrees-tau/2-180 degrees-tau/2-90 degrees-delta-90 degrees-acquire) and the 'longitudinal experiment' (D-180 degrees-tau-54.7 degrees-delta-90 degrees-acquire), respectively. From observed dependencies on B0 and temperature (5-37 degrees C), a possibility of exchange between two populations of intracellular Na+ was suggested. A small fraction of Na+ is in the slow-motion condition (with a quadrupole coupling constant of approx. 1.75 MHz and a correlation time of 6 x 10(-8) s). The major portion of intracellular Na+ is in the extreme narrowing condition with a transverse relaxation rate constant of approx. 100 s-1, which corresponds to a viscosity of approx. 5 cP.
Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
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Seo
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Rooney
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Murakami
D000818:Animals; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012469:Salivary Glands / Q000737:chemistry*; D012964:Sodium / Q000032:analysis*; D013696:Temperature
D012964:Sodium