NMR relaxation studies of intracellular Na+ in red blood cells.
The state of intracellular Na+ in human and dog erythrocytes was characterized by 23Na-NMR using dysprosium complexes as shift reagents. Intracellular Na+ concentrations were determined using integration of the inner Na+ NMR signals and measurements of the intracellular volume using 59Co-NMR of extracellular Co(CN)3-6. T2 was found to be significantly shorter than T1, indicating some binding to macromolecules. While the longitudinal magnetization decay follows a single exponential, the transverse magnetization could be fitted with a double-exponential function. It was shown that neither the binding to the inner side of the membrane nor binding to hemoglobin contributes to the relaxation enhancement.
D000818:Animals; D004285:Dogs; D004912:Erythrocytes / Q000378:metabolism*; D006454:Hemoglobins / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D012964:Sodium / Q000097:blood*; D013045:Species Specificity; D013816:Thermodynamics
D006454:Hemoglobins; D012964:Sodium