Sodium-23 NMR relaxation times in body fluids

✍ Scribed by Hadassah Shinar; Gil Navon

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 471 KB
• Volume: 3
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910030613

✦ Synopsis

23Na longitudinal and transverse NMR relaxation times were measured in human serum, plasma, cerebrospinal fluid (CSF), and solutions of plasma proteins. The magnetization decay curves could not be resolved into two exponentiak. A procedure to extract quantitative information from the measured relaxation rates in such a case was developed. The relaxation times of Z3Na in serum and plasma were analyzed in terms of the different contributions from free Na+, Na' bound to small molecules, and Na+ bound to various protein fractions in these body fluids. While TI is essentially that of free Na+ in a solution which is slightly more viscous than salt solution, Tz is influenced by binding to proteins with the largest contribution from serum albumin. The effect of binding to small molecules on TI and Tz is negligible. From measurements ofthe relaxation times at several magnetic field strengths a rotational correlation time of Na+ bound to serum albumin of 16 +. 6 ns was obtained.

The fraction of bound Na+ in serum and plasma was roughly estimated as 0.02% of the total sodium. The relaxation times in cerebrospinal fluid are very similar to those of NaCl SOlUtiOn. 8 1986 Academic Press Inc.