magnetic resonance. (NMR), with use of aqueous shift reagent, has made ... NMR theory of sodium relaxation in biological media. (10, 11). Materials and Methods .... (o.d.). NMR tube. The inner tube contained an external reference solution,.
CLIN. CHEM. 32/1,
104-107
(1986)
lntra-Erythrocytic Sodium in Uremic Patients, as Determined Resolution” 23Na Nuclear Magnetic Resonance Montl,1
Jean-Pierre
Philippe
Gallice,1 Aim#{233} Crevat,”3
El Mehdl,2
Mohamed
claude
by “High-
Durand,2
and Antoine
Murleasco2 nuclear magnetic resonance with aqueous shift reagent has made it possible to determine intracellular sodium concentrations in living erythrocytes. We applied this technique to samples from 16 healthy subjects and 41 uremic patients. The results seem to show distinct populations among the latter. Classically, two different relaxation times are obtained for intracellular sodium in biological media, according to relaxation NMR theory. Some patients, however, exhibit abnormal results that cannot be accounted for by this theory. The use of Na
Some uremic patients reportedly have above-normal sodium concentrations in their erythrocytes (1-3), as determined with “classical” analytical techniques such as flame photometry. However, the traditional methods have the serious drawback of requiring cell lysis if one is to distinguish the intraand extracellular sodium content. Microelectrodes can provide continuous recording of intracellular sodium, but they are difficult to use with many cell types. More recently, Na nuclear magnetic resonance (NMR), with use of aqueous shift reagent, has made it possible to resolve distinct signals for intraand extracellular sodium in intact erythrocytes (4-9). Therefore, the intracellular concentration of sodium in living erythrocytes can be determined with the same accuracy as by flame photometry (6). Moreover, by using intact erythrocytes, a dynamic study of the movement of sodium through the erythrocyte membrane can be considered, of especial interest in the case of uremic patients. As a first step in the study of these phenomena, we measured the intra-erythrocytic concentration of sodium in uremic patients by an NMR technique and conclude that the results can be resolved into two populations. Moreover, some uremic patients apparently exhibit intracellular mNa N?vlB resonances different from what would be predicted according to classical NMR theory of sodium relaxation in biological media (10, 11).
Materials
and Methods
Patients. We studied 41 patients-18 women and 23 men, mean age 56 (SD 15) years, mean body weight 61 (SD 12) kg, each of whom was being treated by dialysis two or three times a week for 6 (SD 2) h. These were selected from 150 patients with chronic renal failure of various etiologies, who were being treated by hemodialysis. We also studied 16 ostensibly healthy control subjects. Sample prepa ration. Freshly drawn heparinized blood was centrifuged (1700 x g for 10 mm), the plasma was removed, and the cells were washed three times with about five volumes of an ultrafiltrate (see below) of each subject’s ‘Laboratoire de Biophysique, Facult#{233} de Pharmacie, Universito d’Aix-Marseille II, 27 Boulevard Jean-Moulin, 13385 Marseille Cedex 5, France. 2Service de N#{233}phrologie,HSpital Saints Marguerite, Marseille, France. 8Addreas correspondence to this author. Received July 19, 1985; accepted October 1, 1985. 104
CLINICAL CHEMISTRY,
Vol. 32, No. 1, 1986
plasma. For the final wash, we used a modified ultrafiltrate, to which we had added the shift reagent, dysprosium tripolyphosphate (Dy(PPP1)271. The final concentration of this reagent was varied between 2 and 4 mmol/L, to separate the resonances for intra- and extracellular sodium sufficiently for the two peaks to be accurately integrated. Finally, after the last centrifugation, we discarded the supernate (7.3
