Validation of red cell sodium-lithium countertransport measurement--influence of different loading conditions
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Validation of red cell sodium-lithium countertransport measurement--influence of different loading conditions. / Besch, W; Schläger, D; Brahm, J; Kohnert, K D.
I: European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies, Bind 33, Nr. 10, 10.1995, s. 715-9.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Validation of red cell sodium-lithium countertransport measurement--influence of different loading conditions
AU - Besch, W
AU - Schläger, D
AU - Brahm, J
AU - Kohnert, K D
PY - 1995/10
Y1 - 1995/10
N2 - Increased sodium-lithium countertransport in erythrocytes from patients with long-standing type I (insulin-dependent) diabetes mellitus has been considered as an early marker of nephropathy. Since the activity and kinetics of the sodium-lithium countertransport may critically depend on loading conditions, this study was aimed at determining sodium-lithium countertransport activity, Michaelis constant Km and maximum velocity Vmax in erythrocytes loaded in two different Li+ solutions. Sodium-lithium countertransport activity was determined in erythrocytes in 8 healthy control subjects after loading with 150 mmol/l LiCl compared with those loaded with 150 mmol/l LiHCO3. Sodium-lithium countertransport activity was similar for both loading procedures, although the erythrocyte lithium content did significantly differ (mean +/- SEM, 7.0 +/- 0.5 for LiCl and 8.9 +/- 0.5 mmol/l of cells for 150 mmol/l LiHCO3). There were no significant changes in the Km and Vmax. Increase of osmolality in efflux media containing 200 and 250 mmol/l NaCl resulted in a negligible shrinking of the red blood cells, not exceeding 2.2%. The main advantage is the short loading time of 15 min for LiHCO3 compared with 3 hours for LiCl. Under these conditions saturating intracellular Li+ concentrations can be obtained much more rapidly than with LiCl loading, thereby minimising alterations of the cell membranes. LiHCO3 loading shortens the experimental time considerably and enables a greater number of samples to be screened from larger population cohorts.
AB - Increased sodium-lithium countertransport in erythrocytes from patients with long-standing type I (insulin-dependent) diabetes mellitus has been considered as an early marker of nephropathy. Since the activity and kinetics of the sodium-lithium countertransport may critically depend on loading conditions, this study was aimed at determining sodium-lithium countertransport activity, Michaelis constant Km and maximum velocity Vmax in erythrocytes loaded in two different Li+ solutions. Sodium-lithium countertransport activity was determined in erythrocytes in 8 healthy control subjects after loading with 150 mmol/l LiCl compared with those loaded with 150 mmol/l LiHCO3. Sodium-lithium countertransport activity was similar for both loading procedures, although the erythrocyte lithium content did significantly differ (mean +/- SEM, 7.0 +/- 0.5 for LiCl and 8.9 +/- 0.5 mmol/l of cells for 150 mmol/l LiHCO3). There were no significant changes in the Km and Vmax. Increase of osmolality in efflux media containing 200 and 250 mmol/l NaCl resulted in a negligible shrinking of the red blood cells, not exceeding 2.2%. The main advantage is the short loading time of 15 min for LiHCO3 compared with 3 hours for LiCl. Under these conditions saturating intracellular Li+ concentrations can be obtained much more rapidly than with LiCl loading, thereby minimising alterations of the cell membranes. LiHCO3 loading shortens the experimental time considerably and enables a greater number of samples to be screened from larger population cohorts.
KW - Adult
KW - Antiporters
KW - Cells, Cultured
KW - Erythrocytes
KW - Humans
KW - Lithium
KW - Reproducibility of Results
KW - Sodium
KW - Time Factors
M3 - Journal article
C2 - 8608193
VL - 33
SP - 715
EP - 719
JO - European Journal of Clinical Chemistry and Clinical Biochemistry
JF - European Journal of Clinical Chemistry and Clinical Biochemistry
SN - 0939-4974
IS - 10
ER -
ID: 94518690