Assay of sodium-lithium countertransport rate by direct measurement of erythrocyte lithium concentrations.
A method is described for the in-vitro measurement of erythrocytic sodium-lithium countertransport rate (SLC) by direct assay of intra-erythrocytic lithium (Li) concentrations in Li loaded cells during controlled Li efflux. Bicarbonate stimulated erythrocytic Li loading to an approximate intracellular concentration of 3 mmol/l can be achieved within 4 min. Maximum SLC rates are achieved at intra-erythrocytic concentrations greater than 2.5 mmol/l. Lithium efflux is linear over 0-60 min, and independent of pH change. The within-batch coefficient of variation for positive displacement pipetting of Li loaded erythrocytes is 2.8%. Storage of erythrocytes in isosmotic MgCl2 for 24 h had no effect on the SLC. Intra-individual coefficient of variation for SLC was less than 6%. The reference range for Caucasian subjects (n = 43) was 0.14-0.49 mmol Li +/l erythrocytes/h.
Siebers
R W
RW
Department of Medicine, Wellington Clinical School of Medicine, New Zealand.
Maling
T J
TJ
D017920:Antiporters; D002352:Carrier Proteins / Q000097:blood*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008094:Lithium / Q000097:blood*; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride
D017920:Antiporters; D002352:Carrier Proteins; C045885:sodium-lithium countertransporter; D015636:Magnesium Chloride; D008094:Lithium; D008274:Magnesium