Lithium distribution in red blood cells and plasma: NMR studies of rat blood.
To understand the interaction of lithium (Li+) with a coadministered drug in both the blood and the brain, we have treated rats with either Li+ alone or Li+ and a codrug. In this paper we address the important problem of quantitation of intra and extracellular Li+ ion contents in blood by the 7Li-NMR technique and the use of a shift reagent (SR). Although Li+ can be studied by atomic absorption techniques, these techniques involve tedious separation of intra- and extracellular components prior to chemical analysis. Magnetic resonance studies on rat blood, in the dose range of 0.5 to 10 meq/kg, indicate that the intracellular red blood cell Li+ predominates in the lower dose range of 0.5-1.0 meq/kg. As the lithium dose increases, a significantly larger amount of Li+ accumulates in the extracellular volume. Our studies on a number of animals at various doses of LiCl indicate that 7Li-NMR of blood samples provide a reliable, noninvasive quantification of red blood cell and plasma Li+ concentrations. The NMR method was further used to study the effect of coadministered drugs such as thioridazine on the intra- and extracellular Li+ concentration of RBCs.
Ramaprasad
S
S
Department of Radiology, University of Arkansas for Medical Sciences, Little Rock 72205, USA. SRAMAPRASAD@LIFE.UAMS.EDU
Robbins
V W
VW
D000818:Animals; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D004912:Erythrocytes / Q000378:metabolism*; D008094:Lithium / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D010949:Plasma / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013881:Thioridazine / Q000008:administration & dosage
D014150:Antipsychotic Agents; D008094:Lithium; D013881:Thioridazine