title: Effects of dietary magnesium deficiency on thallium-20 1 kinetics and distribution in rat myocardium: concise communication.
abstract: Kinetics and distribution of TI-201 were studied in myocardium of rats with chronic dietary induced Mg deficiency. Rats were fed the Mg-deficient diet for 30 days and were then injected intravenously with 0.2 mCi of TI-201. Comparable control animals were fed a standard laboratory diet. One-half hour after injection, rats were killed and a segment of myocardium was washed with nonradioactive Krebs solution in a special chamber. Radioactivity in the tissue was recorded continuously for 1 hr. A three-compartment model (extracellular, main intracellular, and subcellular) was found to describe adequately the kinetics of TI-201. In myocardium of Mg-deficient animals, significant changes in values of transport rate constants and compartment sizes for TI-201 indicated a moderate decrease in extracellular compartment and a threefold enlargement in subcellular compartment (presumably mitochondrial) at the expense of the main intracellular compartment, which underwent a marked reduction. Bulk TI-201 uptake in myocardium of Mg-deficient rats was unchanged. The findings are interpreted as being consistent with mitochondrial alterations reported in Mg-deficient animals. Clinical implications are discussed.
mesh_terms: D000818:Animals; D001692:Biological Transport; D003327:Coronary Disease / Q000000981:diagnostic imaging; D004032:Diet; D006321:Heart / Q000000981:diagnostic imaging*; D007700:Kinetics; D008274:Magnesium; D008275:Magnesium Deficiency; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011868:Radioisotopes / Q000378:metabolism; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D013793:Thallium / Q000378:metabolism*
chemical_list: D011868:Radioisotopes; D013793:Thallium; D008274:Magnesium