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Molybdenum metabolism in men with increasing molybdenum intakes: changes in kinetic parameters

1996; American Physiological Society; Volume: 81; Issue: 3 Linguagem: Inglês

10.1152/jappl.1996.81.3.1404

8750-7587

K.H. Thompson, Karen C. Scott, Judith R. Turnlund,

Folate and B Vitamins Research

Molybdenum metabolism was studied in four young men to determine the effect of the amount of dietary molybdenum on molybdenum kinetics. A compartmental model, developed by using data from a study with low dietary molybdenum, was adapted to accommodate five levels of molybdenum. Each level, ranging from 22 to 1,470 micrograms molybdenum/day, was fed for 24 days. Kinetics of absorption and excretion were traced by using 97Mo (intravenous) and 100 Mo (oral) stable-isotope tracers at selected intervals. Urinary and fecal isotope excretion data for 6-day pooled collections were fit to a kinetic model by using SAAM/CONSAM software. Residence times for molybdenum were estimated at 2.4 days in the gastrointestinal tract, 40 min in plasma, from 3.3 to 0.3 days in fast-turnover tissue, and from 63 to 237 days in slow-turnover tissue. As dietary molybdenum increased, residence time decreased in fast-turnover tissue and increased in slow-turnover tissue. The model closely approximated the highly efficient homeostatic mechanisms of molybdenum metabolism over a wide range of intakes.