Molybdenum metabolism in men with increasing molybdenum intakes: changes in kinetic parameters.
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.
Thompson
K H
KH
United States Department of Agriculture/Agricultural Research Station, Western Human Nutrition Research Center, Presidio of San Francisco, California 94129-0997, USA.
Scott
K C
KC
Turnlund
J R
JR
D000328:Adult; D006801:Humans; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D008982:Molybdenum / Q000378:metabolism*
D008982:Molybdenum