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Model to estimate in vivo enrichment of beef muscle and liver with 14 C‐vitamin B12 ( 14 C‐B12)
Author(s) -
Garrod Marjorie G,
Johnson Heidi A,
Calvert Christopher C,
Allen Lindsay H,
Green Ralph,
Miller Joshua W
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.865.5
Subject(s) - vitamin b12 , in vivo , bioavailability , chemistry , zoology , kinetics , absorption (acoustics) , endocrinology , medicine , biochemistry , biology , pharmacology , microbiology and biotechnology , materials science , physics , quantum mechanics , composite material
Beef enriched in vivo with 14 C‐B12 may be used for assessing B12 bioavailability and absorption in humans. However, B12 transfer rates between plasma and tissues in bovines are not well characterized. We created a model of B12 kinetics based on data collected from two 500 lb calves: calf 1 received two I.V. pulse doses of 14 C‐B12 (7.5 μg, 250 nCi/dose) given 24h apart; calf 2 received a continuous infusion of 14 C‐B12 (22.5 μg, 750 nCi) for 21d using an Alzet pump. 14 C content of plasma, liver and muscle was determined by accelerator mass spectrometry. The model is composed of 4 state variables representing B12 pools in blood, liver, muscle, and other tissues. Exchanges between pools were predicted based on mass action kinetics. Using pulse dose data, uptake rates from plasma into muscle and liver were concentration dependent and estimated to be 5.5%/d and 3.9%/d, respectively. Using continuous infusion data, uptake rates from plasma into muscle and liver were concentration independent and estimated to be 0.072 nmol/d and 0.141 nmol/d, respectively. Model estimates of 14 C‐B12 accumulation in liver and muscle were within 30% of measured values. SDs of the estimated exchange rates were low indicating rate predictions were unique. This model can provide estimates of B12 enrichment in meat and liver using different dosing protocols. Funding: National Cattlemen's Beef Association