title: Dietary beta-carotene is taken up by blood plasma and leukocytes in dogs.
abstract: beta-Carotene uptake by blood plasma and leukocytes was studied in mature beagle dogs. In expt. 1, dogs were fed once orally with 0, 50, 100 or 200 mg of beta-carotene and their blood was sampled at 0, 1. 5, 3, 6, 10, 18 and 24 h. Plasma beta-carotene concentrations increased dose-dependently to peak at 6 h postfeeding. Concentrations decreased rapidly thereafter, showing a half-life of 3 to 4 h. In expt. 2, dogs were given daily doses for seven consecutive days with 0, 12.5, 25, 50 or 100 mg beta-carotene. Plasma beta-carotene concentrations increased dose-dependently; concentrations after the last dose were two- to fourfold higher than after the first dose. In expt. 3, dogs were fed 0, 50 or 100 mg beta-carotene daily for 30 d. beta-Carotene was elevated in lymphocytes and neutrophils in supplemented dogs. Furthermore, beta-carotene was taken up by the cytosol, mitochondria, microsomes (lymphocytes and neutrophils) and nuclei (lymphocytes only), proving that dogs can absorb beta-carotene. beta-Carotene is taken up by subcellular organelles of blood lymphocytes and neutrophils and in the plasma and leukocytes beta-carotene may have physiological importance as it relates to immunity in dogs. Uptake kinetics indicated that dogs are not an appropriate animal model for studying beta-carotene absorption and metabolism in humans.
authors.affiliation: Department of Animal Sciences, Washington State University, Pullman, Washington, USA.
authors.forename: B P
authors.initials: BP
authors.lastname: Chew
authors.forename: J S
authors.initials: JS
authors.lastname: Park
authors.forename: B C
authors.initials: BC
authors.lastname: Weng
authors.forename: T S
authors.initials: TS
authors.lastname: Wong
authors.forename: M G
authors.initials: MG
authors.lastname: Hayek
authors.forename: G A
authors.initials: GA
authors.lastname: Reinhart
mesh_terms: D000818:Animals; D004285:Dogs / Q000378:metabolism*; D005260:Female; D007962:Leukocytes / Q000378:metabolism*; D008954:Models, Biological; D009504:Neutrophils / Q000378:metabolism; D019207:beta Carotene / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D019207:beta Carotene