TY - JOUR
T1 - A physiologically based toxicokinetic model for dietary uptake of hydrophobic organic compounds by fish
T2 - I. Feeding studies with 2,2,′, 5,5′-tetrachlorobiphenyl
AU - Nichols, John W.
AU - Fitzsimmons, Patrick N.
AU - Whiteman, Frank W.
AU - Dawson, Timothy D.
PY - 2004/2
Y1 - 2004/2
N2 - A physiologically based toxicokinetic (PBTK) model was developed to describe dietary uptake of hydrophobic organic compounds by fish. The gastrointestinal (GI) tract was modeled using four compartments corresponding to the stomach, pyloric ceca, upper intestine, and lower intestine, and the lumenal volume of each compartment was allowed to change in time as a function of bulk flow down the GI tract and (for the pyloric ceca and upper intestine) nutrient uptake. The model was developed using data from rainbow trout that were fed a single meal of 60-day-old fathead minnows contaminated with [UL-14C] 2,2′,5,5′-tetrachlorobiphenyl ([14C] PCB 52). Chemical partitioning coefficients for the gut contents and tissues were adjusted to account for changes in chemical affinity associated with uptake of dietary lipid. Permeability constants for the absorbing gut segments were then fitted by modeling to measured [14C] PCB 52 concentrations in gut contents and tissues. The model accurately describes observed patterns of gastric evacuation and bulk flow of digesta, the concentration time course for [14C] PCB 52 in contents and tissues of the GI tract, and [14C] PCB 52 distribution to other major tissues. Most of the [14C] PCB 52 was taken up in the pyloric ceca and upper intestine during the period of peak lipid absorption. It is concluded, however, that a kinetic limitation acting along the entire length of the GI tract resulted in a chemical disequilibrium between feces and tissues of the lower intestine.
AB - A physiologically based toxicokinetic (PBTK) model was developed to describe dietary uptake of hydrophobic organic compounds by fish. The gastrointestinal (GI) tract was modeled using four compartments corresponding to the stomach, pyloric ceca, upper intestine, and lower intestine, and the lumenal volume of each compartment was allowed to change in time as a function of bulk flow down the GI tract and (for the pyloric ceca and upper intestine) nutrient uptake. The model was developed using data from rainbow trout that were fed a single meal of 60-day-old fathead minnows contaminated with [UL-14C] 2,2′,5,5′-tetrachlorobiphenyl ([14C] PCB 52). Chemical partitioning coefficients for the gut contents and tissues were adjusted to account for changes in chemical affinity associated with uptake of dietary lipid. Permeability constants for the absorbing gut segments were then fitted by modeling to measured [14C] PCB 52 concentrations in gut contents and tissues. The model accurately describes observed patterns of gastric evacuation and bulk flow of digesta, the concentration time course for [14C] PCB 52 in contents and tissues of the GI tract, and [14C] PCB 52 distribution to other major tissues. Most of the [14C] PCB 52 was taken up in the pyloric ceca and upper intestine during the period of peak lipid absorption. It is concluded, however, that a kinetic limitation acting along the entire length of the GI tract resulted in a chemical disequilibrium between feces and tissues of the lower intestine.
KW - Dietary uptake
KW - Fish
KW - Physiologically based model
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U2 - 10.1093/toxsci/kfh033
DO - 10.1093/toxsci/kfh033
M3 - Article
C2 - 14657515
AN - SCOPUS:1342310168
SN - 1096-6080
VL - 77
SP - 206
EP - 218
JO - Toxicological Sciences
JF - Toxicological Sciences
IS - 2
ER -