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Development of an inhalation physiologically based pharmacokinetic (PBPK) model for 2,2, 4-trimethylpentane (TMP) in male Long-Evans rats using gas uptake experiments.

Inhalation toxicology (2009-11-20)
Hisham A El-Masri, Sean Dowd, Rex A Pegram, Randy Harrison, Sisouphanh J Yavanhxay, Jane Ellen Simmons, Marina Evans
ABSTRACT

2,2,4-Trimethylpentane (TMP) is a volatile colorless liquid used primarily to increase the octane rating of combustible fuels. TMP is released in the environment through the manufacture, use, and disposal of products associated with the gasoline and petroleum industry. Short-term inhalation exposure to TMP (< 4 h; > 1000 ppm) caused sensory and motor irritations in rats and mice. Like many volatile hydrocarbons, acute exposure to TMP may also be expected to alter neurological functions. To estimate in vivo metabolic kinetics of TMP and to predict its target tissue dosimetry during inhalation exposures, a physiologically based pharmacokinetic (PBPK) model was developed for the chemical in Long-Evans male rats using closed-chamber gas-uptake experiments. Gas-uptake experiments were conducted in which rats (80-90 days old) were exposed to targeted initial TMP concentrations of 50, 100, 500, and 1000 ppm. The model consisted of compartments for the closed uptake chamber, lung, fat, kidney, liver, brain, and rapidly and slowly perfused tissues. Physiological parameters were obtained from literature. Partition coefficients for the model were experimentally determined for air/blood, fat, liver, kidney, muscle, and brain using vial equilibration methods. Common to other hydrocarbons, metabolism of TMP via oxidative reactions is assumed to mainly occur in the liver. The PBPK model simulations of the closed chamber data were used to estimate in vivo metabolic parameters for TMP in male Long-Evans rats.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2,2,4-三甲基戊烷, anhydrous, 99.8%
Sigma-Aldrich
2,2,4-三甲基戊烷, ACS reagent, ≥99.0%
Sigma-Aldrich
2,2,4-三甲基戊烷, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.5%
Sigma-Aldrich
2,2,4-三甲基戊烷, suitable for HPLC, ≥99%
Sigma-Aldrich
2,2,4-三甲基戊烷, puriss. p.a., ≥99.5% (GC)
Supelco
2,2,4-三甲基戊烷, analytical standard
Sigma-Aldrich
2,2,4-三甲基戊烷, ReagentPlus®, ≥99%
Sigma-Aldrich
2,2,4-三甲基戊烷, puriss. p.a., ACS reagent, ≥99.5% (GC)
Supelco
密度标准品 692kg/m3, H&D Fitzgerald Ltd. Quality