Pharmacokinetic profile and placental transfer of a single intravenous injection of [(14)C]chlorpyrifos in pregnant rats.

The pharmacokinetics and placental transfer of a single intravenous dose of 5.0 mg/kg (10 micro Ci/kg) ring-labeled [(14)C]chlorpyrifos were investigated in pregnant Sprague-Dawley rats at 11-13 days of gestation. Three rats were killed at 5, 15 or 30 min, or 1, 2, 4, 8, 12, 18, 24, 36, 48, 72 or 96 h after dosing.

Robustness of MetaNet graph models: predicting control of urea production in humans.

Urea production in human liver was described by a MetaNet graph, a flowchart-like representation of metabolic pathways that includes parameters for the kinetic constants of the constituent enzymes. Formal operations on the graph facilitate the identification of ligand-binding equilibria that participate in feedback regulation in the network of biochemical reactions. The state of the biochemical network is specified by the concentrations of the intermediates.