title: Macroautoradiographic study of the distribution and excretion of 14C-pentobarbitone in rats pretreated with phenobarbitone.
abstract: The distribution and excretion of pentobarbitone were studied, using macroautoradiography, in two groups of rats at times ranging from 1 min to 70 min after the i.v. injection of 100 muCi given as 30 mg/kg of 14C-pentobarbitone. In a control group, the carbon-14 concentration (concentration of pentobarbitone) in the brain remained always greater than that in heart blood (unchanged pentobarbitone and metabolites). In a group subjected to enzyme induction (pretreated with phenobarbitone), however, the carbon-14 concentration in the brain exceeded that in the heart blood initially and then decreased rapidly. In the induced group, the carbon-14 concentration in the urine and small intestine (almost all of which was metabolites) increased with time. In particular, 70 min after the injection, the carbon-14 concentration in the small intestine of the induction group was twice that of the control group. It was concluded that in the induction group the rapid decrease in carbon-14 concentration in the brain was mainly a result of an increase in the metabolic breakdown of pentobarbitone in the liver.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism; D004790:Enzyme Induction; D007421:Intestine, Small / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D010424:Pentobarbital / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D010424:Pentobarbital; D010634:Phenobarbital