Induction of a dose-related increase in sulfobromophthalein uptake velocity in freshly isolated rat hepatocytes by phenobarbital
| Autor: | Paul D. Berk, Barry J Potter, Jia-Zhang Ni, Decherd D. Stump, Kathleen Wolfe |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Male
medicine.medical_specialty Bilirubin Michaelis–Menten kinetics Sulfobromophthalein Rats Sprague-Dawley chemistry.chemical_compound Internal medicine Mole medicine Animals Glucuronosyltransferase Chromatography High Pressure Liquid Glutathione Transferase Chromatography Dose-Response Relationship Drug Hepatology Albumin Membrane transport Rats Endocrinology Liver chemistry Phenobarbital Perfusion medicine.drug |
| Zdroj: | Hepatology. 20:1078-1085 |
| ISSN: | 1527-3350 0270-9139 |
| DOI: | 10.1002/hep.1840200441 |
| Popis: | To determine whether phenobarbital affects hepatocellular bilirubin/sulfobromophthalein uptake mechanism, we administered it to male Sprague-Dawley rats, body weight 175 ± 25 gm, at doses of 1 to 75 mg/kg body wt/day for 7 days. Control rats were given an equivalent volume of physiological saline solution. On day 8, hepatocytes were isolated by means of collagenase perfusion, suspended in Hanks' solution without albumin and incubated with high specific activity (3 Ci/mmol) [35S]sulfobromophthalein, which was synthesized in our laboratory and purified by means of a new reverse-phase high-pressure liquid chromatography procedure. The initial uptake rate of sulfobromophthalein was determined at sulfobromophthalein concentrations of 1 to 50 μmol/L with a rapid filtration technique. The maximum uptake velocity and Michaelis constant for sulfobromophthalein uptake at each phenobarbital dose were determined by means of a computer analysis. In control studies, maximum uptake and Michaelis constant were 48.0 ± 16.7 (mean ± S.D.) pmol/50,000 cells/min and 22 ± 4 μmol/L, respectively. Maximum uptake velocity increased linearly with the log of the phenobarbital dose (r = 0.98, p < 0.01), the increase achieving statistical significance at a dose of 3 mg/kg/day. Michaelis constant, however, was essentially unchanged at phenobarbital doses of 50 mg/kg/day or less. The maximal observed increase in maximum uptake velocity of sulfobromophthalein (to 619% of control values) was appreciably greater than the maximal increase in UDP-glucuronyltransferase activity (200% of control) or immunoreactive ligandin concentrations (260% of control) seen in earlier studies, suggesting a direct effect on the plasma membrane transport mechanism. (Hepatology 1994;20:1078–1085). |
| Databáze: | OpenAIRE |
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