Induction profiles of P450 in rat liver microsomes by pyrazole or methylpyrazole

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5176960

Krikun, G; Cederbaum, A I

Rats were injected for 2-3 days with pyrazole (P) or 4-methylpyrazole (MP) potent inhibitors of alcohol dehydrogenase. While P treatment induced a P450 isozyme with MW 52,000 as seen on SDS gels, MP induced 2 or 3 P450s. One of the P450s induced by MP appeared to be similar to the one increased by P treatment. The increase of 2-3 bands by MP correlated with a two fold increased in total P450 content. Microsomes from the P treated rats displayed increased activity (per mg protein or per nmole P450) with aniline, p-nitroanisole, dimethylnitrosamine (low Km DMN) and ethanol as substrates, but not with aminopyrine, ethoxycoumarin or DMN (high Km). A stereochemical preference for + 2-butanol over the -isomer was also observed. Kinetic experiments indicated that P treatment increased the Vmax for ethanol, aniline and + 2-butanol. These properties are similar to those found after chronic ethanol treatment. MP treatment resulted in an increased in the oxidation of all the drugs and alcohols tested, primarily due to the increase in content of P450. In analogy to results with P, MP treatment also resulted in stereochemical preference for + vs -2-butanol, and increased turnover numbers with aniline and p-nitroanisole. However in contrast to P, no increase in turnover number with ethanol, + 2-butanol or DMN (low Km) was found after MP treatment. It is probable that these divergent effects are due to the induction of several isozymes, one of which has properties similar to that induced by P. Thus, P induces a P450 similar to that induced by ethanol whereas MP induces that isozyme in addition to others.

• Research Organization: Mount Sinai School of Medicine, New York, NY
• OSTI ID: 5176960
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

560301* -- Chemicals Metabolism & Toxicology-- Cells-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALCOHOLS
ANIMALS
AZOLES
BIOLOGICAL EFFECTS
BODY
CELL CONSTITUENTS
COMPARATIVE EVALUATIONS
DIGESTIVE SYSTEM
ENZYME INHIBITORS
ENZYMES
ETHANOL
GLANDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
LIVER
MAMMALS
MICROSOMES
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
ORGANS
OXIDOREDUCTASES
PYRAZOLES
RATS
RODENTS
STEREOCHEMISTRY
VERTEBRATES