Identification of cytochrome P-450 isozymes involved in the hydroxylation of dantrolene by rat liver microsomes.
The role of individual rat liver cytochrome P-450 isozymes in the metabolism of the skeletal muscle relaxant, dantrolene, was studied. Following incubation of dantrolene with hepatic microsomes from 3-methylcholanthrene-treated rats, two major hydroxylated metabolites were identified. Using inhibitory antibodies specific for individual cytochrome P-450 isozymes, cytochromes P-450 1A1, 1A2, and 3A were identified to be involved in dantrolene hydroxylations. In liver microsomes from 3-methylcholanthrene-treated rats, antibodies specific for cytochrome P-450 1A1 and 1A2 inhibited hydroxylation of dantrolene by 60% and 20%, respectively. Kinetics studies using these microsomes showed that dantrolene hydroxylation was biphasic with a low KM (0.06-0.08 microM) and high KM (5-7 microM). Cytochrome P-450 1A1 was responsible for the low KM hydroxylation of dantrolene, whereas cytochrome P-450 1A2 was responsible for the high KM. In hepatic microsomes from pregnenolone-16 alpha-carbonitrile-treated rats, an antibody specific for cytochrome P-450 3A completely inhibited the formation of 5-hydroxydantrolene, the major metabolite formed by these microsomes.
Jayyosi
Z
Z
Centre du Médicament, Université de Nancy I.
Villoutreix
J
J
Ziegler
J M
JM
Batt
A M
AM
De Maack
F
F
Siest
G
G
Thomas
P E
PE
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000378:metabolism*; D003620:Dantrolene / Q000378:metabolism*; D004790:Enzyme Induction; D005260:Female; D006900:Hydroxylation; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D000906:Antibodies; D065607:Cytochrome P-450 Enzyme Inhibitors; D007527:Isoenzymes; D003577:Cytochrome P-450 Enzyme System; D003620:Dantrolene