Phenolsulphonphthalein conjugation and biliary excretion in the rat: influence of phenobarbital and 3-methylcholanthrene.
The effect of phenobarbital and 3-methylcholanthrene pretreatment on the biliary excretion of phenolsulphonphthalein (PSP) was investigated in male Wistar rats. The dye was injected at a single dose of 200 mumol/kg body wt. About 20% of the compound was excreted as a glucuronide in the controls, the liver UDP-glucuronyltransferase activity toward PSP being 0.064 +/- 0.005 nmol.min-1.mg protein-1. Treatment for two weeks with phenobarbital (354 mumol.kg body wt-1.day-1) caused a transient increase in conjugated and unconjugated PSP excretion, but glucuronyltransferase activity was not modified. 3-Methylcholanthrene pretreatment for 4 days (75 mumol.kg body wt-1.day-1) also enhanced biliary excretion of the dye, but the increase corresponded only to the glucuronide and glucuronyltransferase activity was significantly enhanced by 20%. Our data indicate that not only the rate of biotransformation but also other factors could be responsible for increased PSP biliary excretion following administration of microsomal enzyme inducers.
Collado
P S
PS
Department of Physiology and Pharmacology, University of Salamanca, Spain.
Muñoz
M E
ME
Esteller
A
A
Gonzalez
J
J
D000818:Animals; D001646:Bile / Q000187:drug effects* / Q000378:metabolism; D001711:Biotransformation / Q000187:drug effects; D005965:Glucuronates / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D010634:Phenobarbital / Q000494:pharmacology*; D010635:Phenolphthaleins / Q000493:pharmacokinetics*; D010637:Phenolsulfonphthalein / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
D005965:Glucuronates; D010635:Phenolphthaleins; D008748:Methylcholanthrene; D014453:Glucuronosyltransferase; D010637:Phenolsulfonphthalein; D010634:Phenobarbital