The expression of P-glycoprotein (P-gp) and canalicular multispecific organ
ic anion transporter (cMOAT or,Mrp2) was evaluated by Western blotting anal
sis of rat tissues isolated following daily administration (1 mg kg(-1) da
y(-l)) of dexamethasone over 4 days, Dexamethasone rapidly increased P-gp e
xpression more than 4.5- and 2-fold in liver and lung, respectively, while
it If as decreased 40% in kidney. cMOAT expression was increased 2-fold in
liver and kidney following dexamethasone treatment. The levels of both prot
eins returned to control values by 6 days after the conclusion of dexametha
sone administration, These results indicate that dexamethasone ran modulate
P-gp and cMOAT expression in specific rat tissues and may have significant
relevance for patients treated with desamethasone as a single agent or in
combination therapy with other drugs. (C) 1999 Federation of European Bioch
emical Societies.