Hepatobiliary excretion of dipyrrinone sulfonates in Mrp2-deficient (TR(-)) rats.

The biliary excretion of the sodium salts of 8-(2-ethanesulfonic acid)-3-ethyl-2,7,9-trimethyl-1,10-dihydro-11H-dipyrrin-1-one (xanthosulfonic acid) and a fluorescent analogue (8-desethyl-N,N'-carbonyl-kryptopyrromethenone-8-sulfonic acid) was compared in Mrp2-deficient (TR(-)) and normal rats. Both organic anions were excreted rapidly in bile in Mrp2-deficient rats, but the biliary excretion of the fluorescent sulfonate was impaired relative to normal controls. The rat clearly has efficient Mrp2-independent mechanisms for biliary efflux of these anions that are not used by bilirubin or its mono- and diglucuronides.