The relationship between biliary secretion of bilirubin and glutathione in the rat

The relationship between biliary secretion of bilirubin and glutathione was investigated by infusing bilirubin solution (200 nmol/min/100 g body wt) into Sprague-Dawley rats and measuring bilirubin and glutathione in the bile. Hepatic glutathione level, when modified between the range of 1–10 μmol/g liver wt, did not affect biliary maximal secretory rate (Tm) of bilirubin (80 nmol/min/100 g body wt). However, when biliary secretion of bilirubin exceeded 10 mM or 30 nmol/min/100 g body wt, biliary secretion of glutathione was markedly impaired while the bile flow remained relatively constant. Thus, bilirubin impaired the biliary secretion of glutathione selectively compared to its effect on bile formation. The results indicate that the mechanisms of biliary secretion of the two physiological substances, bilirubin and glutathione, are closely related.