The Renal Excretion of Bilirubin in Dogs with Obstructive Jaundice*

Abstract

The renal excretion of bilirubin was studied in dogs with obstructive jaundice induced by common bile duct ligation. The administration of conventional inhibitors and competitors of tabular secretory processes did not cause any decrease in urinary bilirubin excretion. Several of the agents, having in common a considerable binding to plasma proteins themselves, caused an increase in urinary bilirubin excretion. This phenomenon was attributed to displacement of conjugated bilirubin from its carrier plasma proteins by these organic anions. Stop-flow studies showed a peak in the bilirubin curve at the glomerular level, which was interpreted as arising from glomerular filtration of protein-bound bilirubin during ureteral occlusion. A small distal peak may represent a secretory locus of modest capacity, but has not been demonstrated consistently. When the induction of partial ureteral obstruction caused a greater decrease of glomerular filtration rate than renal plasma flow, bilirubin clearance was found to parallel the former closely and to diverge from the latter. These studies suggest predominance of glomerular filtration over tabular secretion in the renal excretion of bilirubin.