Microtubule modulation of biliary excretion of endogenous and exogenous hepatic lysosomal constituents

R. B. Sewell, S. S. Barham, A. R. Zinsmeister

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Abstract

We tested the hypothesis that hepatocyte microtubules modulate the biliary excretion of endogenous and exogenous constituents of hepatocyte lysosomes. We collected bile via bile fistulas from male rats before and after acute administration of colchicine and vinblastine, agents known to bind to hepatocyte microtubules; rats were then killed and livers were homogenized for biochemical analyses or processed for electron microscopy. Colchicine caused biphasic, parallel alterations in the biliary excretion of three lysosomal enzymes compared with control rats given saline or lumicolchicine; a peak rise in enzyme outputs of approximately 175% at 45-60 min after colchicine administration was followed by a sustained fall to approximately 25% of control values, which persisted for 2-4 h. When hepatocyte lysosomes were prelabeled in vivo by administration of [3H]Triton WR-1339, a nonionic detergent that is sequestered in hepatic lysosomes, the biliary excretion of radiolabel in response to colchicine paralleled the biliary excretion of the three lysosomal enzymes. Vinblastine also induced a biphasic response in biliary lysosomal enzyme output that was similar to that produced by colchicine administration. Morphometric analysis of electron micrographs of rat livers demonstrated changes in the number of lysosomelike vesicles in the vicinity of bile canaliculi after colchicine and vinblastine administration; the initial increase in lysosomal enzyme secretion was associated with a significant decrease in the number of pericanalicular lysosomes after both agents, while the subsequent decrease in enzyme secretion coincided with an increase in the number of pericanalicular lysosomes after vinblastine. These findings call attention to a possible role for hepatocyte microtubules in modulating the biliary excretion of endogenous (i.e. lysosomal enzymes) and exogenous (i.e., Triton WR-1339) constituents of hepatocyte lysosomes.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume9
Issue number1
StatePublished - 1984

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Microtubules
Colchicine
Lysosomes
Hepatocytes
Vinblastine
Liver
Enzymes
Bile
Bile Canaliculi
Hepatobiliary Elimination
Detergents
Fistula
Electron Microscopy
Electrons

ASJC Scopus subject areas

  • Physiology
  • Gastroenterology

Cite this

Microtubule modulation of biliary excretion of endogenous and exogenous hepatic lysosomal constituents. / Sewell, R. B.; Barham, S. S.; Zinsmeister, A. R.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 9, No. 1, 1984.

Research output: Contribution to journalArticle

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