Effects of Acetaldehyde on Hepatocyte Glycerol Uptake and Cell Size: Implication of Aquaporin 9

James J. Potter, Ayman Koteish, James Hamilton, Xiaopu Liu, Kun Liu, Peter Agre, Esteban Mezey

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The effects of ethanol and acetaldehyde on uptake of glycerol and on cell size of hepatocytes and a role Aquaporin 9 (AQP9), a glycerol transport channel, were evaluated. Methods: The studies were done in primary rat and mouse hepatocytes. The uptake of [ 14C] glycerol was determined with hepatocytes in suspension. For determination of cell size, rat hepatocytes on coated dishes were incubated with a lipophilic fluorochrome that is incorporated into the cell membrane and examined by confocal microscopy. A three-dimensional z scan of the cell was performed, and the middle slice of the z scan was used for area measurements. Results: Acute exposure to acetaldehyde, but not to ethanol, causes a rapid increase in the uptake of glycerol and an increase in hepatocyte size, which was inhibited by HgCl 2, an inhibitor of aquaporins. This was not observed in hepatocytes from AQP9 knockout mice, nor observed by direct application of acetaldehyde to AQP9 expressed in Xenopus Laevis oocytes. Prolonged 24-hour exposure to either acetaldehyde or ethanol did not result in an increase in glycerol uptake by rat hepatocytes. Acetaldehyde decreased AQP9 mRNA and AQP9 protein, while ethanol decreased AQP9 mRNA but not AQP9 protein. Ethanol, but not acetaldehyde, increased the activities of glycerol kinase and phosphoenolpyruvate carboxykinase. Conclusions: The acute effects of acetaldehyde, while mediated by AQP9, are probably influenced by binding of acetaldehyde to hepatocyte membranes and changes in cell permeability. The effects of ethanol in enhancing glucose kinase, and phosphoenolpyruvate carboxykinase leading to increased formation of glycerol-3-phosphate most likely contribute to alcoholic fatty liver.

Original languageEnglish (US)
Pages (from-to)939-945
Number of pages7
JournalAlcoholism: Clinical and Experimental Research
Volume35
Issue number5
DOIs
StatePublished - May 2011

Keywords

  • Acetaldehyde
  • Aquaporin 9
  • Cell size
  • Ethanol
  • Glycerol

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Toxicology
  • Psychiatry and Mental health

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