Effects of propylene glycol on redox state of the perfused rat liver — a note of caution

Summary

Propylene glycol is used as a solvent for bile salts in studies on their biologic effects on the liver. While using this solvent (32–64 mmol/l) in the isolated perfused rat liver, we found a significant change in the extramitochondrial redox system as indicated by a fivefold increase of the lactate pyruvate ratio in the perfusate. The increase was due to an increased uptake of pyruvate (0.8 µmol/g/min) and to a release of lactate (1.8 µmol/g/min). The intramitochondrial redox state was affected to a lesser degree as extimated by the β-hydroxybutyrate acetoacetate ratio (twofold increase). These abnormalities resemble those induced by similar concentrations of ethanol. We suggest, therefore, that investigators studying bile acids should be aware of this artifact which causes significant alterations in cellular energy systems and enzyme activities.