13C NMR study of hepatic pyruvate carboxylase activity in tumor rats.

Abstract

Alanine and lactate, as major gluconeogenic substrates, must be converted into oxaloacetate by way of pyruvate carboxylase before their entry into gluconeogenesis. Although it is well known that hepatic gluconeogenesis from these substrates is increased in tumor hosts, the involvement of pyruvate carboxylase has not been demonstrated. In the present study, we examined pyruvate carboxylase activity in the perfused livers of tumor rats using 13C NMR spectroscopy with [3-13C]-alanine as the gluconeogenic substrate. A substantial increase in hepatic [3-13C]-aspartate production was found in the tumor rats. Since aspartate accumulation directly reflects fluxes of alanine through pyruvate carboxylase, the observed increase in hepatic production of [3-13C]-aspartate in tumor rats indicates that pyruvate carboxylase activity is significantly enhanced.

• Authors: K J Liu, R Kleps, T Henderson, L Nyhus
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 179 Issue 1 Pg. 366-71 (Aug 30 1991) ISSN: 0006-291X [Print] United States
• PMID: 1883366 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Carbon Isotopes
• Pyruvate Carboxylase
• Alanine

Topics

• Alanine (metabolism)
• Animals
• Carbon Isotopes
• Citric Acid Cycle
• Female
• Liver (enzymology)
• Magnetic Resonance Spectroscopy (methods)
• Mammary Neoplasms, Experimental (enzymology)
• Models, Biological
• Pyruvate Carboxylase (metabolism)
• Rats
• Rats, Inbred F344
• Reference Values