Abstract
When isolated livers from starved rats are perfused with lactate at constant perfusate pH and P(co(2)), there is a marked gradient of cell pH (pH(i)) along the length of the lobular radius, with periportal cells being substantially more alkaline than perivenous cells. In the present studies, the perivenous 21% of the lobular volume was destroyed by retrograde digitonin perfusion, and antegrade perfusion restored. pH(i) was determined by (31)P-NMR. The remaining periportal cells, the site of gluconeogenesis from lactate, had a substantially higher mean pH(i) (7.42) than did the intact liver (7.23). When lactate was removed from the perfusate, mean pH(i) decreased to 7.25. The corresponding concentration of cell bicarbonate fell with a half-time of approximately 5 min. When lactate was re-introduced mean pH(i) rose to 7.34. We conclude that a major contributor to periportal alkalinity under these conditions is proton consumption during gluconeogenesis from lactate ions.
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Selected References
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- Burns S. P., Cohen R. D., Iles R. A., Bailey R. A., Desai M., Germain J. P., Going T. C. Zonation of gluconeogenesis, ketogenesis and intracellular pH in livers from normal and diabetic ketoacidotic rats: evidence for intralobular redistribution of metabolic events in ketoacidosis. Biochem J. 1999 Oct 1;343(Pt 1):273–280. [PMC free article] [PubMed] [Google Scholar]
- Burns S. P., Cohen R. D., Iles R. A., Germain J. P., Going T. C., Evans S. J., Royston P. A method for determination in situ of variations within the hepatic lobule of hepatocyte function and metabolite concentrations. Biochem J. 1996 Oct 15;319(Pt 2):377–383. doi: 10.1042/bj3190377. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Burns S. P., Desai M., Cohen R. D., Hales C. N., Iles R. A., Germain J. P., Going T. C., Bailey R. A. Gluconeogenesis, glucose handling, and structural changes in livers of the adult offspring of rats partially deprived of protein during pregnancy and lactation. J Clin Invest. 1997 Oct 1;100(7):1768–1774. doi: 10.1172/JCI119703. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Burns S. P., Murphy H. C., Iles R. A., Bailey R. A., Cohen R. D. Hepatic intralobular mapping of fructose metabolism in the rat liver. Biochem J. 2000 Jul 15;349(Pt 2):539–545. doi: 10.1042/0264-6021:3490539. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cohen R. D., Henderson R. M., Iles R. A., Monson J. P., Smith J. A. The techniques and uses of intracellular pH measurements. Ciba Found Symp. 1982;87:20–35. doi: 10.1002/9780470720691.ch2. [DOI] [PubMed] [Google Scholar]
- Cohen R. D., Iles R. A., Barnett D., Howell M. E., Strunin J. The effect of changes in lactate uptake on the intracellular pH of the perfused rat liver. Clin Sci. 1971 Aug;41(2):159–170. doi: 10.1042/cs0410159. [DOI] [PubMed] [Google Scholar]
- Fafournoux P., Demigné C., Rémésy C. Carrier-mediated uptake of lactate in rat hepatocytes. Effects of pH and possible mechanisms for L-lactate transport. J Biol Chem. 1985 Jan 10;260(1):292–299. [PubMed] [Google Scholar]
- Fitz J. G., Lidofsky S. D., Xie M. H., Cochran M., Scharschmidt B. F. Plasma membrane H(+)-HCO3- transport in rat hepatocytes: a principal role for Na(+)-coupled HCO3- transport. Am J Physiol. 1991 Nov;261(5 Pt 1):G803–G809. doi: 10.1152/ajpgi.1991.261.5.G803. [DOI] [PubMed] [Google Scholar]
- Monson J. P., Smith J. A., Cohen R. D., Iles R. A. Evidence for a lactate transporter in the plasma membrane of the rat hepatocyte. Clin Sci (Lond) 1982 Apr;62(4):411–420. doi: 10.1042/cs0620411. [DOI] [PubMed] [Google Scholar]