[Glutamine and the liver cell: metabolism, properties and the concept of metabolic regulation by cell swelling]

Abstract

Glutamine is transported into the hepatocyte in a sodium-dependent manner. A consequence of the sodium-dependent entry of glutamine is an osmotic swelling of the cell. In the past, glutamine has been given a number of anabolic properties such as the stimulation of both glycogen and lipid synthesis from glucose. The mechanism through which glutamine activates key enzymes in these metabolic pathways involves the glutamine-induced cell swelling. Moreover, glutamine regulates gene expression of the beta-actin gene at a transcriptional level as well as that of the phosphoenolpyruvate carboxykinase gene by stabilizing its mRNA. Regulation of gene expression by glutamine also involves the cell swelling phenomena. Cell swelling is now regarded as a novel regulatory element of hepatic metabolism.