The mechanism of action of hydration state was studied on β-actin gene expression in isolated hepatocytes. Results obtained with Northern blot analysis and run on transcription assays show that hypoosmolarity increased and hyperosmolarity decreased the β-actin mRNA level through a corresponding modulation of the rate of the gene transcription. Glutamine, which is known to induce cell swelling, also increased the β-actin mRNA level in a dose-dependent manner and induced a stimulation of the β-actin gene transcription. Thus, cell hydration state regulates gene expression in the liver through a transcriptional mechanism.
