Transforming growth factor-beta 1 rapidly activates phosphorylase in a calcium-dependent manner in rat hepatocytes.
Transforming growth factor-beta 1 (TGF-beta 1) rapidly activated phosphorylase in isolated rat hepatocytes (half-maximal rate of activation with approximately 0.1 ng/ml). Removal of Ca2+ from the external medium just before TGF-beta 1 addition markedly attenuated phosphorylase activation. TGF-beta 1 (1 ng/ml) produced a small increase in [Ca2+]i (approximately 10% increase after 30 s), which appears sufficient to account for phosphorylase activation. These observations indicate that activation of the TGF-beta 1 signal transduction system in hepatocytes is linked with a small increase in [Ca2+]i, and external Ca2+ may contribute in part to this increase.
Hahm
S H
SH
Department of Pharmacology, University of South Carolina School of Medicine, Columbia 29208.
Cooper
R H
RH
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D010656:Phenylephrine / Q000494:pharmacology; D010762:Phosphorylase a / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D016212:Transforming Growth Factor beta; D010656:Phenylephrine; D010762:Phosphorylase a; D002118:Calcium