Studies on responsiveness of hepatoma cells to catecholamines. IV. Lack of adrenergic activation of phosphorylase in rat ascites hepatoma cells.
Glycogen phosphorylase a activity in 7 rat ascites hepatoma cell lines treated with adrenergic agents, phenylephrine, epinephrine and isoproterenol, was investigated as compared with that in freshly isolated rat hepatocytes. Basal phosphorylase activities in hepatoma cells except AH7974 cells were lower than that in hepatocytes. Phosphorylase in hepatoma cells was not activated by any of the agents, while the enzyme activity in hepatocytes was clearly increased in a dose- and time-dependent manner. Phosphorylase in hepatocytes was sensitive to glucagon, but it was found to be insensitive to glucagon in all hepatoma cells. The present results suggest that rat ascites hepatoma cells may escape the glycogenolytic regulation by catecholamines and glucagon.
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D005934:Glucagon / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D010656:Phenylephrine / Q000494:pharmacology; D010762:Phosphorylase a / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D051381:Rats; D013566:Sympathomimetics / Q000494:pharmacology*
D013566:Sympathomimetics; D010656:Phenylephrine; D005934:Glucagon; D010762:Phosphorylase a; D006005:Phosphorylases; D007545:Isoproterenol; D004837:Epinephrine