Inactivation of phosphofructokinase in chicken hepatocytes by epinephrine.
The effects of epinephrine on phosphofructokinase activity in hepatocytes from fed chickens were studied in crude extracts and after partial purification. The mechanism of epinephrine action was elucidated by use of phentolamine and penbutulol. Phosphofructokinase activity was decreased in extracts of cells exposed to epinephrine when measured at sub-saturating as well as saturating concentrations of fructose 6-phosphate. This effect was still present after filtration through Sephadex G25 gel and a subsequent precipitation with ammonium sulfate. Half-maximal effects of epinephrine were found in a concentration range between 10(-8) and 10(-7) M epinephrine. The effect of epinephrine was unaffected by Ca2+ or the alpha-adrenergic antagonist phentolamine, and was abolished by the beta-adrenergic antagonist penbutulol. We assume that the effects of epinephrine on the activity of chicken liver phosphofructokinase are mediated by a cAMP-dependent mechanism which cannot be explained by concentration shifts of low-molecular-mass substances such as fructose 2,6-bisphosphate.
D000818:Animals; D002645:Chickens; D004837:Epinephrine / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis; D008099:Liver / Q000201:enzymology*; D008297:Male; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors*
D007527:Isoenzymes; D005934:Glucagon; D010732:Phosphofructokinase-1; D004837:Epinephrine