title: Hormonally sensitive cyclic AMP phosphodiesterase in liver cells. An ecto-enzyme.
abstract: Ecto-cyclic AMP phosphodiesterase activity was determined from freshly isolated and cultured liver cells. The cells were capable of hydrolyzing cyclic AMP in the medium. The ecto-phosphodiesterase represents a low Km phosphodiesterase which was activated by physiological concentrations of insulin. The product, 5'-AMP, was recovered in the medium and not with the cells. The enzyme was inhibited with aminophylline and trypsin. The ecto-phosphodiesterase activity was proportional to cell number, and total phosphodiesterase activity increased 5- to 10-fold when the cells were ruptured. About one-third of the ecto-phosphodiesterase activity from freshly isolated liver was due to phosphodiesterase in the medium. No phosphodiesterase was in the medium of cultured liver cells.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008647:Mesocricetus; D051381:Rats; D014316:Tritium; D014357:Trypsin / Q000494:pharmacology
chemical_list: D007328:Insulin; D014316:Tritium; D000249:Adenosine Monophosphate; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D014357:Trypsin