title: Plasma membrane localization and metabolism of alkaline phosphodiesterase I in mouse peritoneal macrophages.
abstract: Alkaline phosphodiesterase I activity is demonstrable in lysates of mouse resident peritoneal macrophages (1.43 mU/mg), endotoxin-stimulated macrophages (1.36 mU/mg), and thioglycollate-stimulated macrophages (3.91 mU/mg), as well as in the lysates of several mouse cell lines. The enzyme showed little variation in culture, although serum deprivation caused a 50% decrease in enzyme activity. In each of the three macrophage types about 80% of the enzyme is inactivated by the diazonium salt of sulfanilic acid, indicating that this enzyme is a component of the plasma membrane. In thioglycollate-stimulated cells about the same fraction of enzyme can be inactivated with papain corroborating this assignment. The enzyme is inactivated with a half-time of 14.1 h in resident cells, but this is decreased to 8.2 h in endotoxin cells, and to 5.7 h in thioglycollate cells. These results are consistent with the hypothesis that the endogenous pinocytic rate is a major determinant of plasma membrane turnover. In addition, the different synthetic rates measured in resident and inflammatory cells support the concept that macrophage activation is a differentiative process leading to a qualitatively new cell type.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003979:Diazonium Compounds / Q000494:pharmacology; D005260:Female; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D010206:Papain / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D013425:Sulfanilic Acids / Q000494:pharmacology; D013864:Thioglycolates / Q000494:pharmacology
chemical_list: D003979:Diazonium Compounds; D010726:Phosphodiesterase Inhibitors; D013425:Sulfanilic Acids; D013864:Thioglycolates; D003513:Cycloheximide; D010727:Phosphoric Diester Hydrolases; D010206:Papain