Differences of adenylate cyclase localization in guinea-pig peritoneal macrophages under different physiological conditions: an ultracytochemical study.

The ultrastructural localization of adenylate cyclase activity has been investigated in unfixed guinea-pig peritoneal macrophages in different physiological states (such as suspension, adhesion and phagocytosis) using a medium containing 5'-adenylyl-imidodiphosphate (AMP-PNP) as the substrate. Adenylate cyclase activity was observed in cytoplasmic vacuoles of macrophages in suspension; in the perinuclear space, endoplasmic reticulum, Golgi complex and pseudopods of adherent macrophages; and surrounding phagocytosed polystyrene particles. The activity was inhibited by Alloxan added to the incubation medium and no staining was observed when AMP-PNP was omitted from the medium. The segregation of this enzyme to phagocytic vacuoles and pseudopods may have significant implications in understanding cyclic nucleotide function in adhesion and phagocytosis.