Ultracytochemical localization of guanylate cyclase activity in guinea-pig peritoneal macrophages under different physiological conditions.

Guanylate cyclase activity was investigated in guinea-pig peritoneal macrophages under different physiological conditions (such as adhesion and phagocytosis) with an ultracytochemical method using guanylyl-imidodiphosphate as a substrate. The enzyme was detected on the perinuclear envelope, endoplasmic reticulum, Golgi complex and mitochondria of adherent and phagocytozing macrophages. No reaction product was present around phagocytozed polystyrene particles. The amount of final reaction product was increased by the addition of sodium azide to the incubation medium and no staining was observed when the substrate was omitted from the medium.