A histochemical localization of acetylcholinesterase and cholinesterase activities in mammalian kidneys.

An acetylcholinesterase (AChE) activity and a cholinesterase (ChE) activity were localized in mammalian kidneys, using a modified histochemical method of Koelle. The animals studied were mouse, hamster, cat, rat, and guinea pig. The kidneys were excised after in situ perfusion and fixation to eliminate AChE and ChE activities of blood. We carried out a relatively long incubation (up to 4 h) to detect weak AChE and ChE activities in the tissue. The differences in enzymatic activities in the kidneys from these 5 animals were important. The AChE activity was localized in the glomerulus (mouse, hamster, cat, and rat) and in the tubule (mouse, hamster, and rat). The ChE activity was also localized in the glomerulus (mouse and rat) and in the tubule (mouse and cat). An important nonspecific esterase activity was observed in the tubules of rat, guinea pig, and cat. In the thin segment of the loop of Henle, except of cat kidney, no esterase activity at all was observed. Electron microscopy revealed that, in the mouse kidney, both AChE and ChE activities were localized in the endoplasmic reticulum of glomerular endothelial cells and mesangial cells. (An AChE activity was localized mainly in mesangial cells, while ChE activity was localized mainly in endothelial cells). AChE and ChE activities were also localized in the endoplasmic reticulum of tubule cells.