Localization of a renal kallikrein immunoreactive-like substance in rat ureter

An antibody against rat kallikrein was produced in rabbits and its localization was studied in various organs of the rat to confirm its specificity. The distribution of immunoreactive kallikrein was studied in rat ureter by use of immunochemical techniques. Ureteral tissue was fixed in Zamboni's-glutaraldehyde fixative and immunostained with indirect immunofluorescence and the peroxidase-antiperoxidase (PAP) method for light and electron microscopy. Preabsorption of the primary polyclonal antiserum with purified rat urinary kallikrein and substitution with normal serum were used as controls. By light microscopy, kallikrein was localized in the lamina propria and in the adventitial connective tissue surrounding the entire ureter. Immunoelectron microscopy confirmed this immunolocalization. Immunoreactive kallikrein was concentrated in fibroblasts of connective tissue and was not present in collagen fibers. Immunoreactivity was associated with the Golgi complex, free polyribosomes, and rough endoplasmic reticulum. No immunostaining was observed in other subcellular components of fibroblasts.