Tissue distribution of an inducible cystatin in isoproterenol-treated rats

A well-characterized, monospecific rabbit antiserum directed to an isoproterenol-inducible type 2 salivary cystatin was used for immunocytochemical localization of this cystatin in rat salivary glands, as well as in other organs of normal and isoproterenol-treated rats. Immunocytochemical analysis revealed a moderate staining of secretory granules within the acinar cells of submandibular glands, which was more pronounced in tissues obtained from female rats. In addition, the inducible cystatin was readily detected within granular convoluted tubule cells and striated duct cells of submandibular glands of both male and female rats, although not all such structures were stained. Cystatin was also localized in the proximal convoluted tubule cells of the kidney in isoproterenol-treated female rats. Western blotting and Ouchterlony double diffusion analysis showed that the cystatin from submandibular gland and kidney extracts was immunologically identical.