Localization of carbonic anhydrase in the salivary glands of the cockroach, Periplaneta americana.

Carbonic anhydrase (CA) activity was localized in the salivery glands of the cockroach, Periplaneta americana, by (1) Hansson's histochemical technique, and (2) the use of the fluorescent sulphonamide, 5-dimethyl-amino-naphthalene-1-sulphonamide (DNSA). Both techniques reveal the same distribution pattern of CA in the four morphologically different cell types of the glands: peripheral cells, central cells, inner acinar duct cells, and distal duct cells. Positive reactions with Hansson's cobalt/phosphate technique were found in the apical regions of the peripheral cells and the distal duct cells, and were inhibited by 10(-5) M acetazolamide in control experiments. No staining could be detected in the central cells and the inner acinar duct cells. The fluorescent CA inhibitor DNSA (10(-4)M) specifically stained the peripheral cells and the distal duct cells in methanol-fixed cryostat sections, whereas the central cells and the inner acinar duct cells remained unstained. The role of CA in the peripheral cells is not clear. CA activity in the distal duct cells may provide the protons needed to run the vacuolar-type H(+)-ATPase on the apical infoldings of the cells. This ATPase may be involved in modification of the primary saliva.