IMMUNOCYTOCHEMICAL STUDIES OF MAJOR GAP JUNCTION PROTEINS IN RAT SALIVARY-GLANDS

We examined protein components of the gap junctions between acinar cel ls of the parotid, sublingual and submandibular glands of the rat, usi ng type-specific antibodies directed against major gap junction protei ns, connexin32 (Cx32) and connexin26 (Cx26). Double-immunofluorescence microscopy revealed that fluorescent spots of both connexins in the p arotid and sublingual glands were distributed between the apposed regi ons of acinar cells. They appeared together, or were co-localized. The intensity of the Cx26-associated fluorescent signals was relatively w eak in the submandibular glands compared with the other glands and was absent from some acini. When present, these spots were always co-loca lized with Cx32 immunoreactive positive spots. The results suggest tha t Cx32 and Cx26 in rat salivary glands are co-localized within the sam e gap junctional plaques when simultaneously expressed by the same aci nar cells.