Localization of Connexin 26, 32 and 43 in Rat Parotid Glands

We investigated the distribution and localization of connexin 26, 32, and 43 in rat parotid glands. Immunofluorescence microscopy revealed the presence of spots reacting for connexin 26 and 32 between endpiece cells. A few spots indicating connexin 43 occasionally were observed in the parotid glands. Connexin 43-positive spots were localized around intercalated ducts. No positive spots for these connexins were detected between ductal cells. Double immunofluorescence microscopy revealed that connexin 26-reactive sites could be observed within the same spots as connexin 32. Double immuno-electron microscopy confirmed that connexin 26 and 32 were co-localized in the same gap junction. These results suggest that connexin 26 and 32 are associated with secretory function and permeability between endpiece cells and that connexin 43 is associated with contraction of the myoepithelial cells that surround intercalated ducts in the rat parotid glands.