Ultracytochemical localization of Ca2+-ATPase activity on the epithelial cells of rat trachea.

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Abstract
A new 1 step method for light microscopic and EM localization of Ca2+-ATPase activity was applied to the rat trachea. Under light microscopic examination, Ca2+-ATPase reaction was found on the luminal side of the tracheal epithelium and on the nerve fibers of the submucosa. On EM examination, the most intense Ca2+-ATPase reaction was observed on the ciliated cells in the tracheal epithelium. Cytochemical reaction products were observed in the axoneme, probably corresponding to the bridge-like structures between the axoneme and ciliary membrane, the outer and inner arms of doublets, the radial spoke heads, the central sheath, the central core bridge and the outer surface of the ciliary membrane. Enzyme activities were also found on the peripheral structures of triplets, which may correspond to connectors, and fibrous elements of the rootlet bundle. The reaction completely disappeared when Ca2+ or ATP was removed from the incubation medium. Substrate specificity was observed by substituting NPP [nucleoside diphosphate] or GMP for ATP in the incubation medium. Pb and Pi were identified in the reaction product by X-ray microanalysis with an analytical EM, suggesting that the reaction products were PbPO4. Ca2+-ATPase reaction was also observed on the microvilli, lateral plasma membrane and cytoplasmic projections in ciliated and nonciliated cells such as brush cells, secretory cells, intermediate cells and basal cells. Ca2+-ATPase activities, apparently related to ciliary movement and Ca2+-transport, were clearly localized in the rat trachea.