Acid hydrolases in the suckling rat small intestine. II. On the importance of alkaline phosphatase inhibition in the histochemical localization of acid phosphatase activity

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Abstract
Synopsis Phosphatase activities against β-glycerophosphate,i-naphthyl phosphate and naphthol AS-TR phosphate were investigated, at acid and alkaline pH levels, using unfixed and fixed cryostat sections of suckling rat jejunum. The use ofiomm EDTA andiomm NaF as inhibitors indicated that alkaline phosphatase is predominantly located in the microvillous region of the absorptive cells, while acid phosphatase is located in small particles distributed between the brush borders and the nuclei of these cells. Alkaline phosphatase activity was found to interfere with the localization of acid phosphatase unless EDTA was included in the incubation medium. A modified Gomori medium, containingiomm EDTA and additional lead nitrate, is descrbed. Latency experiments using this medium, with unfixed sections, indicated the lysosomal nature of particulate acid phosphatase. The discussion stresses the importance of including an alkaline phosphatase inhibitor in incubation media designed to localize extralysosomal acid phosphatase activity.