Ultrastructural localization of alkaline phosphatase activity in the proximal convoluted tubule cells of the gerbil Meriones crassus using a cerium-based method.

Histochemical activity of alkaline phosphatase in the proximal convoluted tubule of the gerbil Meriones crassus has been detected. The reaction product was strongly marked at both the apical surface and the basal part of the cells comprising the basal infoldings with their extended tips and the profiles of the membrane-bound bodies that were easily recognisable by their rounded shape. The reaction product was in the form of fine, uniform deposits in response to cerium chloride as a capture agent. Other cytoplasmic structures did not display these deposits. In addition, the study provided the application of levamisole which caused remarkable reduction of the enzyme activity. Using lead nitrate as a capture agent, the sections showed dense coarse, irregular clusters nearly at the same sites. Control experiments, processed in the absence of the substrate sodium beta-glycerophosphate did not demonstrate the presence of any deposits. The present study, which demonstrates for the first time the presence of alkaline phosphatase activity in the proximal convoluted tubule cells of such desert rodents, does not consider the relationship of the enzyme localization and the basal components of the cells including the nature of the membrane-bound bodies which are still under investigation.