DIFFERENTIAL ENZYMATIC BEHAVIOUR OF SINGLE PROXIMAL SEGMENTS OF SUPERFICIAL AND JUXTAMEDULLARY NEPHRON .I. ALKALINE PHOSPHATASE, (MG++) ATPASE AND (NA+K+) ATPASE

With three phosphohydrolases, i. e. alkaline phosphatase (Na+K+), ATPase and (Mg++) ATPase, a segmentation of the proximal tubule and a marked difference between the short (superficial) and long (Juxtamedullary) nephron is revealed by quantitative histochemistry. With the exception of the superficial nephron of the male rat, alkaline phosphatase activity increases along the proximal tubule independent of sex. (Na+K+) ATPase and (Mg++) ATPase show in both types of nephrons a decrease of activity along the proximal tubule. The juxtamedullary nephron is more active than the superficial. Parallelism of the site of avtivity for alkaline phosphatase and the location of reabsorption of phosphate ions is discussed. Morphological and physiological data from the literature are brought into connexion with the enzymatic changes of a (Na+K+) ATPase activity decrease. © 1969 Springer-Verlag.