UNIFORM DISTRIBUTION AND CONCENTRATION OF AMINOPEPTIDASE IN PROXIMAL TUBULES OF PIG KIDNEY

Abstract

The concentration of aminopeptidase in cross-sections in proximal tubules of pig kidney was investigated with a specific fluorescent antibody technique and a specific histochemical technique. The concentration was found to be independent of the diameter of the tubule and of the depth of the cortex. Four-micron segments of proximal tubules contained approximately l0⁴ molecules of aminopeptidase/µ², which is adequate for a rapid hydrolysis of peptides, even in very small concentrations, such as angiotensin II at 10 ⁵ of the physiologic serum concentration. The findings suggest that with regard to this enzyme all sections of the proximal tubule function equivalently.