Light microscopic visualization of transport ATPase in the chick kidney and intestine using catalytic histochemistry

To visualize the enzyme Na+/K(+)-ATPase (transport ATPase) in the chick kidney and intestine two recent methods of catalytic histochemistry were modified using capture of inorganic phosphate with lead according to Mayahara et al.(1980) or cerium after Kobayashi et al. (1987). For light microscopy a new step for the visualization of the reaction product was added; lead phosphate was visualized with (NH4)2S and cerium phosphate with the DAB-H2O2-Ni-hexamonium sulfate method. Reaction product was specifically found in the basolateral plasma membrane region of enterocytes and renal epithelial cells (distal tubules, thick ascending limbs of Henle's loops, cortical collecting ducts). Treatment of the sections with 8 mM levamisole and 40 mM L-phenylalanine before and during incubation was necessary to suppress the co-reaction of non-specific alkaline phosphatase in the microvillous zone of proximal tubules and enterocytes. The reaction specificity was controlled with 10 mM ouabain which completely inhibited the basolateral activity in enterocytes and renal epithelial cells. The described methods for transport ATPase are reliable and provide reproducible results in the chick.