Comparative biochemical, histochemical and autoradiographic studies of Na+/k+-ATPase in the rectum of dragonfly larvae (Odonata, Aeshnidae).

Na+/K+-ATPase localization in the rectal wall of larval Aeshna cyanea (Insecta, Odonata) was studied with histochemical precipitation techniques and 3H-ouabain autoradiography in conjunction with biochemical measurements of enzyme activities and radiospectrometry of 3H-ouabain binding, respectively. The NPP-strontium and ATP-lead methods led to complete inhibition of Na+/K+-ATPase in this organ and hence to unreliable histochemical results. The 3H-ouabain binding technique revealed sodium pump sites at the basolateral plasma membranes of the absorptive rectal chloride epithelia.