title: Effect of inhibitors and diuretics on electrical potential differences in rat kidney proximal tubule.
abstract: Active transport potentials were studied across early loops of rat proximal tubule during luminal perfusion and peritubular superfusion with HCO3- Ringer's solution of identical ionic composition. From the effects of the carbonic anhydrase inhibitor acetazolamide and of ouabain it is concluded 1. that the lumen-positive active transport potential indicates an excess of active H+ secretion/HCO3- absorption over active Na+ absorption and 2. that the lumen-negative active transport potential, which develops in the presence of glucose (and/or aminoacids) in the tubular lumen, indicates stimulation of active Na+ absorption. Ouabain did not abolish the lumen-positive potential difference suggesting that active H+/HCO3- transport and active Na+ transport may be to some extent independent. Among the diuretics tested the mercurial diuretic mersalyl acted primarily on Na+ transport, and furosemide acted on HCO3- transport, whereas the effect of ethacrynic acid appeared to be unspecific.
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001693:Biological Transport, Active; D004232:Diuretics / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000502:physiology; D008564:Membrane Potentials; D010042:Ouabain / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D004232:Diuretics; D010042:Ouabain; D006859:Hydrogen; D012964:Sodium; D010695:Phlorhizin; D005947:Glucose