Effect of ADH on rubidium transport in isolated perfused rat cortical collecting tubules.
Unidirectional fluxes of 86Rb+ were measured as an indicator of potassium transport in isolated rat cortical collecting tubules perfused and bathed at 38 degrees C with isotonic solutions in which Rb+ replaced K+. Under control conditions the lumen-to-bath flux (Jl----b) was significantly less than the bath-to-lumen flux (Jb----l), indicating net Rb+ secretion. Net secretion increased approximately 180% after addition of 100 microU/ml of arginine vasopressin (ADH) to the bathing solution, due to a rapid and reversible increase in Jb----l from 4.6 +/- 0.8 to 9.0 +/- 1.9 pmol X min-1 X mm-1 with no significant change in Jl----b. The ADH effect was completely inhibited by 2 mM luminal Ba2+. The average transepithelial voltage (Ve) was not significantly different from zero in the control period but became lumen negative (-5 to -10 mV) after ADH. With 10(-5) M amiloride in the lumen Ve was lumen positive (+2 to +4 mV) and was unaltered by ADH or Ba2+, yet ADH produced a significant but attentuated increase in Jb----l with no change in Jl----b. The results indicate that ADH augments net K+ secretion either by an increase in the Ba2+-sensitive conductance of the apical membrane or by an increase in the electrochemical potential driving force for net Rb+ secretion through this pathway.
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D066298:In Vitro Techniques; D007672:Kidney Cortex; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D011868:Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D012413:Rubidium / Q000378:metabolism*
D011868:Radioisotopes; D001127:Arginine Vasopressin; D001464:Barium; D000584:Amiloride; D012413:Rubidium