H-K-ATPase enhancement of Rb efflux by cortical collecting duct

Xiaoming Zhou, Charles S. Wingo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Previous studies suggest that enhancement of rubidium tracer (86Rb) lumen-to-bath efflux following removal of luminal Na is mediated in part by a Ba-insensitive pathway. To determine the role of a primary active K pump in this response, we examined the action of known inhibitors of H-K-ATPase (Sch 28080) and Na-K-ATPase (ouabain) on the 86Rb lumen-to-bath efflux coefficient (KRb). Luminal Sch 28080 (10 μM) significantly reduced KRb by 39 ± 8.0% (P < 0.05), whereas luminal ouabain (0.1 mM) reduced KRb by 10 ± 14% (P = not significant), suggesting that a luminal H-K-ATPase mediates Rb efflux. To examine whether H-K-ATPase mediates the increase in KRb following removal of luminal Na, additional experiments were conducted to examine the effect of Sch 28080 on KRb in the presence and the absence of luminal Na. In the presence of luminal Na, 10 μM Sch 28080 reduced KRb by 15 ± 5.0%. However, in the absence of luminal Na, 10 μM Sch 28080 decreased KRb by 48 ± 8.2%. The percentage inhibition of KRb by Sch 28080 was significantly greater in the absence of luminal Na than in its presence (P < 0.01), suggesting that the enhancement of KRb following removal of luminal Na is mediated in part by an H-K-ATPase pathway. In either case transepithelial voltage was not significantly altered. In contrast to the lack of effect of luminal ouabain, addition of 0.1 mM ouabain to the bath increased KRb (69.8 ± 11.1 vs. 95.9 ± 18.7 nm/s, P < 0.05). However, this effect of ouabain on KRb was totally abolished by perfusion of the cortical collecting duct (CCD) in the presence of 10 μM luminal Sch 28080 (69.8 ± 14.0 nm/s, basal period; 69.6 ± 14.1 nm/s, ouabain period). These data are consistent with the following conclusions, at least during K restriction: 1) H-K-ATPase is responsible for Rb (K) absorption in the rabbit CCD, 2) the presence of luminal Na reduces Rb (K) absorption by an H-K-ATPase-mediated mechanism, and 3) basolateral ouabain addition stimulates Rb (K) absorption via H-K-ATPase.

Original languageEnglish
Pages (from-to)F43-F48
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Issue number1 32-1
StatePublished - Jul 1992


  • Acidification
  • Microperfusion
  • Potassium
  • Potassium absorption
  • Sch 28080
  • Sodium-potassium-adenosinetriphosphatase


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