Basolateral Na+/H+ exchange maintains potassium secretion during diminished sodium transport in the rabbit cortical collecting duct
| Autor: | Shuichi Tsuruoka, Akio Fujimura, Eiji Kusano, Shigeaki Muto, Donald W. Seldin, Yukio Miyata, Wen-Hui Wang, Gerhard Giebisch |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
medicine.medical_specialty
BK channel ATPase Potassium Sodium chemistry.chemical_element Membrane Potentials Internal medicine principal cell medicine Animals Kidney Tubules Collecting in vitro microperfusion ROMK Epithelial polarity basolateral Na+-K+-ATPase Membrane potential biology Chemistry Biological Transport Ca2+-activated big-conductance K+ channels K+ transport Apical membrane Endocrinology Nephrology biology.protein Biophysics Rabbits Sodium-Potassium-Exchanging ATPase |
| Zdroj: | Kidney International. 75:25-30 |
| ISSN: | 0085-2538 |
| DOI: | 10.1038/ki.2008.447 |
| Popis: | Stimulation of the basolateral Na(+)/K(+)-ATPase in the isolated perfused rabbit cortical collecting duct by raising either bath potassium or lumen sodium increases potassium secretion, sodium absorption and their apical conductances. Here we determined the effect of stimulating Na(+)/K(+)-ATPase on potassium secretion without luminal sodium transport. Acutely raising bath potassium concentrations from 2.5 to 8.5 mM, without luminal sodium, depolarized the basolateral membrane and transepithelial voltages while increasing the transepithelial, basolateral and apical membrane conductances of principal cells. Fractional apical membrane resistance and cell pH were elevated. Net potassium secretion was maintained albeit diminished and was still enhanced by raising bath potassium, but was reduced by basolateral ethylisopropylamiloride, an inhibitor of Na(+)/H(+) exchange. Luminal iberitoxin, a specific inhibitor of the calcium-activated big-conductance potassium (BK) channel, impaired potassium secretion both in the presence and absence of luminal sodium. In contrast, iberitoxin did not affect luminal sodium transport. We conclude that basolateral Na(+)/H(+) exchange in the cortical collecting duct plays an important role in maintaining potassium secretion during compromised sodium supplies and that BK channels contribute to potassium secretion. |
| Databáze: | OpenAIRE |
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