Electrolyte transport in the mouse trachea: no evidence for a contribution of luminal K(+) conductance
| Autor: | Rainer Schreiber, B. Mürle, Jane Sun, Karl Kunzelmann |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
medicine.medical_specialty
BK channel IBMX Potassium Channels Charybdotoxin Physiology Biophysics Biology Apamin Sensitivity and Specificity Membrane Potentials chemistry.chemical_compound Mice Chlorides Internal medicine medicine Potassium Channel Blockers Animals Cells Cultured Forskolin Electric Conductivity Potassium channel blocker Epithelial Cells Cell Biology respiratory system Apical membrane Trachea Endocrinology chemistry biology.protein Cotransporter medicine.drug |
| Zdroj: | The Journal of membrane biology. 189(2) |
| ISSN: | 0022-2631 |
| Popis: | Recent studies on frog skin acini have challenged the question whether Cl(-) secretion or Na(+) absorption in the airways is driven by luminal K(+) channels in series to a basolateral K(+) conductance. We examined the possible role of luminal K(+) channels in electrolyte transport in mouse trachea in Ussing-chamber experiments. Tracheas of both normal and CFTR (-/-) mice showed a dominant amiloride-sensitive Na+ absorption under both, control conditions and after cAMP-dependent stimulation. The lumen-negative transepithelial voltage was enhanced after application of IBMX and forskolin and Cl(-) secretion was activated. Electrolyte secretion induced by IBMX and forskolin was inhibited by luminal glibenclamide and the blocker of basolateral Na(+2)Cl(-)K(+) cotransporter azosemide. Similarly, the compound 293B, a blocker of basolateral KCNQ1/KCNE3 K(+) channels effectively blocked Cl(-) secretion when applied to either the luminal or basolateral side of the epithelium. RT-PCR analysis suggested expression of additional K(+) channels in tracheal epithelial cells such as Slo1 and Kir6.2. However, we did not detect any functional evidence for expression of luminal K(+) channels in mouse airways, using luminal 293B, clotrimazole and Ba(2+) or different K(+) channel toxins such as charybdotoxin, apamin and a-dendrotoxin. Thus, the present study demonstrates Cl(-) secretion in mouse airways, which depends on basolateral Na(+2)Cl(-)K(+) cotransport and luminal CFTR and non-CFTR Cl(-) channels. Cl(-) secretion is maintained by the activity of basolateral K(+) channels, while no clear evidence was found for the presence of a luminal K(+) conductance. |
| Databáze: | OpenAIRE |
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