Membrane potential in isolated epithelial cells of the endolymphatic sac in the guinea-pig.
The membrane potential (Em) in epithelial cells isolated from the intermediate portion of the endolymphatic sac (ES) of the guinea-pig was recorded using the whole-cell patch-clamp technique. In the steady state the Em was -53.5+/-1.5 mV (n = 74), which is similar to that in epithelial cells of other tissues. Application of 1 MM ouabain induced a depolarization of Em by approximately 10 mV (n = 6), suggesting that an active ion transport process by Na+-K+-ATPase may be present in the ES epithelial membrane. Increasing extracellular K+ concentrations from 5 to 100 mM induced a significant membrane depolarization that was close to the K+ equilibrium potential calculated by the Nernst equation, indicating that K+ may be a predominant permeable ion in the ES epithelial membrane. Total replacement of extracellular Na+ with NMDG+ led to a significant membrane hyperpolarization of 38.7+/-2.5 mV (n = 18), suggesting that Na+ may be another major permeable ion for the ES epithelial membrane. Reducing extracellular Cl- concentrations from 149.3 to 7 mM had no significant effect on Em, indicating that Cl- may be a negligible permeable ion in the ES epithelial membrane.
Mori
N
N
Department of Otolaryngology, Kagawa Medical University, Japan.
Wu
D
D
Furuta
H
H
D000818:Animals; D002712:Chlorides / Q000502:physiology; D004712:Endolymphatic Sac / Q000187:drug effects / Q000502:physiology*; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005942:Gluconates / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008536:Meglumine / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology; D012964:Sodium / Q000502:physiology
D002712:Chlorides; D005942:Gluconates; D010042:Ouabain; D008536:Meglumine; D012964:Sodium; C030691:gluconic acid; D011188:Potassium