Cell volume control in vestibular dark cells during and after a hyposmotic challenge.
Cell height was measured as an index of volume in a preparation of vestibular dark cells in which the perfusate had access to both sides of the epithelium. In response to a hyposmotic challenge induced by removal of 75 mM NaCl, cell height increased to 107%; however, cell width did not increase. Significantly larger increases in cell height were observed in the absence of Cl- or K+ or in the presence of ouabain, lidocaine, barium, or quinidine, at 7 degrees C, or after fixation with glutaraldehyde. However, no significantly different swelling was observed during a hyposmotic challenge in the absence of Na+ or in the presence of bumetanide or ethoxyzolamide. Subsequent return to control osmolarity caused a regulatory volume increase that was dependent on Na+, Cl-, and K+, inhibited by bumetanide, ouabain, or 7 degrees C, however not inhibited by ethoxyzolamide, barium, quinidine, or lidocaine. The data suggest that cell volume control during the hyposmotic challenge involved a mechanism dependent on cytosolic KCl and the Na(+)-K(+)-ATPase and that the Na(+)-Cl(-)-K+ cotransporter was involved in regulatory volume increase.
Wangemann
P
P
Cell Physiology Laboratory, Boys Town National Research Hospital, Omaha, Nebraska 68131.
Shiga
N
N
D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors; D005849:Gerbillinae; D008353:Mannitol / Q000494:pharmacology*; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D026902:Potassium Channel Blockers; D012665:Semicircular Canals / Q000166:cytology* / Q000187:drug effects*; D012965:Sodium Chloride / Q000494:pharmacology*; D028021:Sodium-Potassium-Chloride Symporters; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013997:Time Factors
D002352:Carrier Proteins; D026902:Potassium Channel Blockers; D028021:Sodium-Potassium-Chloride Symporters; D008353:Mannitol; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium