Evidence for apical K conductance and Na-K-2Cl cotransport in the endolymphatic sac of guinea pig

The transepithelial potential in the endolymphatic sac (ESP) was recorded u p to 60 min after apical injection of ouabain, bumetanide, quinine, barium, tetraethylammonium, and 4-aminopyridine. After control injection, ESP decr eased by 74% and completely recovered at 30 min. After ouabain, barium: or quinine injection, the ESP time course was similar to that in the control g roup. After bumetanide, tetraethylammonium, or 4-aminopyridine injection, c omplete recovery was only observed at 60 min. These results suggest that ap ical K+ conductance and Na-K-2Cl cotransporter could be involved in the gen esis of ESP. (C) 1999 Published by Elsevier Science B.V. All rights reserve d.