RT Journal Article
SR Electronic
T1 Critical Roles of Transitional Cells and Na/K-ATPase in the Formation of Vestibular Endolymph
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 16541
OP 16549
DO 10.1523/JNEUROSCI.2430-11.2011
VO 31
IS 46
A1 Sylvain Bartolami
A1 Sophie Gaboyard
A1 Julie Quentin
A1 Cécile Travo
A1 Mélanie Cavalier
A1 Jacques Barhanin
A1 Christian Chabbert
YR 2011
UL http://www.jneurosci.org/content/31/46/16541.abstract
AB The mechanotransduction of vestibular sensory cells depends on the high endolymphatic potassium concentration ([K+]) maintained by a fine balance between K+ secretion and absorption by epithelial cells. Despite the crucial role of endolymph as an electrochemical motor for mechanotransduction, little is known about the processes that govern endolymph formation. To address these, we took advantage of an organotypic rodent model, which regenerates a genuine neonatal vestibular endolymphatic compartment, facilitating the determination of endolymphatic [K+] and transepithelial potential (Vt) during endolymph formation. While mature Vt levels are almost immediately achieved, K+ accumulates to reach a steady [K+] by day 5 in culture. Inhibition of sensory cell K+ efflux enhances [K+] regardless of the blocker used (FM1.43, amikacin, gentamicin, or gadolinium). Targeting K+ secretion with bumetanide partially and transiently reduces [K+], while ouabain application and Kcne1 deletion almost abolishes it. Immunofluorescence studies demonstrate that dark cells do not express Na-K-2Cl cotransporter 1 (the target of bumetanide) in cultured and young mouse utricles, while Na/K-ATPase (the target of ouabain) is found in dark cells and transitional cells. This global analysis of the involvement of endolymphatic homeostasis actors in the immature organ (1) confirms that KCNE1 channels are necessary for K+ secretion, (2) highlights Na/K-ATPase as the key endolymphatic K+ provider and shows that Na-K-2Cl cotransporter 1 has a limited impact on K+ influx, and (3) demonstrates that transitional cells are involved in K+ secretion in the early endolymphatic compartment.