Development of monovalent ions in the endolymph in mouse cochlea.
The present study was designed to clarify the chronological developmental process of monovalent ions (Na(+), K(+), Cl(-)) in the endolymph of the mouse in relation to the development of the endocochlear potential (EP). The EP and ionic concentrations were measured simultaneously with the ion-sensitive double-barreled microelectrodes from the scala media of the basal turn. The EP increased abruptly 7 days after birth (DAB) and reached approximately 80 mV 14 DAB. In the earliest postnatal days, the endolymphatic Na(+) concentration was significantly higher than that in adult mice, however, the K(+) and the Cl(-) concentrations were lower. The concentrations of all the monovalent ions in endolymph reached adult levels at 7 DAB when the EP was still under 20 mV. These data strongly suggest the presence of a different mechanism between the production of monovalent ions, especially of high K(+) in the endolymph and that of EP.
Yamasaki
M
M
Department of Otolaryngology, Miyazaki Medical College, Miyazaki, Japan.
Komune
S
S
Shimozono
M
M
Matsuda
K
K
Haruta
A
A
D000818:Animals; D000831:Animals, Newborn; D002712:Chlorides / Q000378:metabolism*; D003051:Cochlea; D004587:Electrophoresis, Agar Gel; D004710:Endolymph / Q000378:metabolism*; D008564:Membrane Potentials; D051379:Mice; D008813:Mice, Inbred ICR; D011188:Potassium / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D002712:Chlorides; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium