Measurements of ionic concentrations along with endocochlear potential in wild-type and claudin 14 knockout mice

Publication date: Available online 12 August 2017
Source:Auris Nasus Larynx
Author(s): Yuka Shiraiwa, Eriko Daikoku, Masahisa Saito, Yui Yamashita, Takaya Abe, Fumihito Ono, Takahiro Kubota
ObjectiveTo examine whether the changes in endolymphatic ion concentrations were involved in hair cells degeneration in claudin-14 knockout (KO) mice (Cldn14^−/−), we measured the endocochlear potential (EP) along with concentrations of K⁺, Na⁺, H⁺, or Ca²⁺ ([K]e, [Na]e, pHe, [Ca]e) in Cldn14^−/−, in which hair cells were selectively damaged, and compared with measurements in wild type mice (Wt).MethodsWe used the Cldn14^−/− from 3 weeks of age, in which the auditory brain responses (ABR) was severely diminished. Using double-barreled ion-selective microelectrodes, we measured [K]e, [Na]e, pHe, and [Ca]e in both Wt and Cldn14^−/− at 8–10 weeks of age.Results(1) In Wt, the EP was +92mV. [K]e, [Na]e, pHe, and [Ca]e were 169mM, ∼1.0mM, 7.50, and 395nM, respectively. In the Cldn14^−/−, the EP was +96mV. [K]e, [Na]e, pHe, and [Ca]e were 167mM, ∼1.0mM, 7.73, and 179nM, respectively. No significant differences in the above values were observed between Wt and Cldn14^−/−. (2) A significant linear correlation between EP and [Ca]e (R=0.93) was observed for both Wt and Cldn14^−/−, but no correlation was observed between EP and K⁺, Na⁺, or H⁺.ConclusionThese findings suggest that (1) the changes in endolymphatic ion concentrations might not be involved in hair cells degeneration in Cldn14^−/−, (2) [Ca]e might be regulated by EP in both Wt and Cldn14^−/−.



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