Magnesium ion activity in the mammalian endolymph measured with ion-selective microelectrodes.
Level 5 - mechanism / opinion, no new human data
Animal bench measurement study (mechanism-based reasoning).
PubMed 3178561 · doi:10.1007/BF00464015
What was done
Researchers measured free Mg++ concentrations and endocochlear potentials in the endolymph of guinea pigs and chinchillas using Mg++-selective microelectrodes based on the neutral ligand ETH 1117. Calibration solutions mimicking endolymph background electrolytes were tested between 0.1 and 10 mM Mg++, yielding a potential change of 14.4 ± 3.0 mV.
What was found
In guinea pigs, the endocochlear potential was 82.0 ± 5.0 mV and the endolymph Mg++ concentration was 0.77 ± 0.29 mM. In chinchillas, the endocochlear potential was 84.4 ± 4.9 mV and the endolymph Mg++ concentration was 1.12 ± 0.24 mM.
Why it matters
This study provides quantitative baseline values for free magnesium in mammalian endolymph, informing models of inner ear electrochemical homeostasis, Na+, K+-ATPase dependence, and calcium interactions.
Limits
The abstract does not disclose sample sizes (number of animals or ears measured). Findings are derived entirely from animal models and may not fully reflect human inner ear physiology.
Cited by
- context Magnesium in the cochlear endolymph is depleted by loud sound, and magnesium supplementation protects against acoustic trauma and permanent hair cell loss.