Megahertz Sampling of Prestin (SLC26a5) Voltage-Sensor Charge Movements in Outer Hair Cell Membranes Reveals Ultrasonic Activity that May Support Electromotility and Cochlear Amplification.
Level 5 - mechanism / opinion, no new human data
Non-clinical bench biophysical study on animal cell membranes (CEBM level 5 by design analogy).
PubMed 36868859 · doi:10.1523/JNEUROSCI.2033-22.2023
What was done
Megahertz electrophysiological sampling was performed on outer hair cell membranes from guinea pigs (either sex) under voltage clamp. The authors extended measurements of prestin voltage-sensor charge movements and complex nonlinear membrane capacitance (cNLC) across a wide bandwidth up to 120 kHz, testing prestin displacement current noise against kinetic model predictions via the Nyquist relation and stationary measures.
What was found
Prestin charge movements yielded an order of magnitude larger response at 80 kHz than previously predicted. The characteristic cut-off frequency was observed at an intersection frequency of real and imaginary cNLC components near 19 kHz, which aligned with prestin displacement current noise spectra. The abstract does not report precise sample sizes or variance metrics.
Why it matters
It provides biophysical evidence that prestin-driven outer hair cell electromotility remains functionally viable at ultrasonic frequencies up to 120 kHz, resolving a long-standing controversy regarding whether prestin can support cochlear amplification in high-frequency mammalian hearing.
Limits
The abstract provides no specific sample sizes (n of cells or animals) or confidence intervals. Measurements reflect isolated membrane kinetics under voltage-clamp conditions, which do not directly quantify active mechanical force production or whole-organ cochlear micromechanics in living animals. Findings from guinea pigs may not generalize directly to all mammalian auditory systems.
Cited by
- supports Outer hair cells in the mammalian inner ear physically oscillate at audio frequencies up to 20,000 Hz in humans and up to 100,000 Hz in bats.