In-Vitro Physiology Laboratory

Projects in the In-vitro Cochlear Physiology Laboratory are currently using a perfusion technique to examine inner and outer hair cell physiology. Results are expected to increase understanding of sensorineural hearing loss.

Principal Investigator: Jonathan H. Siegel
Frances Searle Building 2-258

Lab Project

Inner Hair Cell Physiology in Intact Perfused Cochleas. We have refined a method of maintaining the adult mammalian cochlea for prolonged periods in vitro using a perfusion technique. This has allowed us to study the physiology of single inner hair cells using whole-cell patch recording techniques. The inner hair cells in Mongolian gerbils express two voltage-dependent potassium currents similar to those described in guinea pigs by other investigators. However, one of these currents appears to become increasingly composed of sodium during prolonged depolarizations. A biophysical model developed by Ph.D. student, David Zeddies, demonstrated that even a small depolarization-activated permeability to sodium could easily send hair cells into negative energy balance and death. Another set of experiments has revealed the presence of a chloride conductance in outer hair cells that appears to be activated during the perfusion, resulting in swelling and eventual rupture of the cells. Either or both of the increased sodium or chloride currents could be part of a rapid mechanism of hair cell death that may play a role in sensorineural hearing loss.