Studies of cochlear outer hair cell membrane mechanics using optical tweezers

摘要

An optical tweezers system was used to study the mechanical characteristics of outer hair cell (OHC) and human embryonic kidney (HEK) cell plasma membranes. The effect of the cationic amphipath chlorpromazine (CPZ) on the equilibrium tethering force (F_(eq)), force relaxation time constant (τ), and effective membrane viscosity (η_(eff)) was measured. The F_(eq) for the OHC lateral wall plasma membrane was ～60 pN and was unchanged by addition of CPZ. A significantly greater τ value was observed in CPZ-treated OHCs (30.5 +- 12.6 s) than in control OHCs (19.0 +- 13.2 s). The F_(eq) and τvalues for control HEK cells were >60% lower than the respective OHC values but increased by ～3 times following CPZ addition. Effective viscosity ranged between 1.49-1.81 pN-s/μm for CPZ-treated OHCs. This represents a decrease from reported control OHC membrane viscosities.