The Effects of Urethane on Rat Outer Hair Cells

Figure 2

The urethane-induced hyperpolarization of the OHC membrane potential. (a) A photograph showing the experimental setup for the whole-cell patch-clamp recordings. Urethane was delivered via pressure ejection from a micropipette positioned ~50 μm from the cell. The microphotograph was captured using an upright microscope under bright field illumination. The bar represents 20 μm. (b) Examples of membrane potentials recorded from OHCs clamped to zero membrane current during the delivery of a urethane puff (0.1 mM, 1 mM, 10 mM, 100 mM, or 500 mM concentration, timing denoted by the horizontal bar) or standard medium (0 mM). (c) The dose-response curve of the OHC membrane potential evoked by 0 mM (obtained from 4 cells), 0.1 mM (5 cells), 1 mM (3 cells), 10 mM (5 cells), 100 mM (5 cells), or 500 mM (4 cells) urethane. The data are presented as the mean values; the error bars represent the SD. The values are also normalized to the mean reduction evoked by 500 mM urethane. The smooth curve is the Hill equation with a half-activating concentration of 15.4 mM and a slope of 0.91.

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