FIGURE 1.

Osmotic swelling potentiates RA-MA currents in cultured DRG neurons. A, images show a DRG neuron at initial time (left) and 20 min (right) after establishing the whole-cell mode with a recording electrode that contained a hypertonic recording internal solution (420 mosm). The positions of the recording electrode and mechanical probe are indicated by a white and a black star, respectively. B, summary data of the osmotic swelling expressed as increases of cell diameters over time after establishing the whole-cell mode (n = 22). C, three sample traces show the mechanically activated currents evoked by a 7-μm membrane displacement step at the initial time (black), 14 min (red), and 20 min (blue) after establishing the whole-cell mode. The membrane displacement step is indicated above the current traces. The traces also include continual membrane tests by voltage steps of 5 mV at the interval of 100 ms. D, summary data of the increases of RA-MA currents over time after establishing the whole-cell mode with hypertonic (red circles, n = 18) or isotonic (black squares, n = 20) recording internal solution. E, decay time constants of RA-MA currents at initial time, 16 and 30 min after establishing the whole-cell mode with hypertonic (solid bars, n = 14) or isotonic (open bars, n = 30) recording internal solution. F, latency of RA-MA current onset at initial time, 16 and 30 min after establishing the whole-cell mode with hypertonic recording internal solution (n = 10). Data represent mean ± S.E., *, p < 0.05; **, p < 0.01; ***, p < 0.001, compared with the value at initial time.