Fig. 2.
Carbenoxolone (CBX) abolishes spike-like currents and increases input resistance in chromaffin cells. Ai: electrical echoes were evoked from a voltage-clamped cell as in Fig. 1 over a 20-min time course to determine stability of the response (t = 0, 10, and 20 min). Region shaded in grey represents the integral of the echo, which is quantified in Aii and in subsequent figures. Aii: quantified data from each time point were plotted as means ± SE (n = 10 echoes/time point; P = 0.996 by ANOVA). Bi: effect of CBX on echo charge was tested. Cells were categorized as coupled if AP echoes were present at t = 0 min. An adrenal slice containing a coupled cell pair was bath-treated with 100 μm CBX. Echo charge was determined by current integration as above. Bii: echo integral (Int) data from all CBX time points (0, 10, and 20 min) were pooled, quantified, and plotted as means ± SE (n = 16 echoes/time point; *statistical significance of 0- and 20-min time points with P = 0.007 by Student's t-test). Ci: input resistance (Rmemb) was calculated using the same CBX treatment time course as in Bi. Cells were hyperpolarized to −130 mV from the holding potential of −80 mV to evoke a passive current to calculate membrane resistance (RMemb) of the cell. Representative current traces for the CBX t = 0-min and CBX t = 20-min time points are provided. Bii: this procedure was repeated at the 0-, 10-, and 20-min time points, and the RMemb. was calculated, pooled, and presented as means ± SE (n = 25, 9, and 9 cells for 0-, 10-, and 20-min time points, respectively; *statistical significance of 0- and 20-min time points at P = 0.002).