Fig. 1.
Terbutaline increases highly selective cation (HSC)-epithelial sodium channel (ENaC) activity in type 1 (T1) cells. A: results from 5 independent observations shown on dot-plot graphs with y-axis = ENaC activity (NPo), where N = number of channels and Po = open probability. NPo increased from 0.96 ± 0.61 to 1.25 ± 0.71 with stimulation by 20 μM terbutaline; P = 0.045. B: results from 5 independent observations shown on bar graph with y-axis = ENaC open channel probability (Po); P = 0.04. C: 5 independent observations shown on bar graph with y-axis = number of ENaC per patch (N); P = 1.0. Asterisk denotes significant difference. D: representative recordings taken from a continuous cell-attached patch-clamp analysis of a T1 cell before (control) and after 20 μM terbutaline treatment. Arrow indicates closed state, and downward deflections depict inward entry of Na ions. E: I/V curve of ENaC channels in T1 cells following terbutaline treatment. Conductance measurements (γ = 4.6 pS) indicate the channels are HSC channels.