Fig. 5. Dose-dependence of cuticular short-circuit current (I_sc) and transcuticular conductance (G_cut) inhibition by amiloride. A clamp voltage of 10 mV with reference to the apical side was maintained to force transcuticular NH₄⁺ fluxes. In four experiments on different isolated cuticles, amiloride was added at increasing concentrations to the external solution. (A) Mean I_sc plotted against the concentration of amiloride (in mol l^-1) in the external saline. (B) The I_sc data are shown in a Hanes-Woolf plot. The mean values of I_max (maximum short-circuit current) and K_ami (inhibition constant for amiloride) were obtained from plots for the individual experiments. (C) Mean G_cut plotted against the concentration of amiloride (in mol l^-1) in the external saline. (D) The G_cut data are shown in a Hanes-Woolf plot. The mean values of G_max (maximum transcuticular conductance) and K_Ami were obtained from plots for the individual experiments. Values are means ± S.E.M.