Effect of gtl-1 and gon-2 loss-of-function mutations on whole cell current. (A) Mean whole cell current amplitude in intestinal cells cultured from wild-type, gtl-1 mutant, and gon-2 mutant worms. Values are means ± SEM (n = 11–22). *, P < 0.01, compared with wild-type worms. **, P < 0.002, compared with gtl-1 mutant worms. All worm strains were grown at 25°C. (B) Current-to-voltage relationships of whole cell currents measured in intestinal cells cultured from wild-type and gon-2;gtl-1 double mutant worms. Wild-type intestinal cells were patch clamped in a bath solution containing 100 mM La³⁺, which completely inhibits I_ORCa (see Fig. 6 A). Remaining current shows a near linear current-to-voltage relationship and E_rev near 0 mV and is defined as leak current. Current-to-voltage relationship of gon-2;gtl-1 double mutant whole cell currents is also near linear with a near 0 E_rev. Data shown are the means of currents recorded from four wild-type cells and five gon-2;gtl-1 double mutant cells. Currents were elicited by ramping membrane potential from −80 to + 80 mV at 215 mV/s. Red symbols and error bars are mean ± SEM error currents measured at holding potentials of −80 and + 80 mV. Mean currents measured at −80 and + 80 mV and E_rev values were not significantly (P > 0.3) different for wild-type cells treated with La³⁺ and gon-2;gtl-1 double mutant cells.