Fig. 2.

Effect of decreasing extracellular K⁺ concentration ([K⁺]_o) on ROMK currents in the rat cortical collecting duct (CCD). A: whole-cell recording showing outward currents at a holding potential of 0 mV. Whole-cell clamps were formed in the presence of 10 mM [K⁺]_o. Currents were stable in the presence of 10 mM [K⁺]_o but declined with 1 mM [K⁺]_o. At the end of the recording Tertiapin-Q (TPNQ; 100 nM) was added to the medium to measure the ROMK-specific currents. B: summary of 8 similar pairs of experiments. Data represent means ± SE. *P < 0.05, significant difference.