Fig. 2.

Insulin upregulates ROMK channel activity in the rat CCD. A: typical trace from a principal cell of a control CCD. The animal was on normal chow. Currents were monitored at 0 mV while 10⁻⁷ M tertiapin-Q (TPNQ) and 5 mM Ba²⁺ were added sequentially to the superfusate. The dotted line indicates the 0-current level. B: similar trace from a principal cell of an insulin-treated CCD. C: summary of I_SK measured as the change in current after addition of TPNQ in control and insulin-treated cells from animals on control or high-K diets. Values are means ± SE for 26 cells (control diet) and 7–10 cells (high-K diet). *Statistical significance (P < 0.05 vs. control values).