Fig. 4. High Na⁺ high Cl⁻ diet inhibits basolateral K⁺ conductance and K_ir4.1/5.1 activity in collecting duct principal cells.

Representative macroscopic currents in response to voltage steps from − 90 to + 60 mV (shown in inset) from the holding potential of − 60 mV (a), averaged current-voltage (I–V) relations (b), and the summary graph of resting basolateral membrane potential (c) in principal cells from mice kept on regular diet (0.3% Na⁺, 0.5% Cl⁻: RNa⁺ RCl⁻, black) and high NaCl diet (1.6% Na⁺, 2.4% Cl⁻: HNa⁺ HCl⁻, gray). d Representative continuous current traces from cell-attached patches monitoring basolateral 40 pS K_ir4.1/5.1 single channel activity in collecting duct principal cells for the regular (left) and high NaCl (right) conditions. Patches were clamped to −V_p = − 40 mV. “C” denotes non-conducting closed state. Summary graph of changes in open probability (e), number of active channels within a patch (f), and unitary current amplitude (g) of K_ir4.1/5.1 in principal cells from mice on regular diet and high NaCl diet. *Significant difference versus regular diet