Fig. 2.

Raising dietary K⁺ counteracts hypertension in spontaneously hypertensive rats (SHR). A: at baseline, with dietary electrolytes at 0.2% NaCl and 0.5% K⁺, blood pressure (BP) is 148 mmHg. Raising dietary NaCl to 8% increases BP to 182 mmHg if K⁺ is kept at 0.5%, but BP does not increase if K⁺ is also raised to 2% (146 mmHg). [Redrawn from results of Ganguli and Tobian (18).] B: dietary K⁺ intake, under conditions of normokalemia, inhibits Na⁺ reabsorption via DCT NCC, which increases Na⁺ delivery downstream to ENaC, where Na⁺ reabsorption drives increased K⁺ secretion. Net result is increased excretion of Na⁺ and K⁺. C: summary of results from a small study of SHR fed 2% NaCl + 1% KCl or 2% NaCl + 4% KCl from 6 to 13 wk of age (37). Tail cuff BP [mean arterial pressure (MAP), mean of weekly measurements from weeks 11–14 after 3 wk of adaptation] was 24 mmHg lower in SHR fed 4% KCl; overnight urine Na⁺ (U_NaV) was marginally increased by 25%; NCC total abundance, measured by immunoblotting, was decreased ~15%, and ENaC activation, estimated from abundance of the cleaved (clvd) γ-subunit, was increased ~20%, supporting the model linking increased K⁺ secretion to decreased Na⁺ reabsorption.