Figure 7. Elevated [Na⁺]_i impaired Ca²⁺ extrusion in 7-week KO.

A, SBFI F₄₁₀/F₅₉₀ ratios were increased in 7-week KO indicating cytosolic Na⁺ accumulation (n= 9, 9, 13, 10 (order as in key here and in E)). B, expression of NKA α₁ and α₂ isoforms (n= 6 all groups). C, NKA currents obtained by rapid elevation of extracellular [K⁺]_i were subdivided into α₁ and α₂ components based on sensitivity to 5 μm ouabain (n for 7-week FF = 10, 7-week KO = 6). D, Ca²⁺ extrusion during NKA blockade by 1 mm ouabain, as estimated by half-decay time of Ca²⁺ transients during caffeine (n for 7-week FF = 10, 7-week KO = 10). E, Ca²⁺ transients following dialysis with 6 mm[Na⁺]_i (n= 19, 11, 20, 19). (For panels A–C, *P < 0.05 vs. equivalent FF; panel D, *P < 0.05 vs. untreated; ‡P < 0.05 vs. equivalent 7-week FF; panel E, *P < 0.05 vs. equivalent FF, ‡P < 0.05 vs. equivalent 4-week).