Functional and molecular mechanism of intracellular pH regulation in human inducible pluripotent stem cells

Figure 5 Steady-state pH_i in HEPES and 5% CO₂/HCO₃^--buffered solution and the change in the expression of pH_i regulators during the loss of pluripotency in human induced pluripotent stem cells. A: The resting pH_i was a steady-state taken from the completely recovered pH_i after intracellular acidification or alkalization. The dotted line indicates the value of the resting pH_i; B: The max/min chart of the resting pH_i in hiPSCs was collected from A (n = 20) and Figures 4C and D (n = 5). The means of the resting pH_i in HEPES and 5% CO₂/HCO₃^--buffered solution were found to be 7.50 ± 0.01 and 7.68 ± 0.01, respectively. After treatment with H₃₀ and S₉₀ in 5% CO₂/HCO₃^--buffered solution, the resting pH_i shifted to 7.66 ± 0.02 and 7.46 ± 0.02, respectively; C: Immunoblot analysis of the expression of NHE1, NHE3, V-ATPase, NBCe1, NBCe2, NBCn1 and OCT4 in hiPSCs in different culture media for different days (E8 and E6-1d to E6-4d). The histograms in B display the mean and the min to max values. hiPSCs: Human induced pluripotent stem cells; NHE: The Na⁺/H⁺ exchanger; NBC: The Na⁺/HCO₃^- cotransporter; V-ATPase: Vacuolar-ATPase.