Figure 8

Intracellular pH regulation in ae3 ^−/− cardiomyocytes. Freshly isolated cardiomyocytes were loaded with 2 μM BCECF-AM for 30 min, placed in an Attofluor cell chamber and mounted onto an inverted epifluorescence Leica DMIRB microscope. A, In this representative experiment, WT cardiomyocytes were perfused with HCO₃ ⁻-containing Ringer’s buffer (open bar) until steady-state pH was reached and perfusion was switched to HCO₃ ⁻-containing Ringer’s buffer supplemented with 20 mM TMA (black bar). Perfusion was switched to the HCO₃ ⁻-containing Ringer’s buffer ~3 min later. At the end of the perfusion pH_i was clamped by the high K⁺/nigericin technique to convert fluorescent intensities to pH_i (not shown). B, Steady-state pH_i was measured as the pH_i value prior to induction of intracellular alkalosis. C, The rate of recovery of pH_i from imposed alkalosis was assessed as the first minute of pH_i recovery fitted by linear regression. *P < 0.05 compared to WT (ae3 ^+/+) (n = 4).