Critical role of bicarbonate and bicarbonate transporters in cardiac function

Figure 3 Ca²⁺ transient analysis in isolated rat myocytes bathed in CO₂/HCO₃^- buffer and in HEPES buffer. For recording of Ca²⁺ transients, isolated ventricular myocytes were loaded with fluo-4 acetoxymethyl ester (5 μmol/L, Molecular Probes, Eugene, OR) and activated with field stimulation at 0.5 Hz. Fluorescence signals were measured using a Nikon TE 2000 microscope and an InCyt Standard PM photometry system (Intracellular Imaging, Cincinnati, OH) as described previously[104]. A: Representative Ca²⁺ transients in HEPES and HCO₃^--containing buffers; B: Average Ca²⁺ transient (CaT) amplitudes and tau values, a measure of the rate of decay of the Ca²⁺ transient in HEPES and HCO₃^--containing buffers (n = 12). The same cells were imaged in both buffers. Myocytes were from the same preparations used in Figure 2, with statistical analyses performed using a paired t-test. No significant differences were observed.