Fig. 5.

I_f contributes substantial inward and outward charge movement during the SAM AP. (A) Representative calculated net current (black) and measured ivabradine-sensitive I_f (red) during a single sinoatrial AP (Top) in 1 nM isoproterenol or in 1 µM isoproterenol. Horizontal lines indicate zero current. (B) Average (± SEM) ivabradine-sensitive inward (circles) and outward (diamonds) charge movement as a fraction of the net charge during a single AP in 1 nM (black) and 1 μM (red). Individual recordings in 1 nM isoproterenol (gray) or 1 µM isoproterenol (pink) are shown using the smaller symbols. Number of replicates and details of statistical tests can be found in SI Appendix, Table S3.