Ca 2+ channel nanodomains boost local Ca 2+ amplitude

concentration to channel flux. Ourestimate of G = 1.0 ± 0.2 mM/pA is nominally an order ofmagnitude larger than the widely quoted estimate of 100 μM/pAbased on diffusion theory (detailed below). Repeating theseanalyses using the initial rate of CDI (rather than steady state)yielded nearly identical results (SI Appendix, Fig. S3). This sug-gested that nanodomain Ca