Figure 5.
Graded release, variable gain, effect of dyad properties on ECC, and rate dependence of myoplasmic Nai and Cai. (A) Peak LCC Ca flux and peak Ca release flux as a function of transmembrane voltage. (B) Normalized peak LCC Ca flux and peak Ca release flux. (C) ECC gain for three conditions: 1), control (100/15 RyR2/LCC ratio, 2 × 10−19 L dyadic volume); 2), 50/7 RyR2/LCC ratio, 2 × 10−19 L dyadic volume; and 3), 100/15 RyR2/LCC ratio, 6 × 10−19 L dyadic volume. Initial conditions were those of a paced myocyte at 1 Hz. After 5 ms the cell was clamped at the voltage indicated on the x axis. (D) Myoplasmic Nai and Cai rate dependence. Steady-state (after 1000 beats of pacing) Nai, peak Cai and diastolic Cai as a function of cycle length (CL).