Figure 3

Relationship between APD and CaT amplitude alternans. (a) Illustrates simultaneous measurements of AP and CaT recorded at 250, 230 and 210 ms of BCL. At the left side a moderate AP alternans (black) coupled with marginal alternans of the CaT (blue curve), measured at 250 ms. (a) Right side illustrates marked AP alternans (black) associated with pronounced CaT alternans (blue) monitored at 210 ms. (b) Illustrates the APD₉₀ alternans amplitude plotted against the extent of CaT alternans defined as CaT peak alternans ratio, at various BCLs. The grey line represents the linear regression of the points. (c) Depicts rapid pacing by non-alternating membrane potential, (upper curve) failed to induce CaT alternans under perforated patch-clamp condition. Parallel measured membrane current (middle curve) and CaT (lower curve) traces at a basic cycle length of 210 ms are shown. The evoked membrane currents were identical, and the evoked CaTs exerted negligible alternans.