Fig. 3.

Disturbances in intracellular Ca²⁺ cycling as a key mechanism for the development of alternans.

(A) Ca²⁺ transient alternans recorded in voltage-clamped atrial myocytes under AP-clamp conditions when beat-to-beat V_m is kept constant. (B) Inhibition of cytosolic Ca²⁺ release by ryanodine abolishes AP alternans. APs and [Ca²⁺]_i recorded simultaneously from a current-clamped atrial myocyte.

Panel B is from [17].