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Figure 6 Sarcoplasmic Reticulum Calcium Clamping Abolishes Alternans in Modeled Endocardial Cells

(A) Odd (solid lines) and even (dotted lines) beats for a single endocardial cell at steady state with sarcoplasmic reticulum calcium uptake current (I_up) reduced by 70%, showing alternans in action potential (AP), intracellular calcium ([Ca]_i), L-type calcium current (I_CaL), and sarcoplasmic reticulum calcium (CaSR). (B) APs superimposed (blue line = odd; red line = even) for (left) I_CaL, (middle) [Ca]_i, and (right) CaSR, clamped to the odd traces in (A). Clamping to even beats did not change the results.