Figure 2.

The protocol of pH changes (PPC) predicted delayed afterdepolarizations (DADs) on returning to normal pH. (A) Changes of CaMK_active, INCX, [Ca²⁺]_SR(max), [Ca²⁺]_i(max) and [Na⁺]_i(max) due to pH alterations in the PPC. (B) Time course of membrane potential (E_m), INCX, Irel, [Ca²⁺]_i and [Ca²⁺]_SR during acidosis (Black) and post acidosis (Red). Suprathreshold DADs marked by an asterisk and subthreshold DADs marked with an arrow are shown. CaMK_active, fraction of activated calcium/calmodulin-dependent protein kinase II; [Ca²⁺]_i(max), maximum cytoplasmic calcium concentration; [Ca²⁺]_SR(max), maximum sarcoplasmic reticulum calcium concentration; [Na⁺]_i(max), maximum intracellular sodium concentration; INCX, the sodium-calcium exchanger current and Irel, sarcoplasmic reticulum calcium release flux.