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. 2020 Mar 20;318(6):H1357–H1370. doi: 10.1152/ajpheart.00481.2019

Fig. 8.

Fig. 8.

Ionic basis of synapse-associated protein 97 (SAP97)-M827T effects on the cardiac action potential (AP). A: SAP97-wild-type (WT) and SAP97-M827T coexpression increased Kv4.3 current in heterologous system. Representative whole cell recordings of Kv4.3 alone, coexpressed with SAP97-WT or SAP97-M827T in Chinese hamster ovary cells. B: current-voltage relationship for Kv4.3 control (n = 9), coexpression with SAP97-WT (n = 18), or SAP97-M827T (n = 18). All values represent means ± SE. Whisker plot (right) shows peak current density at +40 mV for Kv4.3 alone (n = 9), coexpressed with SAP97-WT (n = 18) or SAP97-M827T (n = 18). *P = 0.0199, Kv4.3+SAP97-M827T vs. Kv4.3+SAP97-WT; +P = 0.0284, Kv4.3+SAP97-WT vs. Kv4.3 + empty vector. Horizontal bars represent means; vertical bars, SD. C–E: simulated effects of SAP97-M827T on the right (RV) and left (LV) ventricular epicardial APs. C: Simulated transient outward K+ (Ito) traces during step depolarization for 120 ms to +40 mV from a holding potential of −90 mV. Solid line, WT; dashed line, SAP97-M827T. D: RV epicardial APs simulated using Ito expressed in the presence of WT and M827T-SAP97 incorporated into a modified Luo-Rudy II AP model. Basic cycle length (BCL) = 800 ms (75 beats/min). Solid line, WT; dashed line, SAP97-M827T. The 10th AP in the equilibration chain is displayed here; the AP shape does not change in subsequent cycles. E: simulated LV epicardial APs using a modified Luo-Rudy II AP model with Ito expressed in the presence of WT and SAP97-M827T. BCL = 800 ms (75 beats/min). Solid line, WT; dashed line, SAP97-M827T. Only the 10th AP in the equilibration chain is displayed here, the AP shape does not change in subsequent cycles.