Effect of Ca²⁺ Efflux Pathway Distribution and Exogenous Ca²⁺ Buffers on Intracellular Ca²⁺ Dynamics in the Rat Ventricular Myocyte: A Simulation Study

Figure 3

Effect of partial localization of NCX exchange (a), sarcolemmal Ca²⁺ pump (b), and SERCA (c) at the dyads on the amount of Ca²⁺ (𝑛_Ca) transferred through 𝐼_NaCa, 𝐼_pCa, 𝐽_up, and 𝐼_Ca; the peak value of Ca²⁺ transients in the t-tubular dyadic space ([Ca²⁺]_dt,peak) and in the cytosol ([Ca²⁺]_c,peak); the end-diastolic level of Ca²⁺ concentration in the network SR ([Ca²⁺]_NSR,end); and action potential duration at 50% repolarization (APD₅₀) during a steady-state cycle at 5 Hz. The fraction of all three transporters at the dyads was increased separately from control (𝑓_NaCa,d=𝑓_pCa,d=𝑓_up,d=0) to 0.1, 0.2, and 0.3. All values are expressed as a percentage relative to those obtained in control conditions.

(a)

(b)

(c)