Fig. 5

Modulation of SERCA activity by NCLX reduction in (a) DT40 B lymphocytes and (b) HL-1 cardiomyocytes. a ER Ca²⁺ uptake by wild type and NCLX^+/− DT40 cells. ER Ca²⁺ uptake were activated by applying 0.1 mM MgATP and 100 nM Ca²⁺ in Mag Fluo-4-loaded and permeabilized cells under conditions in which mitochondrial respiration was intact. The bar graph depicts the initial velocity of the ER Ca²⁺ increase. Data are mean ± SEM of independent recordings. Modified from Kim et al. [44]. b SR Ca²⁺ reuptake by HL-1 cardiomyocytes. Plasmid harbouring Cameleon D1ER, an indicator of SR Ca²⁺, was co-transfected with control (white) or NCLX siRNA (black) into HL-1 cardiomyoyctes. After emptying Ca²⁺ in SR with 10 mM caffeine, recovery of SR Ca²⁺ was measured. The bar graph depicts the recovery time constant τ, showing that SR Ca²⁺ reuptake was slower in NCLX knockdown cells. **p < 0.01, *p < 0.05. Modified from Takeuchi et al. [46]