Figure 4.

Effects of oxidizing and reducing reagents on SR Ca²⁺ leak in control and HF permeabilized myocytes. A, Representative recordings of intra-SR Fluo-5N fluorescence as measures of SR Ca²⁺ leak unmasked by inhibition of the SERCA pump with Tg (10 μmol/L) in control (left) and HF permeabilized myocytes (right) under baseline conditions and after treatment of the control and HF cells with DTDP (50 μmol/L) or DTT (1 mmol/L), respectively. The decline of Fluo-5N signal in the presence of Tg was fitted by exponential functions (red lines). B, Average time constants (from exponential fits) of SR Ca²⁺ leak for control cells at baseline (BL) conditions (856±191 s, n=12) or in the presence of DTDP (139±20 seconds; n=8) (black bars) and for myocytes from failing hearts at baseline conditions (337±52 seconds; n=10) or in the presence of DTT (625±140 seconds; n=6) (light bars). *P<0.05 vs baseline (BL), **P<0.05 vs control.