Figure 8.

Blocking cysteines prevents HNO-induced SERCA2a activation and abates increase in sarcomere shortening in cardiomyocytes. (a) Cardiomyocytes resuspended in Ca²⁺-free assay buffer at pH 7.0 (0.5 mg total protein/ml), were incubated with vehicle or CPM (5 µM) for 15 min at room temperature. Following treatment with 0 or 100 µM AS/HNO, the samples were assayed for [Ca²⁺]-dependent ATPase activity at 1 µM [Ca²⁺]_free at 37°C. The data were normalized with respect to the activity of control samples (n = 4; *, P < 0.05). (b–d) Summary data of the impact of (b) AS/HNO (500 µM; n = 5 cells for each group; *, P < 0.05), (c) CPM (20 nM) followed by AS/HNO (500 µM; n = 9–14 cells for each group obtained from four to five different mice; P = NS), and (d) CPM (20 nM) followed by ISO (10 nM; n = 10 cells for each group obtained from four different mice; ***, P < 0.001 versus basal, ***, P < 0.001 versus CPM alone) on fractional sarcomere shortening (FS) expressed as fractional increase from diastolic levels for WT cardiomyocytes.