Figure 4.

(a) ISL reduced the intracellular ROS levels in isolated mouse cardiomyocytes during hypoxia/reoxygenation. Intracellular ROS levels were measured by the fluorescent probe H₂DCFDA after treatment with ISL (100 μM) or DMSO (vehicle). ROS production was expressed as fluorescence intensity relative to untreated control cells. Data are presented as means ± SE (n = 4–6). *P < 0.05 versus normoxia vehicle; ^† P < 0.05 versus hypoxia vehicle; (b) ISL reduced mitochondrial membrane potential (Δψ) in isolated cardiomyocytes. Mitochondrial membrane potential (Δψ) was measured by JC-1 fluorescence assay. The result was presented as the ratio of red/green fluorescence measured at 590 nm and 530 nm, respectively. Values are means ± SE (n = 6–10). *P < 0.01 versus vehicle; (c) ISL treatment augmented glucose uptake of cardiomyocytes. The cardiomyocytes were preincubated for 30 min with or without ISL (100 μM) and/or insulin (10 nM), before addition of 2-deoxy-[1-³H]glucose for additional 30 min to measure glucose uptake. Values are means ± SE for 5 experiments. *P < 0.05 versus vehicle; ^† P < 0.05 versus insulin alone.