Figure 6: SIL Preserves the Oxidant/Antioxidant Balance in Cardiomyocytes Infected With

(A) Cardiac myocytes were infected with T. cruzi (cell/parasite ratio 1:5), and incubated for 24 h in the presence or absence of 10 nmol/l sildenafil. Cells were loaded with BCECF (fluoresces at normal pH, a–c), Fluo-4 (fluorescence shows intracellular Ca+2 level, d–f), H2DCFDA (oxidized by intracellular reactive oxygen species [ROS] to fluorescent dichlorodihydrofluorescein [DCF], g–i), or DHE (oxidized by intracellular ROS to fluorescent ethidium, j–l). Shown are the representative images (magnification 40×), captured by fluorescence microscopy. (B–D) Cardiac myocytes were infected with Tc (±SIL). Bar graphs show (B) ROS release by an Amplex red assay, (C) NAD+/NADH ratio, and (D) cell viability by MTT assay. (E) Cardiac myocytes were transfected with pBI.EGFP-MnSOD expression plasmid, infected with T. cruzi, and incubated in the presence or absence of sildenafil for 24 h. Bar graph shows MnSOD expression by EGFP-dependent fluorimetry. OD = optical density; RFU = relative fluorescence units; other abbreviations as in Figure 1.