Perfusing isolated rat hearts with hydrogen peroxide: an experimental model of cardiac dysfunction caused by reactive oxygen species

Abstract

A model of cardiac dysfunction induced by reactive oxygen species (ROS) was established by adding hydrogen peroxide (H₂O₂) to the perfusate of isolated, Langendorff-perfused rat hearts, and the mechanism of functional injury was investigated. The following groups were included: 1 (n = 7), control perfusion; 2 (n = l1), perfusion with H₂O₂ (180 μmol 1^{− 1}) for 10 min followed by recovery for 50 min; 3 (n=4), control perfusion with N-acetylcysteine (NAC, 100 pol 1⁻¹); 4 (n = 7), perfusion with H₂O₂ and NAC; 5 (n=4), control perfusion with thiourea (15 mmol l⁻¹), 6(n = 7), H₂O₂ and thiourea together; 7 (n=4), control perfusion with catalase (150 U ml⁻¹); 8 (n = 7), catalase and H₂O₂, 9 (n = 4), control perfusion with deferoxamine (5 mmol 1⁻¹); and 10 (n = 7), deferoxamine and H₂O₂. coronary flow (CF), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), and heart rate (HR) were measured. All values are mean ± SEM. When given alone, catalase, thiourea, NAC and deferoxamine did not influence left ventricular pressures, but NAC, catalase and thiourea increased CF. H₂O₂ increased CF (maximum 146 ± 6% of baseline value after 5 min, p < 0.001 compared to group l), decreased LVDP (minimum 14 ± 5% of baseline value after 10 min, p < 0.0004), and increased LVEDP (from 0 mmHg to a maximum of 54 ± 7 mmHg after 5 min recovery, p < 0.0003). All these changes gradually reversed during recovery. Catalase and thiourea both inhibited the H₂O₂-induced effects, but catalase inhibition was more complete. Neither NAC nor deferoxamine had any effect on H₂O₂-induced cardiac dysfunction. In conclusion, H₂O₂ perfusion is a convenient and reversible model of ROS-induced functional injury to isolated rat hearts. H₂O₂, rather than the hydroxyl radical, seems to be the main injurious ROS in this model.

Key Words:

• antioxidants
• catalase
• deferoxamine
• hydrogen peroxide
• oxygen free radicals
• N-acetylcystein
• thiourea