Abstract Objective To report a new method of myocardial preconditioning named hyperoxic preconditioning (HOP). Methods The adult Wister rats were preexposed to 80%-85% of oxygen, 1 atm, 6 h per day for 7 days (HO ...Abstract Objective To report a new method of myocardial preconditioning named hyperoxic preconditioning (HOP). Methods The adult Wister rats were preexposed to 80%-85% of oxygen, 1 atm, 6 h per day for 7 days (HO groups, n=15) or just stayed in room air for 7 days (Control groups, n=15), they were killed at 12 hrs after HO protocol for the experiments. Each of groups was divided randomly into 3 subgroups (n=5 for each subgroup), so there were altogether 30 rats in 6 subgroups. HO 1 and Control 1: The expressions of Mn SOD mRNA in myocardium were determined by Northern Blot, the lung wet weight was measured and the lung tissue was observed by electron microscopy. HO 2 and Control 2: The isolated heart with Langendorff method underwent 60 min ischemia followed by 60 min reperfusion. HO 3 and Control 3: The isolated Langendorff heart underwent 10 min ischemia followed by 60 min reperfusion. The antioxidant enzyme activities of total SOD, GSH px and CAT in myocardium and the activities of total SOD (in all 2 and 3 subgroups) and CK (only in 2 subgroups) in coronary effluent were measured. Experimental Animal Laboratory, Section of Cardiology, Chinese PLA General Hospital, Beijing 100853, China Results The expressions of Mn SOD mRNA in myocardium were stronger in HO 1 than in control 1 subgroup; the activities of total SOD (83.64%±0.50% vs 76.78%± 1.71%, P<0.05), GSH px (0.97±0.17 vs 0.60± 0.05 μmol·min -1 ·g -1 , P<0.01) in myocardium were significantly higher in HO 2 than in control 2 subgroups. Also the activities of total SOD (90.10%±1.93% vs 85.14%±1.42%, P<0.05), GSH px (1.16±0.13 vs 0.61±0.12 μmol·min -1 ·g -1 , P<0.05) in myocardium were higher in HO 3 than in control 3 subgroups. The total SOD activities in coronary effluent at all the sampling time after reperfusion were higher in HO 2 and HO 3 than in their controls respectively (all P<0.05). The activities of CK in coronary effluents were lower in HO 2 than in control 2 at 30 min and 60 min after reperfusion (56.7±9.6 vs 97.0±11.1 and 87.0±24.5 vs 137.7±31.0 IU·min 1 ·g 1 , both P<0.05). The lung wet weights and the observations by electron microscopy did not reveal any damage in the lung tissue. Conclusion HOP can diminish myocardial necrosis, induce the increased expression of Mn SOD mRNA and the activities of antioxidant enzymes total SOD and GSH px in the subsequent lethal ischemia and reperfusion in rat heart, and it can not cause amy damage in rat lung.展开更多
Background: By lowering the oxygen fraction of the reperfusate, the reactive oxygen-derived free radicals can be reduced thus facilitating myocardial recovery during weaning from cardiopulmonary bypass and after surge...Background: By lowering the oxygen fraction of the reperfusate, the reactive oxygen-derived free radicals can be reduced thus facilitating myocardial recovery during weaning from cardiopulmonary bypass and after surgery. Materials & Methods: Thirty patients undergoing mitral valve replacement were randomly exposed to an oxygen fraction of 0.7 (hyperoxic, n = 15) or 0.5 (normoxic, n = 15) during reperfusion. Hemodynamic variables, number of patients requiring additional inotropes and who developed new arrhythmia, duration of ventilation and intensive care unit stay, arterial blood gas and renal function were measured. Results: The demographic data, duration of cardiopulmonary bypass, aortic cross clamp time, duration of mechanical ventilation, intensive care unit stay, additional inotropes, arrhythmia after reperfusion and renal function were similar in both groups. Arterial blood gas analysis was not significantly different, except for the low oxygen partial pressure in the normoxic group during reperfusion. With regard to hemodynamic variables, mean arterial pressure of the hyperoxic group was higher one hour after the cross clamp release. Hemodynamic variables were comparable in all other time periods. Conclusion: By reducing the oxygen concentration during reperfusion, the clinical outcomes in terms of inotropes usage, new arrhythmia after reperfusion, renal function, duration of ventilation and intensive care unit stay were not significantly altered.展开更多
文摘Abstract Objective To report a new method of myocardial preconditioning named hyperoxic preconditioning (HOP). Methods The adult Wister rats were preexposed to 80%-85% of oxygen, 1 atm, 6 h per day for 7 days (HO groups, n=15) or just stayed in room air for 7 days (Control groups, n=15), they were killed at 12 hrs after HO protocol for the experiments. Each of groups was divided randomly into 3 subgroups (n=5 for each subgroup), so there were altogether 30 rats in 6 subgroups. HO 1 and Control 1: The expressions of Mn SOD mRNA in myocardium were determined by Northern Blot, the lung wet weight was measured and the lung tissue was observed by electron microscopy. HO 2 and Control 2: The isolated heart with Langendorff method underwent 60 min ischemia followed by 60 min reperfusion. HO 3 and Control 3: The isolated Langendorff heart underwent 10 min ischemia followed by 60 min reperfusion. The antioxidant enzyme activities of total SOD, GSH px and CAT in myocardium and the activities of total SOD (in all 2 and 3 subgroups) and CK (only in 2 subgroups) in coronary effluent were measured. Experimental Animal Laboratory, Section of Cardiology, Chinese PLA General Hospital, Beijing 100853, China Results The expressions of Mn SOD mRNA in myocardium were stronger in HO 1 than in control 1 subgroup; the activities of total SOD (83.64%±0.50% vs 76.78%± 1.71%, P<0.05), GSH px (0.97±0.17 vs 0.60± 0.05 μmol·min -1 ·g -1 , P<0.01) in myocardium were significantly higher in HO 2 than in control 2 subgroups. Also the activities of total SOD (90.10%±1.93% vs 85.14%±1.42%, P<0.05), GSH px (1.16±0.13 vs 0.61±0.12 μmol·min -1 ·g -1 , P<0.05) in myocardium were higher in HO 3 than in control 3 subgroups. The total SOD activities in coronary effluent at all the sampling time after reperfusion were higher in HO 2 and HO 3 than in their controls respectively (all P<0.05). The activities of CK in coronary effluents were lower in HO 2 than in control 2 at 30 min and 60 min after reperfusion (56.7±9.6 vs 97.0±11.1 and 87.0±24.5 vs 137.7±31.0 IU·min 1 ·g 1 , both P<0.05). The lung wet weights and the observations by electron microscopy did not reveal any damage in the lung tissue. Conclusion HOP can diminish myocardial necrosis, induce the increased expression of Mn SOD mRNA and the activities of antioxidant enzymes total SOD and GSH px in the subsequent lethal ischemia and reperfusion in rat heart, and it can not cause amy damage in rat lung.
文摘Background: By lowering the oxygen fraction of the reperfusate, the reactive oxygen-derived free radicals can be reduced thus facilitating myocardial recovery during weaning from cardiopulmonary bypass and after surgery. Materials & Methods: Thirty patients undergoing mitral valve replacement were randomly exposed to an oxygen fraction of 0.7 (hyperoxic, n = 15) or 0.5 (normoxic, n = 15) during reperfusion. Hemodynamic variables, number of patients requiring additional inotropes and who developed new arrhythmia, duration of ventilation and intensive care unit stay, arterial blood gas and renal function were measured. Results: The demographic data, duration of cardiopulmonary bypass, aortic cross clamp time, duration of mechanical ventilation, intensive care unit stay, additional inotropes, arrhythmia after reperfusion and renal function were similar in both groups. Arterial blood gas analysis was not significantly different, except for the low oxygen partial pressure in the normoxic group during reperfusion. With regard to hemodynamic variables, mean arterial pressure of the hyperoxic group was higher one hour after the cross clamp release. Hemodynamic variables were comparable in all other time periods. Conclusion: By reducing the oxygen concentration during reperfusion, the clinical outcomes in terms of inotropes usage, new arrhythmia after reperfusion, renal function, duration of ventilation and intensive care unit stay were not significantly altered.
