| ObjectiveIncreasing evidence has shown the heart injury can develop as result of myocardial ischemia-reperfusion due to myocardial infarction and other cardiovascular disease. However, the mechanism on heart injury is not clearly. Resent studies show that myocardial apoptosis is the main form during the ischemia-reperfusion. The loss of mitochondrial membrane potential is notable characteristic of early apoptosis. Mitochondrial membrane was impaired, causing the release of cytochrome c and some apoptosis-inducing factors, which activated the caspase enzymes leading to the apoptosis. Nalxone is the endogenous apioid receptor specificity agent. But resent studies have found that it has protective effects against myocardial ischemia-reperfusion, and its protective mechanism is not fully understood. The aim of the study is to investigate the protective effects and the possible mechanism of the naloxone on the rats heart injury induced by myocardial ischemia-reperfusion in vitro. It can provide a theories basis for its clinical application on cardiovascular disease.MethodsA myocardial ischemia-reperfusion injury model in vitro was established with Wistar rats and they were divided into three groups : control group, ischemia-reperfusion group and ischemia-reperfusion with naloxone treatment group. Control group: Isolated rat hearts were perfused with the oxygen saturation desktop liquid in constant pressure and constant temperature lasting 105 minutes ,and perfusion is 6-8ml/min. Ischemia-reperfusion group (perfusion conditions as well as control group) : The isolated heart was pre-irrigated for 15 minutes, clipping desktop fluid channel dedicated ischemia for 30 minutes and reperfusion lasting 1 hour. Naloxone treatment group: The isolated heart was pre-irrigated for 15 minutes (this time used the oxygen saturation liquid containing naloxone and other conditions as well as ischemia-reperfusion group ), ischemia for 30 minutes and reperfusion for 1 hour. The isolated cardiomyocytes of ten animals in each group were used to detecting the mitochondrial membrane potential. The hearts of remaining ten animals in each group were fixed, embedded in paraffin for immunohistochemical staining ,and which were used to detect the expression of caspase-3 protein.ResultThe cells number of the decline in myocardial mitochondrial membrane potential is (17.49±1.57) %,(40.38±3.10) %,(23.19±3.14) % in three groups respectively . The results of immunohischemical staining showed that the naloxone can inhibit the expression of caspase-3 protein , and the expression of caspase-3 protein in ischemia-reperfusion was significantly higher than the naloxone treatment group and control group (P<0.05).ConclusionNaloxone has a protective effect on reperfusion injury after myocardial ischemia in rats in vitro. Naloxone markedly decreased the cells number of the decline in myocardial mitochondrial membrane potential. This effect maybe is related to the inhibition of mitochondrial membrane potential decline, protecting the integrity of the mitochondrial membrane, preventing the release of the Cytohrome C and apoptosis-inducing factor, thereby inhibition the myocardial apoptosis in myocardial ischemia-reperfusion and playing a protective role. Also naloxone direct down regulated the expression of caspase-3 protein, so that the cascade can' t continue and inhibit the cells apoptosis in myocardial ischemia-reperfusion ,play a protective role .
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