| Preconditioning not only yielded a protection on ischemia injury, but also worked out protection on multiply injury such as trauma, burn, oxidative stress and ROS. Myocardial ischemia preconditioning phenomena provide evidence for protective responses to ischemia myocardium. Any satisfactory preconditioning approach hasn't been found in clinic up to now. It was found, recently, that mitochondrial ATP-sensitive potassium (mitoK(ATP) channels opener could mimic ischemia preconditioning (IPC) protection effects by maintaining myocardial contraction function and reforming the myocardium in a graded pattern as assessed by myocardial infarct size estimation. As a specific mitoK(ATP)channel blocking Agent, 5-HD was given, this phenotype of protection effect disappeared, suggesting that preconditioning protection effects targeted mitochondrial ATP-sensitive K+ channel openness. However, the exact mechanism of these protection effects hadn't been clarified yet.Reactive oxygen species (ROS) were one of the vital factors in ischemia reperfusion injury. But it was found that a sprinkle free radicals, developed from brief period ischemia, enormously relieved myocardial infarction from subsequent severe ischemia. It might have triggered stress reaction in body and engendered a small quantity ROS that activated mitoK(ATP) channel open. On account of Pinacidil was a kind of K(ATP) opener, we suspected that if suitable doses of Pinacidil was given before impairment, which made mitoK(ATP) open ahead of gross injury, the protection effects would be visualized in injured myocardium. Based on the above-mentioned deduction, we prepared to use Pinacidil pretreating burned rats and H2O2-treated cardiomyocytes model, and observed protection effect on injured myocardia. Furthermore, we tried to reveal its mechanism. Our intention was to offer experimental gist for preventing and treating hurt myocardium.Material and MethodsBoth in vivo and in vitro study were carried out in the study.1. In vivo study, Rats were randomly separated into three groups: the control group, the burned group and the Pinacidil preconditioning group (Pinacidil treated before burn). Every group had 8 rats. Pinacidil preconditioning was done by injection of Pinacidil (50 V-g/kg) half an hour ahead of reproducing model of 30% TBSA of full-thickess burn rats. Our purpose was to determine if pincidil preconditioning can protect rats myocardium from severe burn. Rats heart function and hemodynamics were monitored by left common carotid artery cannulatio, myocardial mitochrodia were abstracted by differential centrifugation, then respiratory function, MDA and puperoxide anions were detected, TEM electron microscope was used to observe myocardial mitochondrial ultrastructural changes, in this study. We hope to do something for revealing the pharmacological mechanism of Pinacidil preconditioning on protection of myocardium.2. In vitro study, the primary neonate rat cardiomyocytes were isolated and cultured, cells were vaccinated into 24 or 96 cultivated well by density of 1X 105/ml or 5X 105/ml respectively. Cells were divided into 4 groups: the control group, the H2O2 group(400 u mol/L H2O2), the PIN group(l X 10-6 mol/L PIN+ H2O2 group) and the 5-HD group(l X 10-4mol/L 5-HD+ PIN group). Every group had three duplicate well. Pinacidil was given before H2O2 impariments. Activity and vitality were investigated by MTT, cytochrome C was sensed by immunohistochemistry assay, and mitochondrial membrane potential was detected by laser confocal microscopy. We aimed at that whether Pinacidil preconditioning could influence cardiac myocytes mitochondrial respiratory function, survival and whether have effect on mitochondrial membrane permeability and stability.Results1. Pinacidil preconditioning on hemodynamic and heart function in rats with 30% of III degree burn on their back skinA dramatic descent of SP, DP, MAP occurred right in the end of burn immediately. And a reversion was seen apparently one hour after burn without achieving to normal function. At followi...
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