Hypoxic Preconditioning Early Effect Was Compared With Delayed Effect In Rat Myocardium

ObjectiveIschemic heart disease (IHD) is the leading cause of morbidity and mortality in the world. Scientist are looking for a kind of method which can prevent myocardium from ischemia/reperfusion insulting. In 1986, Murry et al found that several brief period of ischemia with intermittent reperfusion were shown to reduce infart size and introduced Hypoxic Preconditioning ( HPC) for the first time. In the subsequent years that followed, many scientist continue to research the preconditioning stimulus , namely how long and how many HPC requires brief period ischemia followed by reperfusion to trigger the response, and how long HPC protection can lasts. Our aim is whether three cycles of 5 min of hypoxia with intermittent 10 min reoxygenation trigger HPC early effect and delayed effect and to compare HPC early effect with delayed effect in rat myocardium. Our experiment make a primary feasibility study of HPC essential.Materials and Methodsmaterials1. Animals; forty -five 2-3 day neonatal WisterApparatus: hypoxic chamber, normoxic chamber, centrifuge, water bath box, spectrophotometric or auto multifunction biochemical analysis apparaus, microscope, desiccator, refrigeratory.Medicine:PBS, fetal bovine serum, 0. 08% pancreatin, DMEM, penicil-lin, streptomycin, HEPES, cytarabine, LDH enzyme assay kit MethodsThese studies were carried out using rat cardia cmyoctes in a cell cultured model. The myocardium were randomized into one of the three groups: namely sustain hypoxia control group, hypoxic preconditioning early effect group and hy-poxic preconditioning delayed effect group. LDH enzyme assay was respective performed before and after severe hypoxia in the first group, before and after HPC and severe hypoxia in the second group and the third group.ResultsLDH activity were same level before process in the culture medium of three groups. LDH activity were same level in after and before HPC in the culture medium of the second group and the third group. LDH activity were lower in the culture medium of the second group and the third group after sustained hypoxia than in the first group. LDH activity were lower in the culture medium of the second group after sustained hypoxia than in the third group.DiscussionOur experiment shows that HPC which requires three cycles of 5 min of hypoxia with intermittent 10 min reoxygenation trigger HPC early protection effect. This result is same as Murry et als observation which requires four 5 min cycles of HPC in dog heart and Cohen et als observation which requires 5 min hypoxia and 10 min reoxygenation of HPC in rabbit heart. It is unclear whether our experiment of the preconditioning stimulus is most power in rat myocardium. Our experiment shows that HPC which requires three cycles of 5 min of hypoxia with intermittent 10 min reoxygenation trigger HPC delayed protection effect. This result is same as Baxter GF et als observation which requires four 5 min cycles of HPC in rabbit heart and . Kuzuya T et al observation which requires four 5 min cycles of HPC in dog heart.In addition, Our experiment shows that HPC which requires three cycles of...