The Angiogenesis Effect Of Recombinant Growth Hormone On Ischemic Myocardium Of Acute Myocardial Infarction Rats

BackgroundThe presence of collateral vessels, which develop following coronary artery occlusion, has been familiar to clinicians for many years. Collaterals appear at the interface between normal and ischemic tissue in response to a gradually developing high-grade stenosis or occlusion. Blood flow through coronary collaterals may be sufficient to preserve wall motion and prevent ischemia at rest and may reduce or prevent ischemia during stress. The most important way by which coronary collaterals formed is known as angiogenesis. Angiogenesis involves extension of the already formed primitive vasculature by the sprouting of new capillaries through migration and proliferation of previously differentiated endothelial cells. Many soluble cytokines involves in it and have play essential roles, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and insulin–like growth factor-Ⅰ(IGF-Ⅰ)et al. Enhance this process by delivery of growth factors is therefore potentially to promote the angiogenesis.While ischemia from vascular occlusion upregulates expression of angiogenic growth factors, the fact that certain patients present with disabling angina indicates that such natural compensatory processes are not always sufficient. There are two possible explanations for this: either the production of angiogenic cytokines is inadequate, or patients'response to them is attenuated. These limitations can be overcomed in part by supplementation of angiogenic cytokines. This is called"therapeutic angiogenesis". Therapeutic induction of vascular growth may provide a treatment option for those patients with myocardial or peripheral ischemia who are not suited to conventional revascularization therapies.Human growth hormone (GH) is a 191 amino acid single-chain polypeptide with a molecular weight of 22KD. The GH receptor is expressed on cardiomyocytes, and expression in the heart appears to be higher than in many other tissues. Numerous functions have been attributed to it, including improve cardiomyocyte contractility, preserve cardiac...