| Background With the widespread use of percutaneous transluminal coronary angioplasty (PTC A) in treatment of coronary heart diseases, vascular restenosis after the operation becomes the hot research topic. It was found that proliferation, migration and development of extracellular matrixes (ECM) of the vascular smooth muscle cells (VSMCs) to form the neointima were the main reasons of the restenosis. Under physical conditions, the vessel contraction / growth stimulator and dilatation / growth inhibitor are in dynamic equilibrium. After PTC A, the coronary endothelia were injured and dysfunctional. The balance was broken and many growth factors, protooncogenes were abnormally expressed and excreted, as a result, the phenotype of the VSMCs were changed from adult type (contraction/ silence) to embryonic type (synthesis/excretion) and ECMs were excreted. The vasoactive agents stimulated proliferation of smooth muscle cells through mitogenic effects. Because lots of growth factors had taken part in thisprocess, it's useless to inhibit one or few factors to prevent restenosis. Researches had found that many growth factors such as PDGF, IGF-1, bFGF, ET-1, AngII and so on stimulated cell proliferation through activation of sodium/ hydrogen exchanger (Na+/H+ exchanger, NHE), which might be an important regulator in cellular proliferation.NHE, also named Na+/H+ antiporter, is a ubiquitous membrane transport protein. Six isoforms have been found and the NHE-1 isoform is the major form in cardiac muscles and vessel smooth muscles, which is sensitive to Amiloride and its analogues. NHE is an important regulator to the intracellular H+ and Na+ through exchanging intracellular H+ for extracellular Na+ in 1:1 ratio. Protein kinase C (PKC) can lead to NHE phosphorylation so as to activate it. Other agents including mitogen-activated protein kinase(MAPK) pathway, calmodulin and factors depending on Ca2+ such as thromboxane may also active NHE. In vivo and in vitro tests had displayed that NHE activation had taken part in cellular proliferation. In myocardial hypertrophy, heart failure, hypertension, diabetes vessel diseases and so on, the activity of NHE in myocardial and vascular smooth muscles were increased and NHE inhibitor could decline the cell proliferation.Because the proliferation of VSMCs is the mainly pathophysiological change in restenosis after PTCA, we hypothesize that inhibition of NHE may be effective in prevention of restenosis after PTCA.Objective The aim of current study was to examine the change of NHE-1 protein quantity in iliac artery smooth muscle after balloon injuries and the effectiveness of the NHE inhibitor Amiloride in vessel stenosis in rabbits.Methods 22 adult male New Zealand white rabbits were randomly divided into intervention group (IG), with 12 rabbits, and control group (CG), with 10 rabbits. Each group was divided into left-side arterial injury group and right-side arterial injury group equally. Using a 2.5mm X 20mm Foley's tube to injury one side iliac artery as operation side (OS) and another side was used as pseudo- operation side (PS) which was put a same Foley's tube into the vessel but without injuries. 3 days before balloon injuries, Amiloride (5mg/kg-d) were injected intraperitoneally, 3 times per day in IG and the same dosage NS were used in the same way in CG till 28 days after operation. Then the rabbits were killed and the iliac arteries were taken out, fixed, embed, sectioned and (1) stained with Hematoxylin and Eosin to observe the morphologic changes of the vessel cava, neointima and the media layer under the microscope; (2) parts of the smooth muscles from CG were brought out to test NHE-1 protein quantity using western blotting; (3) stained with a -actin immunohistochemistry staining to observe the VSMCs migration into the neointima and (4) stained with Masson's trichrome staining to observe the ECMs in the vessel wall. The data were in MEAN+ SD ( x+s) and statistics analysis was made using SPSS 10.0 software.Results1 Morphological change: 4 weeks after...
|
PDF Full Text Request