The Function Of Perivascular Adipose Tissue On Vascular Remodeling In Renovascular Hypertension

Chaper1Establishment of two kidney one clip renovascular hypertensive rat modelBACKGROUNDHypertension is a common disease. It is a major problem of public health in worldwide. High blood pressure can cause many organs’diseases. Of all these diseases, stroke and myocardial infarction are the most common. So theses two become the risk factors of human disability or death. For a long time, many scholars dedicated to animal models of hypertension. The establishment of appropriate animal models is an important tool of researching pathogenesis, treatment and prevention of diseases.Two kidney one clip is a classical method of establishment of hypertension. This model is simple, high success rate and wide range of application. Such method can be applied to many animals, including rats, mice, rabbits, dogs, pigs, monkeys and other. Renal hypertension has a considerable proportion in the pathogenesis of hypertension. The establishment of hypertensive animal model of renal artery stenosis lay the foundation for the clinical study of hypertensive pathogenesis, drug research and development. This experiment is to use silver needle and suture to establish two kidney one clip renovascular hypertensive rat model.METHODS30SD rats were randomly divided equally into sham group and renovascular hypertension group. Renovascular hypertensive rat model was constructed through two kidney one clip technique. This model used silver needle and suture to establish revovascular hypertension. All rats were evaluated blood pressure before operation and after operation.RESULTSAfter the renal arterial constriction, all rats developed hypertension in7days. Hypertension has been initially formed after14days. After21days hypertension has been stabilized and continued at a high level. Compared to sham group, systolic blood pressure and diastolic blood pressure in renovascular hypertension group were all increased (P<0.05). The success rate was86.7%.CONCLUSIONIt’s appropriate to use silver needle and suture to establish two kidney one clip renovascular hypertensive rat model in general laboratory’. This method conform the needs of hypertensive experimental researches. Chapter2The function of perivascular adipose tissue in renovascular hypertensionBACKGROUNDPerivascular adipose tissue (PVAT) surrounds blood vessels, which is composed of adipose cells. The research of PVAT is often linked with the metabolic syndrome. The amount of fat increase or decrease in PVAT will cause the function of PVAT to change, causing type2diabetes or hypertension. Studies have found that the amount of PVAT in Spontaneously hypertensive rat (SHR) is equal to or less than that of its normotensive control, Wistar-Kyoto rats (WKY). Morphologically, adipocytes from SHR PVAT have smaller size than that from WKY. PVAT modulates vessel function not only in the conduit artery aorta, but also in small arteries, which contribute more to peripheral resistance than conduit arteries. PVAT is closely linked with hypertension.It is not yet clear that altered PVAT function is a causative factor or a consequence of hypertension.And further studies need to explore if PVAT fat cell changes on function and morphology are consistent with high blood pressure level. PVAT plays a role on artery vascular tone. And we speculate that PVAT may be take change in morphology or function in the early hypertension. The dynamic equilibrium is broken, causing increased vascular tone and blood pressure is raised. In this study, renal hypertension rat mode was constructed through two kidney one clip (2K1C) technique. We tested PVAT morphological and functional changes to investigate the roles of the PVAT in renovascular hypertension for the further research of PVAT and hypertension.METHOUDSRenovascular hypertensive rat model was constructed through2K1C technique.20SD rats were randomly divided equally into sham group (SH) and renovascular hypertension group (RH). Contraction of aorta with PVAT or without PVAT from the2groups of rats in response to phenylephrine (PHE) and acetylcholine (Ach) was tested after8weeks model construction. The expression of NOS was assayed by immunohistochemistry. All rats were evaluated blood pressure, heart rate (HR), microscopic changes in adipose cells and vascular structure and intima media thickness (MT), lumen diameter (LD) and ratio of media thickness to lumen diameter(MT/LD) of thoracic aorta.RESULTS Contraction of aorta from the2groups of rats in response to PHE was significantly attenuated by the presence of PVAT(P<0.05). Relaxation of aorta from SH group in response to Ach (10-5and10-4mo1/L) was significantly increased in the presence of PVAT. Compared with SH group, relaxation in RH group showed significant increase in response to Ach (10-4mo1/L) in the presence of PVAT(P<0.05). NOS expression in aorta was higher in SH group than in RH group. Microscopic changes in adipose cells and vascular structure were no significantly different.CONCLUSIONPVAT could regulate the relaxation and contraction of the blood. The function of this regulation was reduced in the RH. PVAT could be a new target for treating hypertension. Chapter3The function of perivascular adipose tissue on vascular remolding in renovascular hypertensionBACKGROUNDWith the study of hypertension, the development of hypertension and its complications are closely related to vascular remodeling. Type of vascular remodeling, characteristics and mechanism in the hypertensive process are one of the hot points in the high blood pressure research field. PVAT may play a role in maintaining vascular structure, because many substances produced by PVAT affect smooth muscle proliferation and migration.The renin-angiotensin system (RAS) is an important system in maintaining blood pressure, body water and electrolyte balance. Ang Ⅱ is an important biologically active substance in the RAS, which is the product of a series of enzymatic biochemical reactions. In addition to the circulating RAS, local organizations such as the heart, vascular wall, brain, kidney, effectively generated Ang Ⅱ, are independent local RAS system. PVAT is a local RAS. The fat cells in PVAT are rich source of angiotensinogen and have all the enzymes to produce AngⅡ. The first part of our study confirmed that PVAT was related with the occurrence and development of hypertension. Therefore, PVAT may be involved in vascular remodeling of hypertension through RAS. In the present study, we observed the expression of the relevant components of the RAS with vascular remodeling correlation in PVAT of hypertensive rat. METHODS Renovascular hypertension rat mode was constructed through two kidney one clip (2K1C) technique.30SD rats were randomly divided equally into sham group (SH) and renovascular hypertension group (RH). All rats were evaluated caudal blood pressure, heart rate (HR) after12weeks. The level of Ang Ⅱ was measured by radioimmunoassay. The expression of AGT and ACE were tested by Real-time quantitative PCR. Using western blot detected protein expression of AT1and AT2. H2O2was also detected in PVAT.RESULTSAfter12weeks of operation, the aortic remolding was discovered in RH group. The level of Ang Ⅱ、 expression of AGT、 ACE、 AT1and H2O2were all higher in RH group than jin SH group. But the protein expression of AT2was equal between in the two groups.CONCLUSIONIn renovascular hypertension, PVAT is related with vascular remolding. ROS may be one of the factors in the mechanism of vascular remolding induced by PVAT. Chaper4The mechanism of VSMCs proliferation induced by Ang Ⅱ in perivascular adipose tissueBACKGROUNDOur previous study found that the PVAT associated with the vascular remodeling under pathological state of renovascular hypertension.However, the mechanisms responsible for the effect of PVAT on vascular remodeling remain unknown. NAD(P)H oxidase enzyme ia the major sourse of ROS and plays an important role in oxidative stress-mediated vascular smooth muscle cells (VSMCs) proliferation, migration in the pathogenesis of vascular remodeling. Extracellular signal-regulated kinasel/2(ERK1/2) signaling pathway is one of the important pathways.PVAT are source of vascular superoxide and the main enzyme for superoxide production is NAD (P) H oxidase. Ang Ⅱ is a known stimulator of NAD (P) H oxidase to produce ROS. Researches have shown that HOCL could activate the ERK1/2phosphorylation to induce vascular VSMCs migration. Therefore, in the present study, we use vascular smooth muscle cells, detecting H2O2, HOCL and indicators expression of proliferation of VSMCs to investigate the mechanisms of VSMCs proliferation and migration induced by Ang Ⅱ in PVAT.METHODSRat aortic smooth muscle cells were cultured. Smooth muscle cellular proliferatial rate was determined by MTT assay. ROS, H2O2and HOCL were detected after the treatment of Ang Ⅱ. NADPH inhibitor (apocynin), H2O2enzymes (catalase), ERK1/2inhibitor (PD98059) were treated respectively before the Ang Ⅱ treatment on cells. Then the total cellular protein, cell cycle, the content of H2O2and HOCL were tested.RESULTSAfter treatment of100nM Ang Ⅱ24h, cells proliferated and ROS increased compared with the normal group. NADPH inhibitor (apocynin), H2O2enzymes (catalase) and ERK1/2inhibitor (PD98059) inhibited cell proliferation. And NADPH inhibitor (apocynin) and H2O2enzymes (catalase) reduced the level of H2O2and HOCL. But the ERK1/2inhibitor (PD98059) had no such effect.CONCLUSIONIn PVAT, the way of ROS in mediating the proliferation of VSMCs induced by Ang Ⅱ may be Nox/H2O2/HOCL/ERK1/2.