The protective effects of Astragaloside Ⅳ on diastolic function of rat thoracic aortic rings impaired by microvesicles / 中国应用生理学杂志

OBJECTIVES@#To investigate the effects of Astragaloside IV (AST) on diastolic function of rat thoracic aorta rings which was injured by microvesicles derived from hypoxia/reoxygenation (H/R)-treated human umbilical vein endothelial cells (HUVECs), and the mechanism of AST.@*METHODS@#H/R-induced endothelial microvesicles (H/R-EMVs) were generated from cultured HUVECs under the condition of hypoxia for 12 hour/Reoxygenation for 4 hour, H/R-EMVs were stored in D-Hank's solution. Male Wistar rats were underwent thoracotomy, the thoracic aorta with intact endothelium were carefully removed and cut into 3~4 mm rings. The experiment was divided into six groups. H/R-EMVs group:thoracic aortic rings of rats were incubated in culture medium and treated with H/R-EMVs in a final concentration of 10g/ml; different doses of AST groups:thoracic aortic rings of rats were treated with 10, 20, 40, 60 mg/L AST co-incubated with 10g/ml H/R-EMVs respectively; control group were treated with the same volume of D-Hank's solution. Duration of incubation was 4 h, each group was tested in five replicate aortic rings. Effects of AST on endothelium-dependent relaxation were detected. The production of nitric oxide (NO) and the level of endothelial NO synthase (eNOS), phosphorylated eNOS (p-eNOS, Ser-1177), serine/threonine kinase (Akt), phosphorylated Akt (p-Akt, Ser-473), extracellular regulated protein kinases (ERK1/2) and phosphorylated ERK1/2 (p-ERK1/2, Thr202/Tyr204) of rat thoracic aortic rings were detected.@*RESULTS@#Teng/ml H/R-EMVs could impaire the relaxation of rat thoracic aortic rings significantly (<0.01). Compared with H/R-EMVs group, relaxation of rat thoracic aortic rings was increased by 20, 40 and 60 mg/L AST in a concentration-dependent manner (<0.01), the level of NO production was also enhanced (<0.05, <0.01). The level of t-eNOS, t-Akt and ERK1/2 was not changed, but the level of p-eNOS, p-Akt and p-ERK1/2 increased by the treatment with AST (<0.01).@*CONCLUSIONS@#AST could effectively ameliorate endotheliumdependent relaxation of rat thoracic aortic rings impaired by H/R-EMVs in a concentration-dependent manner, the mechanism might involve the increase in production of NO, and the protein level of p-eNOS, p-Akt and p-ERK1/2.

[Iptakalim ameliorates relaxation to acetylcholine in thoracic aortic rings impaired by microvesicles derived from hypoxia/reoxygenation-treated HUVECs].

OBJECTIVE: To investigate the effect of Iptakalim (Ipt) preventing injury of endothelial microvesicles (EMVs) derived from hypoxia/reoxygenation (H/R)-treated HUVECs on the relaxation of rat thoracic aortic rings and explore the underlying mechanism. METHODS: H/R injury model was established to release H/R-EMVs from HUVECs. H/R-EMVs from HUVECs were isolated by ultracentrifugation from the conditioned culture medium. H/R-EMVs were characterized by using Transmission Electron Microscope (TEM). Thoracic aortic rings of rats were incubated with 10-7-10-3 mol/L Ipt and co-cultured with 10 µg/ml H/R-EMVs for 4 hours, and their endothelium-dependent relaxation in response to acetylcholine (ACh) was recorded in vitro. The nitric oxide (NO) production of ACh-treated rat thoracic aortic rings was measured by using Griess reagent. The expression of endothelial NO synthase (eNOS), phosphorylated eNOS (p-eNOS, Ser-1177), serine/threonine kinas (Akt) and phosphorylated Akt (p-Akt, Ser-473) in the thoracic aortic rings of rats was detected by Western blotting. RESULTS: H/R-EMVs were induced by H/R-treated HUVECs and isolated by ultracentrifugation. The isolated H/R-EMVs subjected to TEM revealed small, rounded vesicles (100-1 000 nm) surrounded by a membrane. H/R-EMVs impaired relaxation induced by ACh of rat thoracic aortic rings significantly. Compared with H/R-EMVs treatment individually, relaxation and NO production of rat thoracic aortic rings were increased by Ipt treatment in a concentration-dependent manner (P<0.05, P<0.01). The expression of total eNOS (t-eNOS) and total Akt (t-Akt) was not affected by Ipt or H/R-EMVs. However, the expression of p-eNOS and p-Akt increased after treated with Ipt (P<0.01). CONCLUSIONS: Based on H/R-EMVs treatment, ACh induced endothelium-dependent relaxation of rat thoracic aortic rings was ameliorated by Ipt in a concentration-dependent manner. The mechanisms involved the increase in NO production, p-eNOS and p-Akt expression.

Flow cytometric analysis of circulating microvesicles derived from myocardial Ischemic preconditioning and cardioprotection of Ischemia/reperfusion Injury in rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To establish a flow cytometric method to detect the alteration of phenotypes and concentration of circulating microvesicles (MVs) from myocardial ischemic preconditioning (IPC) treated rats (IPC-MVs), and to investigate the effects of IPC-MVs on ischemia/reperfusion (I/R) injury in rats.</p><p><b>METHODS</b>Myocardial IPC was elicited by three.cycles of 5-min ischemia and 5-min reperfusion of the left anterior descending (LAD) coronary artery. Platelet-free plasma (PFP) was isolated through two steps of centrifugation at room temperature from the peripheral blood, and IPC-MVs were isolated by ultracentrifugation from PFR PFP was incubated with anti-CD61, anti-CD144, anti-CD45 and anti-Erythroid Cells, and added 1, 2 µm latex beads to calibrate and absolutely count by flow cytometry. For functional research, I/R injury was induced by 30-min ischemia and 120-min reperfusion of LAD. IPC-MVs 7 mg/kg were infused via the femoral vein in myocardial I/R injured rats. Mean arterial blood pressure (MAP), heart rate (HR) and ST-segment of electro-cardiogram (ECG) were monitored throughout the experiment. Changes of myocardial morphology were observed after hematoxylin-eosin (HE) staining. The activity of plasma lactate dehydrogenase (LDH) was tested by Microplate Reader. Myocardial infarct size was measured by TTC staining.</p><p><b>RESULTS</b>Total IPC-MVs and different phenotypes, including platelet-derived MVs (PMVs), endothelial cell-derived MVs (EMVs), leucocyte-derived MVs (LMVs) and erythrocyte-derived MVs (RMVs) were all isolated which were identified membrane vesicles (<1 Vm) with corresponding antibody positive. The numbers of PMVs, EMVs and RMVs were significantly increased in circulation of IPC treated rats (P<0.05, respectively). In addition, at the end of 120-min reperfusion in I/R injured rats, IPC-MVs markedly increased HR (P<0.01), decreased ST-segment and LDH activity (P < 0.05, P < 0.01). The damage of myocardium was obviously alleviated and myocardial infarct size was significantly lowered after IPC-MVs treatment (P < 0.01).</p><p><b>CONCLUSION</b>The method of flow cytometry was successfully established to detect the phenotypes and concentration alteration of IPC-MVs, including PMVs, EMVs, LMVs and RMVs. Furthermore, circulating IPC-MVs protected myocardium against I/R injury in rats.</p>