Angiotensin II (Ang II) is the main mediator of the Renin-Angiotensin-System acting on AT<sub>1</sub> and other AT receptors. It is regarded as a pleiotropic agent that induces many actions, including func...Angiotensin II (Ang II) is the main mediator of the Renin-Angiotensin-System acting on AT<sub>1</sub> and other AT receptors. It is regarded as a pleiotropic agent that induces many actions, including functioning as a growth factor, and as a contractile hormone, among others. The aim of this work was to examine the impact of Ang II on the expression and function of α<sub>1</sub>-adrenergic receptors (α<sub>1</sub>-ARs) in cultured rat aorta, and aorta-derived smooth muscle cells. Isolated Wistar rat aorta was incubated for 24 h in DMEM at 37˚C, then subjected to isometric tension and to the action of added norepinephrine, in concentration-response curves. Ang II was added (1 × 10<sup>−5</sup> M), and in some experiments, 5-Methylurapidil (α<sub>1A</sub>-AR antagonist), AH11110A (α<sub>1B</sub>-AR antagonist), or BMY-7378 (α<sub>1D</sub>-AR antagonist), were used to identify the α<sub>1</sub>-AR involved in the response. Desensitization of the contractile response to norepinephrine was observed due to incubation time, and by the Ang II action. α<sub>1D</sub>-AR was protected from desensitization by BMY-7378;while RS-100329 and prazosin partially mitigated desensitization. In another set of experiments, isolated aorta-derived smooth muscle cells were exposed to Ang II and α<sub>1</sub>-ARs proteins were evaluated. α<sub>1D</sub>-AR increased at 30 and 60 min post Ang II exposure, the α<sub>1A</sub>-AR diminished from 1 to 4 h, while α<sub>1B</sub>-AR remained unchanged over 24 h of Ang II exposure. Ang II induced an increase of α<sub>1D</sub>-AR at short times, and BMY-7378 protected α<sub>1D</sub>-AR from desensitization.展开更多
Desensitization is a process characterized by the loss of cellular response to an agonist when this is present for a long time. α<sub>1D</sub>-adrenergic receptor (α<sub>1D</sub>-AR) desensit...Desensitization is a process characterized by the loss of cellular response to an agonist when this is present for a long time. α<sub>1D</sub>-adrenergic receptor (α<sub>1D</sub>-AR) desensitization is important since this receptor is involved in the contraction of large caliber arteries, such as the aorta. The aim of this research was to evaluate the desensitization of α<sub>1D</sub>-AR due to the endogenous release of norepinephrine in cultured rat aorta. Wistar rat aorta was incubated for 2 h or 24 h in DMEM at 37°C, and then subjected to isometric tension and the action of added norepinephrine, in concentration-response curve (CRC). In some experiments, BMY-7378 (α<sub>1D</sub>-AR antagonist) or 5-methylurapidil (α<sub>1A</sub>-AR antagonist) was used to identify the α<sub>1</sub>-AR involved in the response, or BMY-7378 to protect the α<sub>1D</sub>-AR from desensitization. Results showed that α<sub>1D</sub>-AR was desensitized when the aorta was incubated for 24 h, since the CRC to exogenous norepinephrine showed lower maximal contraction and the curve was displaced to the right, indicating that the receptor involved in contraction was not the α<sub>1D</sub>-AR, as compared to the aorta incubated 2 h. The receptor stimulated by norepinephrine at 24 h was neither the α<sub>1A</sub>-AR, as shown by the lack of displacement of the curve by 5-methylurapidil, but rather it seems that α<sub>1B</sub>-AR is inducing contraction. When the aorta was incubated with BMY-7378 for 24 h, the α<sub>1D</sub>-AR antagonist protected the receptor from desensitization. Endogenous norepinephrine desensitizes α<sub>1D</sub>-AR in the cultured aorta, and the α<sub>1D</sub>-AR is protected by BMY-7378.展开更多
Methoxyl methyl ether isoamylene quercetin （MIAQ） is one of the newly synthesized quercetin derivatives. The present study investigated the effect of MIAQ on rat aorta endothelial cells （RAECs） injured by hydrogen...Methoxyl methyl ether isoamylene quercetin （MIAQ） is one of the newly synthesized quercetin derivatives. The present study investigated the effect of MIAQ on rat aorta endothelial cells （RAECs） injured by hydrogen peroxide （H2O2）, as well as the potential mechanisms. We observed that MIAQ at 2.5-10μmol/L significantly enhanced the viability of injured RAECs, and the effect was more potent than quercetin and ct-tocopherol. However, M1AQ at the same concentration failed to show anti-oxidant activity in a cell-free system. In H2O2-injured endothelial cells treated with MIAQ （5-10μmol/L）, the level of nitric oxide （NO） and malondialdehyde was decreased, and the activities of superoxide dismutase and glutathione peroxidase was enhanced. In addition, RAECs treated with MIAQ （2.5-10 μmol/L） exhibited significant inhibiting apoptosis. In conclusion, MIAQ had protective effect on RAECs, possibly through increasing NO production and antioxidases activities, as well as inhibiting apoptosis. These findings suggest that MIAQ is possibly beneficial in the prevention of atherosclerosis and other diseases related to endothelial injury.展开更多
Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contract...Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contractions. Recently, it was suggested that repeated stimulation with clonidine induces desensitization of α2-ARs, thus inhibiting noradrenaline-induced smooth muscle contractions. In the present study, we examined whether clonidine-mediated inhibition of α1-AR contractions involves interactions with α2-ARs in rat thoracic aortae. 1) Clonidine and guanfacine inhibited electrical field stimulation-induced contractions in a concentration-dependent, yohimbine-sensitive manner in isolated rat vas deferens preparations. 2) Clonidine almost completely suppressed phenylephrine-induced sustained contractions of rat thoracic aortae. 3) Clonidine competitively inhibited phenylephrine-induced contractions with a pA2 value of 6.77 at concentrations between 10-7 and 10-6 M. At 10-5 M, clonidine inhibited phenylephrine-induced contractions and dramatically reduced maximum contractions. 4) In contrast, clonidine did not inhibit contractions produced by high KCl or prostaglandin F2α. 5) Inhibition of phenylephrine-induced sustained contractions by clonidine was also produced in the presence of yohimbine. However, guanfacine did not inhibit phenylephrine-induced sustained contractions. These findings suggest that clonidine inhibits phenylephrine-induced contraction of rat thoracic aortae by competitive antagonism of α1-ARs, which is mediated through a mechanism independent of α2-AR stimulation.展开更多
目的探讨沉默信息调节因子2相关酶1(silent mating type information regulation 2 homolog-1,SIRT1)抑制剂EX-527与激动剂SRT1720对老化内皮细胞成血管能力的影响。方法采用体外培养大鼠原代主动脉内皮细胞衰老技术,通过培养细胞的自...目的探讨沉默信息调节因子2相关酶1(silent mating type information regulation 2 homolog-1,SIRT1)抑制剂EX-527与激动剂SRT1720对老化内皮细胞成血管能力的影响。方法采用体外培养大鼠原代主动脉内皮细胞衰老技术,通过培养细胞的自然倍增建立大鼠主动脉内皮细胞(rat aorta endothelial cell,RAEC)衰老的细胞模型。内皮细胞的衰老用SA-β-Gal染色进行鉴定。衰老细胞模型建立后,对衰老的RAEC分别给予SIRT1抑制剂EX527和SIRT1激动剂SRT1720干预。运用Ki-67免疫荧光染色检测内皮细胞增殖,采用基质胶内皮管形成实验检测内皮细胞内皮管形成,应用蛋白印迹技术检测内皮细胞eNOS表达。结果SIRT1激动剂抑制老化RAEC增殖能力、内皮管形成能力和eNOS表达的降低,而SIRT1抑制剂使老化RAEC的增殖能力、内皮管形成能力和eNOS表达降低。结论SIRT1促进RAEC的增殖和内皮管形成,并增强RAEC中eNOS的表达;SIRT1改善衰老内皮细胞受损的成血管能力可能与其抑制衰老RAEC eNOS表达的下调有关。展开更多
Male Wistar rats were used to study the changes of the structure and architecture of the smooth muscle cells(SMCs) of the aorta under pressure overloading(PO).The aorta was cut open longitudinally and the tunica media...Male Wistar rats were used to study the changes of the structure and architecture of the smooth muscle cells(SMCs) of the aorta under pressure overloading(PO).The aorta was cut open longitudinally and the tunica media was examined with a histological tech展开更多
文摘Angiotensin II (Ang II) is the main mediator of the Renin-Angiotensin-System acting on AT<sub>1</sub> and other AT receptors. It is regarded as a pleiotropic agent that induces many actions, including functioning as a growth factor, and as a contractile hormone, among others. The aim of this work was to examine the impact of Ang II on the expression and function of α<sub>1</sub>-adrenergic receptors (α<sub>1</sub>-ARs) in cultured rat aorta, and aorta-derived smooth muscle cells. Isolated Wistar rat aorta was incubated for 24 h in DMEM at 37˚C, then subjected to isometric tension and to the action of added norepinephrine, in concentration-response curves. Ang II was added (1 × 10<sup>−5</sup> M), and in some experiments, 5-Methylurapidil (α<sub>1A</sub>-AR antagonist), AH11110A (α<sub>1B</sub>-AR antagonist), or BMY-7378 (α<sub>1D</sub>-AR antagonist), were used to identify the α<sub>1</sub>-AR involved in the response. Desensitization of the contractile response to norepinephrine was observed due to incubation time, and by the Ang II action. α<sub>1D</sub>-AR was protected from desensitization by BMY-7378;while RS-100329 and prazosin partially mitigated desensitization. In another set of experiments, isolated aorta-derived smooth muscle cells were exposed to Ang II and α<sub>1</sub>-ARs proteins were evaluated. α<sub>1D</sub>-AR increased at 30 and 60 min post Ang II exposure, the α<sub>1A</sub>-AR diminished from 1 to 4 h, while α<sub>1B</sub>-AR remained unchanged over 24 h of Ang II exposure. Ang II induced an increase of α<sub>1D</sub>-AR at short times, and BMY-7378 protected α<sub>1D</sub>-AR from desensitization.
文摘Desensitization is a process characterized by the loss of cellular response to an agonist when this is present for a long time. α<sub>1D</sub>-adrenergic receptor (α<sub>1D</sub>-AR) desensitization is important since this receptor is involved in the contraction of large caliber arteries, such as the aorta. The aim of this research was to evaluate the desensitization of α<sub>1D</sub>-AR due to the endogenous release of norepinephrine in cultured rat aorta. Wistar rat aorta was incubated for 2 h or 24 h in DMEM at 37°C, and then subjected to isometric tension and the action of added norepinephrine, in concentration-response curve (CRC). In some experiments, BMY-7378 (α<sub>1D</sub>-AR antagonist) or 5-methylurapidil (α<sub>1A</sub>-AR antagonist) was used to identify the α<sub>1</sub>-AR involved in the response, or BMY-7378 to protect the α<sub>1D</sub>-AR from desensitization. Results showed that α<sub>1D</sub>-AR was desensitized when the aorta was incubated for 24 h, since the CRC to exogenous norepinephrine showed lower maximal contraction and the curve was displaced to the right, indicating that the receptor involved in contraction was not the α<sub>1D</sub>-AR, as compared to the aorta incubated 2 h. The receptor stimulated by norepinephrine at 24 h was neither the α<sub>1A</sub>-AR, as shown by the lack of displacement of the curve by 5-methylurapidil, but rather it seems that α<sub>1B</sub>-AR is inducing contraction. When the aorta was incubated with BMY-7378 for 24 h, the α<sub>1D</sub>-AR antagonist protected the receptor from desensitization. Endogenous norepinephrine desensitizes α<sub>1D</sub>-AR in the cultured aorta, and the α<sub>1D</sub>-AR is protected by BMY-7378.
基金National Natural Science Foundation of China (Grant No. 61071002)
文摘Methoxyl methyl ether isoamylene quercetin （MIAQ） is one of the newly synthesized quercetin derivatives. The present study investigated the effect of MIAQ on rat aorta endothelial cells （RAECs） injured by hydrogen peroxide （H2O2）, as well as the potential mechanisms. We observed that MIAQ at 2.5-10μmol/L significantly enhanced the viability of injured RAECs, and the effect was more potent than quercetin and ct-tocopherol. However, M1AQ at the same concentration failed to show anti-oxidant activity in a cell-free system. In H2O2-injured endothelial cells treated with MIAQ （5-10μmol/L）, the level of nitric oxide （NO） and malondialdehyde was decreased, and the activities of superoxide dismutase and glutathione peroxidase was enhanced. In addition, RAECs treated with MIAQ （2.5-10 μmol/L） exhibited significant inhibiting apoptosis. In conclusion, MIAQ had protective effect on RAECs, possibly through increasing NO production and antioxidases activities, as well as inhibiting apoptosis. These findings suggest that MIAQ is possibly beneficial in the prevention of atherosclerosis and other diseases related to endothelial injury.
文摘Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contractions. Recently, it was suggested that repeated stimulation with clonidine induces desensitization of α2-ARs, thus inhibiting noradrenaline-induced smooth muscle contractions. In the present study, we examined whether clonidine-mediated inhibition of α1-AR contractions involves interactions with α2-ARs in rat thoracic aortae. 1) Clonidine and guanfacine inhibited electrical field stimulation-induced contractions in a concentration-dependent, yohimbine-sensitive manner in isolated rat vas deferens preparations. 2) Clonidine almost completely suppressed phenylephrine-induced sustained contractions of rat thoracic aortae. 3) Clonidine competitively inhibited phenylephrine-induced contractions with a pA2 value of 6.77 at concentrations between 10-7 and 10-6 M. At 10-5 M, clonidine inhibited phenylephrine-induced contractions and dramatically reduced maximum contractions. 4) In contrast, clonidine did not inhibit contractions produced by high KCl or prostaglandin F2α. 5) Inhibition of phenylephrine-induced sustained contractions by clonidine was also produced in the presence of yohimbine. However, guanfacine did not inhibit phenylephrine-induced sustained contractions. These findings suggest that clonidine inhibits phenylephrine-induced contraction of rat thoracic aortae by competitive antagonism of α1-ARs, which is mediated through a mechanism independent of α2-AR stimulation.
文摘Male Wistar rats were used to study the changes of the structure and architecture of the smooth muscle cells(SMCs) of the aorta under pressure overloading(PO).The aorta was cut open longitudinally and the tunica media was examined with a histological tech
