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
This review synthesizes the methods for estimating the distribution coefficient (K<sub>d</sub>) and provides a compilation of K<sub>d</sub> values for five heavy metals (As, Pb, Cd, Cu, and Zn)...This review synthesizes the methods for estimating the distribution coefficient (K<sub>d</sub>) and provides a compilation of K<sub>d</sub> values for five heavy metals (As, Pb, Cd, Cu, and Zn) based on research published in the last decade (2012-2021). We used the PRISMA method to ensure the transparency of the collected data. For mono-metal systems (MS), the K<sub>d</sub> values ranged from 10<sup>-</sup><sup>2</sup> to 10<sup>7</sup> L/kg for Pb, from 10<sup>-</sup><sup>2</sup> to 10<sup>6</sup> L/kg for Cd, As, and Zn, and from 10<sup>-</sup>2 to 10<sup>5</sup> L/kg for Cu. In competitive systems (CS), the K<sub>d</sub> values ranged from 10<sup>-</sup>2 to 10<sup>5</sup> L/kg for Cu, and 10<sup>-</sup>2 to 10<sup>4</sup> L/kg for Pb, Cd, and Zn, while no K<sub>d</sub> value for As was reported under CS. It was found that the K<sub>d</sub> values of heavy metals are affected not only by soil chemical and physical properties but also by the nature and characteristics of the metal involved along with experimental conditions. The totals references number of K<sub>d</sub> data observation per element metal are represented as follows: Cd 35 (50%), Zn 35 (50%), Pb 33 (47.14%), Cu 33 (47.14%), and As 19 (27.14%). Overall, most research was done 1) on MS rather than CS, 2) on sorption rather than desorption, 3) on soil rather than sediments , and 4) most literature have reported the K<sub>d</sub> values, derived from batch method than on column method. Despite significant progress over the past decade towards a better understanding of the variation in K<sub>d</sub> values and the effect of factors influencing them to provide important parameters for predicting and controlling toxic metals in soils, additional research is still warranted to the complexity of underlying processes.展开更多
通过碱性甲醇溶液超声提取,结合杏仁来源β-葡萄糖苷酶水解及聚酰胺分散式固相萃取步骤,建立了超高效液相色谱测定大豆异黄酮活性总量的方法。样品中的丙二酰及乙酰类大豆异黄酮苷在碱性条件下水解成基本型苷,并在β-葡萄糖苷酶的作用...通过碱性甲醇溶液超声提取,结合杏仁来源β-葡萄糖苷酶水解及聚酰胺分散式固相萃取步骤,建立了超高效液相色谱测定大豆异黄酮活性总量的方法。样品中的丙二酰及乙酰类大豆异黄酮苷在碱性条件下水解成基本型苷,并在β-葡萄糖苷酶的作用下进一步脱去糖基转变为相应的苷元。样品中12种不同形式的大豆异黄酮转变为仅含3种大豆异黄酮苷元(大豆苷元、黄豆黄素、染料木素)后,以聚酰胺粉进行分散式固相萃取,C_(18)反相色谱柱(2.1 mm i.d.×50 mm,1.8μm)分离。结果显示,大豆苷元、黄豆黄素及染料木素在3 min内实现基线分离,3种异黄酮苷元的标准曲线相关系数(r^(2))均大于0.999,总异黄酮的回收率为94.3%~102%,相对标准偏差(RSD,n=6)小于5.0%,具有较高的准确度和精密度。该方法通过检测样品中的全部苷元来计算异黄酮总量,有助于降低异黄酮检测在分离度、准确度及检测成本上带来的挑战;考虑异黄酮在体内的转化吸收机制和生理效应,以苷元总量计能更科学地反映实际的异黄酮活性水平,避免因通过苷和苷元的简单加和而造成对异黄酮含量水平的高估。展开更多
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.
文摘This review synthesizes the methods for estimating the distribution coefficient (K<sub>d</sub>) and provides a compilation of K<sub>d</sub> values for five heavy metals (As, Pb, Cd, Cu, and Zn) based on research published in the last decade (2012-2021). We used the PRISMA method to ensure the transparency of the collected data. For mono-metal systems (MS), the K<sub>d</sub> values ranged from 10<sup>-</sup><sup>2</sup> to 10<sup>7</sup> L/kg for Pb, from 10<sup>-</sup><sup>2</sup> to 10<sup>6</sup> L/kg for Cd, As, and Zn, and from 10<sup>-</sup>2 to 10<sup>5</sup> L/kg for Cu. In competitive systems (CS), the K<sub>d</sub> values ranged from 10<sup>-</sup>2 to 10<sup>5</sup> L/kg for Cu, and 10<sup>-</sup>2 to 10<sup>4</sup> L/kg for Pb, Cd, and Zn, while no K<sub>d</sub> value for As was reported under CS. It was found that the K<sub>d</sub> values of heavy metals are affected not only by soil chemical and physical properties but also by the nature and characteristics of the metal involved along with experimental conditions. The totals references number of K<sub>d</sub> data observation per element metal are represented as follows: Cd 35 (50%), Zn 35 (50%), Pb 33 (47.14%), Cu 33 (47.14%), and As 19 (27.14%). Overall, most research was done 1) on MS rather than CS, 2) on sorption rather than desorption, 3) on soil rather than sediments , and 4) most literature have reported the K<sub>d</sub> values, derived from batch method than on column method. Despite significant progress over the past decade towards a better understanding of the variation in K<sub>d</sub> values and the effect of factors influencing them to provide important parameters for predicting and controlling toxic metals in soils, additional research is still warranted to the complexity of underlying processes.
文摘通过碱性甲醇溶液超声提取,结合杏仁来源β-葡萄糖苷酶水解及聚酰胺分散式固相萃取步骤,建立了超高效液相色谱测定大豆异黄酮活性总量的方法。样品中的丙二酰及乙酰类大豆异黄酮苷在碱性条件下水解成基本型苷,并在β-葡萄糖苷酶的作用下进一步脱去糖基转变为相应的苷元。样品中12种不同形式的大豆异黄酮转变为仅含3种大豆异黄酮苷元(大豆苷元、黄豆黄素、染料木素)后,以聚酰胺粉进行分散式固相萃取,C_(18)反相色谱柱(2.1 mm i.d.×50 mm,1.8μm)分离。结果显示,大豆苷元、黄豆黄素及染料木素在3 min内实现基线分离,3种异黄酮苷元的标准曲线相关系数(r^(2))均大于0.999,总异黄酮的回收率为94.3%~102%,相对标准偏差(RSD,n=6)小于5.0%,具有较高的准确度和精密度。该方法通过检测样品中的全部苷元来计算异黄酮总量,有助于降低异黄酮检测在分离度、准确度及检测成本上带来的挑战;考虑异黄酮在体内的转化吸收机制和生理效应,以苷元总量计能更科学地反映实际的异黄酮活性水平,避免因通过苷和苷元的简单加和而造成对异黄酮含量水平的高估。
