To investigate the effect of endothelin receptors in chronic venous insufficiency (CVI) in lower extremities.Ten cases of varicose veins from CVI patients (as case group) and ten cases of non-varicose veins (as control group) were investigated in this study. The two groups were divided into two groups respectively: endothelium-intact group and de-endothelium groups. The vasoconstriction mediated by endothelin A (ETA) and endothelin B (ETB) receptors was recorded with myography. The distribution of ETA and ETB receptors was detected by immunohistochemistry method.Endothelin-1 (ET-1) and sarafotoxin 6c (S6c) induced concentration-dependent contraction in the veins. In endothelium-intact veins, the E(max) and pD(2) of contraction curve induced by ET-1 were 132.30% +/- 43.42% and 6.03 +/- 0.35, respectively in control group;and were 19.24% +/- 12.94% and 6.78 +/- 0.46, respectively in case group. The E(max) and pD(2) in case group were much lower than in control group (P < 0.05). The E(max) and pD(2) induced by S6c were 30.10% +/- 12.90% and 6.54 +/- 0.36, respectively in control group, and were 9.61% +/- 1.32% and 6.75 +/- 0.29, respectively in case group; The E(max) in case group was lower than in control group (P < 0.05). In de-endothelium veins, E(max) and pD(2) of S6c were 146.18% +/- 32.33% and 6.50 +/- 0.17 in control group, and 32.93% +/- 3.00% and 6.69 +/- 0.39 in case group; The E(max) in case group was significantly lower than in control group (P < 0.05). ETA receptors was located in endothelium mainly, and ETB receptors in smooth muscle cells mainly. The sites of both ETA and ETB receptors were decreased in case group obviously.The contraction mediated by ETA receptor and ETB receptor was decreased with a decrease of ETA receptor and ETB receptor sites in varicose veins of CVI. The contraction insufficiency and down-expression of ETA receptor and ETB receptor are correlated with CVI.
Airborne fine particulate matter (PM(2.5)) increases the risk of cerebrovascular diseases. However, existing experimental data do not sufficiently explain how PM(2.5) affects cerebral vessels. This study sought to examine whether PM(2.5) alters endothelin (ET) receptor expression on rat cerebral arteries and the potential underlying mechanisms. Isolated rat basilar arteries were cultured with PM(2.5) aqueous suspension in the presence of mitogen-activated protein kinase (MAPK) pathway inhibitors. ET receptor-mediated vasomotor functions were recorded by a sensitive myograph. ET(A) and ET(B) receptor mRNA and protein expressions were assessed using quantitative real-time PCR, Western blotting, and immunohistochemistry, respectively. Compared with fresh and culture alone arteries, PM(2.5) significantly enhanced ET(A) and ET(B) receptor-mediated contractions and increased receptor mRNA and protein expressions in basilar arteries, indicating PM(2.5) upregulates ET(A) and ET(B) receptors. Culturing with SB386023 (MEK/ERK1/2 inhibitor), U0126 (ERK1/2 inhibitor), SP600125 [c-Jun N-terminal kinase (JNK) inhibitor], or SB203580 (p38 inhibitor) attenuated PM(2.5)-induced ETB receptor upregulation. PM(2.5)-induced enhancement of ET(A) receptor-mediated contraction and receptor expression was notably inhibited by SB386023 or U0126. However, neither SP600125 nor SB203580 had an effect on PM(2.5)-induced ET(A) receptor upregulation. In conclusion, PM(2.5) upregulates ET(A) and ET(B) receptors in rat basilar arteries. ET(B) receptor upregulation is involved in MEK/ERK1/2, JNK, and p38 MAPK pathways, and ET(A) receptors upregulation is associated with MEK/ERK1/2 pathway.
Abstract: This study was designed to examine the in vivo and in vitro effects of captopril, an angiotensin‐converting enzyme inhibitor, on nicotine‐induced endothelial dysfunction in rats. Endothelial dysfunction was induced by exposing isolated rat mesenteric arteries to nicotine (0.01, 0.1, or 1 mM) for 24 hr using an organ culture system, or by treating rats with nicotine (2 mg/kg/day, intraperitoneally) for 4 weeks. The protective effects of captopril were tested by exposing isolated mesenteric arteries to captopril (0.01, 0.03, or 0.1 mM) + nicotine (0.1 mM) for 24 hr, or by treating rats with captopril (3 mg/kg/day, intravenously) + nicotine (2 mg/kg/day, intraperitoneally) for 4 weeks. Exposure of the isolated mesenteric arteries to nicotine induced a significant concentration ‐dependent inhibition of endothelium‐dependent relaxation. Co‐culture of segments of mesenteric artery with captopril (0.03 or 0.1 mM) attenuated the nicotine‐induced impairment of vasorelaxation in a dose‐dependent manner. Administration of nicotine to rats for 4 weeks significantly impaired endothelium‐dependent relaxation compared with control rats. This impairment was accompanied by a reduction in nitrite/nitrate, nitric oxide (NO) synthase (NOS), and superoxide dismutase (SOD) activities in the serum and aorta. Chronic captopril treatment not only improved the impairment of endothelium‐dependent relaxation, but also prevented the reduction of nitrite/nitrate contents and of NOS and SOD activities in the serum and aorta. However, there were no significant differences in serum angiotensin‐converting enzyme activity among the three groups. These results indicate that captopril can be used to attenuate nicotine‐induced endothelial dysfunction, an effect that may be related not only to antioxidation, but also to enhancing NO production by preventing the decrease in NOS.
A simple high-performance liquid chromatography method has been developed and validated for determination of enantiomeric purity of 2-azabicyclo[2.2.1]hept-5-en-3-one with a run time of less than 10 min. Complete separation of enantiomers has been achieved on a Chiralcel OD-H analytical column (250 x 4.6 mm) using n-hexane―isopropanol (80:20, v/v) as the mobile phase at a flow rate of 1.0 mL/min under UV and optical rotation detection. The effect of the mobile phase and temperature on enantioselectivity for the enantiomers were further evaluated. The method was validated with respect to precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The recoveries were between 99.1 % and 102.2%, with percentage relative standard deviation less than 1.14%. The LOD and LOQ for the (+)-2-azabicyclo[2.2.1]hept-5-en-3-one were 1.2 and 4.3 μg/mL and for the (-)-2-azabicyclo[2.2.1]hept-5-en-3-one were 1.3 and 4.4 μg/mL, respectively. This method is expected to be helpful for the determination of the enantiomeric purity of 2-azabicyclo[2.2.1]hept-5-en-3-one in bulk samples.
Abstract Fine particulate matter (PM 2.5 ) is an important environmental risk factor for cardiovascular diseases. However, little is known about the effects of PM 2.5 on arteries. The present study investigated whether PM 2.5 alters 5‐hydroxytryptamine (5‐HT) receptor expression and inflammatory mediators on rat mesenteric arteries, and examined the underlying mechanisms. Isolated rat mesenteric arteries segments were cultured with PM 2.5 in the presence or absence of ERK1/2, JNK, and p38 pathway inhibitors. Contractile reactivity was monitored by a sensitive myograph. The expression of 5‐HT 2A/1B receptors and inflammatory mediators were studied by a real‐time polymerase chain reaction and/or by immunohistochemistry. The phosphorylation of mitogen‐activated protein kinases (MAPK) pathway was detected by Western blot. Compared with the fresh or culture alone groups, 1.0 μg/mL PM 2.5 cultured for 16 hours significantly enhanced contractile response induced by 5‐HT and increased 5‐HT 2A receptor mRNA and protein expressions, indicating PM 2.5 upregulates 5‐HT 2A receptor. SB203580 (p38 inhibitor) and U0126 (ERK1/2 inhibitor) significantly decreased PM 2.5 ‐induced elevated contraction and mRNA and protein expression of 5‐HT 2A receptor. Cultured with PM 2.5 significantly increased the mRNA expression of inflammatory mediators (NOS2, IL‐1β, and TNF‐α), while SB203580 decreased mRNA expression level of NOS2, IL‐1β, and TNF‐α. SP600125 (JNK inhibitor) decreased mRNA expression level of TNF‐α and IL‐1β. After PM 2.5 exposure, the phosphorylation of p38 and ERK1/2 protein were increased. SB203580 and U0126 inhibited the PM 2.5 caused increased phosphorylation protein of p38 and ERK1/2. In conclusion, PM 2.5 induces inflammatory‐mediated MAPK pathway in artery which subsequently results in enhanced vascular contraction responding to 5‐HT via the upregulated 5‐HT 2A receptors.
To determine the chemical structure of the new compound and investigate the protective effects of Tinosporaic acid A and B towards in-vitro neuro. The structures of two new compounds were established by analyzing its 1D and 2D NMR spectra as well as HRESIMS. Their neuroprotective effects with respect to the antioxidant properties were evaluated by radical scavenging tests and hydrogen peroxide-injured oxidative stress model in PC12 cell lines. Cell morphology of treated PC12 cells was observed by phase contrast microscopy. In-vitro MTT assay, lactate dehydrogenase activity assay and oxidative stress markers (intracellular ROS production, MDA level, and caspase-3 activity) were used to evaluate the protective effects against hydrogen peroxide induced cytotoxicity in PC12 cells. The two new compounds, named Tinosporaic acid A and B, were isolated and identified from the stem bark of Tinospora hainanensis. Cell viability studies identified a representative concentration for each extract that was subsequently used to measure oxidative stress markers. Both extracts were able to reverse the oxidative damage caused by hydrogen peroxide, thus promoting PC12 cells survival. The concentration of Tinosporaic acid A and B were 86.34 μg/mL and 22.06 μg/mL respectively, which is neuroprotective for EC50. The results indicated that both of them significantly attenuated hydrogen peroxide-induced neurotoxicity. The two new compounds isolated from ethanol extracts of Tinospora hainanensis are the promising natural ones with neuroprotective activity and needed for further research.
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