Norepinephrine-induced Contraction Research Articles

Role of protein kinase D1 in vasoconstriction and haemodynamics in rats

AimsProtein kinase D (PKD), once considered an effector of protein kinase C (PKC), now plays many pathophysiological roles in various tissues. However, little is known about role of PKD in vascular function. We investigated the role of PKD in contraction of rat aorta and human aortic smooth muscle cells (HASMCs) and in haemodynamics in rats. Methods and resultsIsometric tension of rat aortic was measured to examine norepinephrine-induced contraction in the presence of PKD, PKC and Rho-kinase inhibitors. Phosphorylation of PKD1, myosin targeting subunit-1 (MYPT1), myosin light chain (MLC), CPI-17 and heat-shock protein 27 (HSP27), and actin polymerization were measured in the aorta. Phosphorylation of MYPT1 and MLC was also measured in HASMCs knocked down with specific siRNAs of PKD 1, 2 and 3. Intracellular calcium concentrations and cell shortening were measured in HASMCs.Norepinephrine-induced aortic contraction was accompanied by increased phosphorylation of PKD1, MYPT1 and MLC and actin polymerization, all of which were attenuated with PKD inhibitor CRT0066101. PKD1 phosphorylation was not inhibited by PKC inhibitor, chelerythrine or Rho kinase inhibitor, fasudil. In HASMCs, the phosphorylation of MYPT1 and MLC was attenuated by PKD1, but not PKD2, 3 knockdown. In HASMCs, CRT0066101 inhibited norepinephrine-induced cell shortening without affecting calcium concentration. Administration of CRT0066101 decreased systemic vascular resistance and blood pressure without affecting cardiac output in rats. ConclusionsPKD1 may play roles in aorta contraction and haemodynamics via phosphorylation of MYPT1 and actin polymerization in a calcium-independent manner.

AORTIC REACTIVITY IN VITAMIN D DEFICIENCY IN A RAT MODEL OF POLYCYSTIC OVARY SYNDROME

Objective: Polycystic ovary syndrome (PCOS) and vitamin D deficiency are associated with elevated cardiovascular risk, whereas vitamin D deficiency is a common comorbidity in PCOS that may contribute to the pathogenesis and complications of the disease. Our aim was to investigate the role of vitamin D status on the aortic function of hyperandrogenic female rats showing the symptoms of PCOS. Design and method: Female Wistar rats received an 8-week-long transdermal Androgel treatment to induce hyperandrogenism, another group remained untreated. Half of each group was fed with vitamin D reduced rat chow, while the other half received normal chow with further supplementation of vitamin D. Norepinephrine-induced contraction, acetylcholine, insulin, and estrogen-induced relaxation of thoracic aortae was examined by wire myography. Elastic fiber density was evaluated on resorcin-fuchsin stained tissue sections. Estrogen receptor alpha, endothelial nitric oxide synthase (eNOS), and cyclooxygenase 2 (COX-2) density and protein tyrosine nitration (NT) was measured by immunohistochemistry. Results: There was no difference in the norepinephrine-induced contraction of the aortas between experimental groups. Reduced acetylcholine-, insulin- and estrogen-evoked relaxation was observed in vitamin D deficient groups. A lower level of resorcin-fuchsin staining and elevated 3- nitrotyrosine immunostaining was observed in non-hyperandrogenic vitamin D deficient rats. eNOS staining intensity was reduced by vitamin D deficiency, while COX-2 density was increased by testosterone treatment. Estrogen receptor alpha density was increased by testosterone treatment but reduced by vitamin D deficiency. Conclusions: We demonstrated an early endothelial dysfunction in a rat model of vitamin D deficient polycystic ovary syndrome. Vitamin D supplementation could prevent vascular damage. On the other hand, vitamin D deficiency itself led to decreased endothelium-dependent relaxation and increased nitrative stress. Vitamin D deficiency also led to decreased estrogen receptor alpha and eNOS density independently from hyperandrogenism. Vitamin D deficiency found in approximately 80% of PCOS women may have a significant role in the development of vascular dysfunction and may contribute to their increased cardiovascular risk.

Effect of Vitamin D Status on Vascular Function of the Aorta in a Rat Model of PCOS.

Polycystic ovary syndrome (PCOS) is associated with elevated cardiovascular risk. Early vascular dysfunction may lead to the development of cardiovascular disease in PCOS. Vitamin D deficiency (VDD) is a common comorbidity of PCOS that contributes to the pathogenesis of the disease and its complications. Both PCOS and VDD are accompanied by increased oxidative stress that may be involved in the arising vascular dysfunction. We aimed to investigate the role of vitamin D status on aortic function. PCOS was induced by an 8-week-long transdermal testosterone treatment of female rats, and low and adequate vitamin D status was achieved by dietary means. Contraction and relaxation abilities of isolated aortic segments were measured by myograph. Resorcin-fuchsin staining and immunohistochemical labeling of 3-nitrotyrosine were performed. No difference was shown in the norepinephrine-induced contraction of the aortas of different groups, whereas we detected reduced acetylcholine- and insulin-evoked relaxation in VDD groups. A lower level of resorcin-fuchsin staining and elevated 3-nitrotyrosine immunostaining was observed in VDD. In our study, we demonstrated early endothelial dysfunction in VDD PCOS rat model. Vitamin D supplementation could prevent vascular disturbances, while VDD itself damaged endothelium-dependent vasorelaxation and induced nitrative stress.

Characteristic of the vasorlaxant action of the talatisamine alkaloid and its derivatives

The aim of our research is to study the effect relaxant action of diterpenoid alkaloids talatisamine, 14-O-benzoylthalatisamine and 14-O-acetylthalatisamine was studied using isolated rat aortic rings. Alkaloids significantly and dose-dependently inhibited contraction of the aortic rings caused by high KCl content. At the same time, under these conditions, alkaloids significantly reduced Ca2+-induced contraction of the aortic rings. The relaxing effects of alkaloids are significantly suppressed by verapamil, a potent potentiometer-dependent Ca2+ channel blocker. The alkaloids also significantly reduced norepinephrine-induced aortic ring contraction in normal as well as Ca2+ free Krebs solutions. The data obtained indicate that talatisamine, 14-benzoylthalatisamine and 14-O-acetylthalatisamine exhibit a pronounced relaxant effect in almost the same way in the case of contraction induced by a high content of KCl and norepinephrine. The mechanism of the relaxant action of alkaloids is probably complex and may include suppression of Ca2+influx through voltage-dependent and receptor-driven Ca2+ channels, as well as inhibition of Ca2+transport in the sarcoplasmic reticulum.

Characteristic of the vasorlaxant action of the talatisamine alkaloid and its derivatives

The aim of our research is to study the effect relaxant action of diterpenoid alkaloids talatisamine, 14-O-benzoylthalatisamine and 14-O-acetylthalatisamine was studied using isolated rat aortic rings. Alkaloids significantly and dose-dependently inhibited contraction of the aortic rings caused by high KCl content. At the same time, under these conditions, alkaloids significantly reduced Ca2+-induced contraction of the aortic rings. The relaxing effects of alkaloids are significantly suppressed by verapamil, a potent potentiometer-dependent Ca2+ channel blocker. The alkaloids also significantly reduced norepinephrine-induced aortic ring contraction in normal as well as Ca2+ free Krebs solutions. The data obtained indicate that talatisamine, 14-benzoylthalatisamine and 14-O-acetylthalatisamine exhibit a pronounced relaxant effect in almost the same way in the case of contraction induced by a high content of KCl and norepinephrine. The mechanism of the relaxant action of alkaloids is probably complex and may include suppression of Ca2+influx through voltage-dependent and receptor-driven Ca2+ channels, as well as inhibition of Ca2+transport in the sarcoplasmic reticulum.

Abstract 008: Aldosterone Contributes to the Blood Pressure Elevation, Endothelial Dysfunction, and Norepinephrine Sensitivity Caused by Endothelial Human Endothelin-1 Overexpression in Mice

Background: The mechanisms of blood pressure (BP) regulation by endothelin (ET)-1 produced by endothelial cells (ECs) are complex and remain unclear. Transgenic mice with tamoxifen-inducible EC-restricted human ET-1 overexpression (ieET-1) exhibited BP elevation 3 months after induction. ET-1 has been shown to stimulate the release of aldosterone from adrenal cortex (AC). Whether aldosterone plays a role in EC ET-1 overexpression-induced BP elevation and vascular injury is still unknown. Methods and results: Nine to 12-week-old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of EC-specific Tie2 promoter were treated with tamoxifen (1 mg/kg/day, SC) for 5 days and studied 3 months later. Plasma aldosterone levels measured by ELISA was increased in ieET-1 vs. ieCre mice (1.21±0.14 vs. 0.70±0.09 ng/mL, P <0.05). Reverse transcription-quantitative PCR (RT-qPCR) showed that aldosterone synthase ( Cyp11b2 ) was decreased in AC of ieET-1 vs. ieCre mice (fold change: 0.52±0.06 vs. 1.00±0.16, P <0.01). CYP11B2 protein levels measured by Western Blotting was unchanged. Treatment with mineralocorticoid receptor antagonist eplerenone (100 mg/kg/day) during the last 2 weeks decreased daytime systolic BP determined by telemetry in ieET-1 vs. ieCre mice (Systolic after 14 days [mm Hg]: 128±1.6 vs. 137±1.8, P <0.01). The EC50 concentration for norepinephrine-induced MA contraction was reduced in ieET-1 vs. ieCre mice (EC50 [mol/L]: 5x10 -7 ±6x10 -8 vs. 4x10 -6 ±7x10 -7 , P <0.05), which was reversed by elplerenone (EC50 [mol/L]: 8x10 -6 ±5x10 -6 , P <0.05). The MA relaxation response to acetylcholine was decreased in ieET-1 vs. ieCre mice (32.2±5.3% vs. 70.5±5.9%), effect that was reduced by eplerenone (43.1±5.5%). The MA endothelium-independent relaxation response to sodium nitroprusside (SNP) was similar in ieET-1 and ieCre mice. Eplerenone enhanced sensitivity to SNP in iET-1 mice (EC50 [mol/L]: 3x10 -8 ±1x10 -8 vs. 1x10 -7 ±2x10 -8 , P <0.05). Conclusions: Increased aldosterone production contributes to EC human ET-1 overexpression-induced daytime SBP elevation, enhanced contractile response to norepinephrine and endothelial dysfunction.

English

English

Remodeled structure and reduced contractile responsiveness of ocular ciliary artery in spontaneously hypertensive rats.

To investigate the alterations in both structure and contractile responsiveness of ocular ciliary artery (OCA) in spontaneously hypertensive rat (SHR). In this experiment, 20-week-old male SHR and Wistar Kyoto rat (WKY) were studied. The heart rate (HR), the blood pressure (BP; the systolic BP and the diastolic BP) of rats with an electronic sphygmomanometer were measured. Vascular morphometry and isometric tension measurement were used to investigate the alterations in structure and contractility of OCA. A general narrowing of OCAs was observed in SHR compared to the control WYK. In SHR, the media of OCAs were thicker, the luminal diameters were smaller, and the media-to-lumen ratios were higher when compared with WKY (P<0.05). The contractions of OCAs evoked by norepinephrine were smaller in SHR compared to control (P<0.05). Then, OCAs were pretreated with iberiotoxin, L-NAME, or indomethacin 30min before norepinephrine-induced contraction. Iberiotoxin (0.1 µmol/L) has not changed the norepinephrine-induced contractions in OCAs from both groups. However, L-NAME (100 µmol/L) increased the vasoconstrictions, the increased extents were similar in SHR and WKY (P>0.05). Indomethacin (10 µmol/L) decreased the contractions induced by norepinephrine in OCAs from WKY (P<0.05), but did not change those contractions in vessels from SHR (P>0.05). Our results demonstrate that the structure and function of OCAs are altered in hypertension. OCAs from SHR are remodeled with decreased lumen diameter and increased media-to-lumen ratio. Moreover, the contractile responsiveness of OCAs from SHR is diminished due to the disruption of vasoconstrictive effect of prostaglandins.

Comparison of Ca2+-dependent Cl-channels blockade and endothelium-derived constricting factor in norepinephrine-induced contraction of rat femoral artery

Comparison of Ca2+-dependent Cl-channels blockade and endothelium-derived constricting factor in norepinephrine-induced contraction of rat femoral artery

Contraction of Rat Cauda Epididymis Smooth Muscle to α1-Adrenoceptor Activation Is Mediated by α1A-Adrenoceptors.

The cauda epididymis (CE), the site of sperm storage until the ejaculation, is densely innervated by the sympathetic nervous system. Contraction of CE smooth muscle via α1-adrenoceptors (α1-ARs) plays a key role during the seminal emission phase of ejaculation and α1-AR antagonism has been suggested as a nonhormonal and reversible male contraceptive target. Since the α1-AR subtype mediating contraction of rat CE is not known, this study investigates the expression and role of α1-AR subtypes on the proximal and distal rat CE duct contraction to norepinephrine in vitro. Alpha1a, α1b, and α1d transcripts were detected by real-time quantitative polymerase chain reaction in proximal and distal CE segments and α1a and α1d were shown to predominate over α1b The inhibition of [3H]prazosin specific binding to intact CE segments from proximal and distal CE by RS 100329 and 5-methylurapidil (α1A-selective) and BMY 7378 (α1D-selective) showed that α1A- and α1D-ARs are expressed at similar densities. Norepinephrine-induced contractions of CE were competitively antagonized with high affinity by RS 100329 (pKB ≈ 9.50) and 5-methylurapidil (pKB ≈ 9.0) and with low affinity by BMY 7378 (pKB ≈ 7.0) and the α1B-selective L-765,314 (pA2 < 7.0), suggesting contractions are mediated by α1A-ARs. The clinically used α1A/D-ARs antagonist tamsulosin potently (pA2 ≈ 10.0) inhibited the norepinephrine-induced CE contractions. Altogether, our results show that α1A- and α1D-ARs are expressed in the CE duct and α1A-AR is the main subtype mediating contraction to norepinephrine. Our results highlight the importance of α1A-AR in the peripheral control of ejaculation and strengthen the α1A-AR as a target for a nonhormonal approach to male contraception.

Erratum to "Contribution of Ca2+-Dependent Cl- Channels to Norepinephrine-Induced Contraction of Femoral Artery Is Replaced by Increasing EDCF Contribution during Ageing".

[This corrects the article DOI: 10.1155/2014/289361.].

UPLC/Q-TOF-MS profiling of phenolics from Canarium pimela leaves and its vasorelaxant and antioxidant activities

Canarium pimela K.D. Koenig, Burseraceae, have a long history of use in the Chinese traditional medicine treatment of various ailments including hypertension, and our research team has reported the anti-hypertensive activity and delineated the mechanism involved in the action. The following research aims to evaluate the vasorelaxant and antioxidant activities of ethanol extract from C. pimela leaves and to analyze its chemical composition by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) that may correlate with their pharmacological activities. The results showed that pre-incubation of aortic rings with the extract (0.3, 1, 3, 10, 30 and 100mg/l) significantly inhibited the contractile response of the rings to norepinephrine-induced contraction (p<0.01or p<0.05). Crude ethanol extract and refined ethanol extract showed a highest inhibitory effect against 2,2dipheyl-2-picrylhydrazyl hydrate scavenging activity (IC50 of crude ethanol extract=15.42±0.14μg/ml and IC50 of refined ethanol extract=5.72±0.31μg/ml) and 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonic acid ammonium salt) (ABTS (IC50 of crude ethanol extract=3.24±0.18μg/ml and IC50 of refined ethanol extract=1.88±0.07μg/ml) scavenging activity, which was considerably higher than that reported for butylated hydroxytoluene and lower of that measured for ascorbic acid. Moreover, its chemical composition was analyzed by UPLC/Q-TOF-MS. Sixteen compounds including nine flavonoids, four tannins, two phenolic acids and one dianthrone were identified for the first time as constituents of this species. And of this, six major phenolic components were simultaneous quantitative analysis by HPLC-UV, chlorogenic acid is the major compounds in C. pimela leaves. These results indicate that the phenolic-rich extract of C. pimela leaves is a promising natural pharmaceutical for combating hypertension and oxidative stress.

Effects of losartan on vasomotor function and canonical transient receptor potential channels in the aortas of sinoaortic denervation rats

ABSTRACTIncreased short-term blood pressure variability (BPV) is strongly correlated with target organ damage. However, the molecular mechanisms underlying abnormal BPV-induced organ damage and effective therapeutic targets are poorly understood. The purpose of this study was to investigate the effects of losartan on vasomotor function and canonical transient receptor potential (TRPC) channels in the aortas of rats with arterial pressure lability induced by sinoaortic denervation (SAD). SAD was performed in male Sprague-Dawley rats at the age of 10 weeks. The experiment included sham-operated (Sham), SAD, and losartan-treated SAD (SAD+Los) groups. After 8 weeks of treatment, hemodynamic parameters were measured via catheterization, thoracic aortic vasomotor functions were evaluated using a physiological vascular ring tension recording system, and TRPC1 and 6 mRNA and protein expression levels in the endothelial cells (ECs) and smooth muscle cells (SMCs) of the thoracic aorta were determined via reverse transcription polymerase chain reaction (RT-PCR) and Western-blotting, respectively. Compared with Sham rats, SAD rats exhibited significantly increased BPV, enhanced norepinephrine-induced aortic contraction, and attenuated acetylcholine-induced aortic relaxation. Both the mRNA and the protein expression levels of TRPC1 and 6 were significantly downregulated in the ECs and upregulated in the SMCs of the thoracic aortas of SAD rats. Losartan treatment prevented these SAD-induced changes. In conclusion, losartan efficiently prevented vasomotor function impairment in SAD rats by reducing BPV and regulating TRPC1 and 6 expression levels.

Perivascular Adipose Tissue's Impact on Norepinephrine-Induced Contraction of Mesenteric Resistance Arteries.

Background: Perivascular adipose tissue (PVAT) can decrease vascular contraction to NE. We tested the hypothesis that metabolism and/or uptake of vasoactive amines by mesenteric PVAT (MPVAT) could affect NE-induced contraction of the mesenteric resistance arteries.Methods: Mesenteric resistance vessels (MRV) and MPVAT from male Sprague-Dawley rats were used. RT-PCR and Western blots were performed to detect amine metabolizing enzymes. The Amplex® Red Assay was used to quantify oxidase activity by detecting the oxidase reaction product H2O2 and the contribution of PVAT on the mesenteric arteries' contraction to NE was measured by myography.Results: Semicarbazide sensitive amine oxidase (SSAO) and monoamine oxidase A (MAO-A) were detected in MRV and MPVAT by Western blot. Addition of the amine oxidase substrates tyramine or benzylamine (1 mM) resulted in higher amine oxidase activity in the MRV, MPVAT, MPVAT's adipocyte fraction (AF), and the stromal vascular fraction (SVF). Inhibiting SSAO with semicarbazide (1 mM) decreased amine oxidase activity in the MPVAT and AF. Benzylamine-driven, but not tyramine-driven, oxidase activity in the MRV was reduced by semicarbazide. By contrast, no reduction in oxidase activity in all sample types was observed with use of the monoamine oxidase inhibitors clorgyline (1 μM) or pargyline (1 μM). Inhibition of MAO-A/B or SSAO individually did not alter contraction to NE. However, inhibition of both MAO and SSAO increased the potency of NE at mesenteric arteries with PVAT. Addition of MAO and SSAO inhibitors along with the H2O2 scavenger catalase reduced PVAT's anti-contractile effect to NE. Inhibition of the norepinephrine transporter (NET) with nisoxetine also reduced PVAT's anti-contractile effect to NE.Conclusions: PVAT's uptake and metabolism of NE may contribute to the anti-contractile effect of PVAT. MPVAT and adipocytes within MPVAT are a source of SSAO.

Proanthocyanidins from Vitis vinifera inhibit oxidative stress-induced vascular impairment in pulmonary arteries from diabetic rats

Vitis vinifera L. (grape seed extract) is a natural source of proanthocyanidins with antioxidant and free radical-scavenging activities. Grape seed extract supplementation may prevent vascular endothelium impairment associated with diabetes mellitus in rat pulmonary artery. We evaluated endothelial function of rat pulmonary artery ex-vivo at the intermediate stage (4 weeks) of streptozotocin (STZ)-induced diabetes mellitus. We also evaluated the protective effect of grape seed extract administered daily, beginning the day after diabetes induction, or 15 days after diabetes induction, until the day of sacrifice. In addition, we compared the effect of grape seed extract supplementation with that of vitamin C. Rats were made diabetic with streptozotocin (STZ, 65mg/kg i.v.). Thirty days later rats were sacrificed and pulmonary vessels reactivity and endothelial function compared to that of age-matched healthy animals. Concentration-response curves to ACh, NE, sodium nitroprusside (NO donor), but not to histamine and iloprost (prostacyclin analog), were significantly altered 4 weeks after STZ-injection. Antioxidant supplementation (3mg/kg/day) with either vitamin C or grape seed extract, starting the day after diabetes induction, significantly improved vasodilation to ACh and SNP. Norepinephrine-induced contractions were preserved by grape seed extract, but not vitamin C supplementation. Conversely, vitamin C but not grape seed extract showed beneficial effects contrasting the loss of body weight in diabetic animals. Abnormal vascular function was not reversed when antioxidant supplementations were postponed 15 days after the induction of diabetes. This study provides scientific support for the therapeutic potential of an antioxidant therapy in endothelial impairment associated with diabetes. A daily supplementation of grape seed proanthocyanidins and/or vitamin C given at the earlier stage of disease may have a complementary role in the pharmacological therapy of diabetes and pulmonary vascular dysfunction.

OS 02-06 PHYSIOLOGICAL REGULATION OF VASOMOTION BY INTRACELLULAR ATP-MEDIATED SYSTEM IN HUMAN ARTERY.

Spontaneous oscillation of tone of blood vessel called vasomotion cause vessel to flow blood which is an oscillation of flow into an organ. Microcirculation is sensitive to hypoxic condition and metabolism but mechanism of vasomotion is still poorly understood. Purpose: We studied involvement of metabolism-mediated regulation by intracellular ATP level of vasomotion in human gastric artery. Conventional contractile measuring system and Western blot were used. Circular muscle of human gastric artery produced sustained tonic contraction of 1.0 ± 0.19 g by 50 mM high K (n = 36). Pinacidil (10 μM), which is known to activatorof ATP-sensitive K (KATP) channel inhibited vasomotion completely in a reversible manner. Inhibition of vasomotion by activators of KATP channel recovered by glibenclamide. Diazoxide (300 μM), cromakalim (10 μM) nicorandil (10 μM) which is known to activate KATP channel also completely blocked vasomotion in a glibenclamide sensitive manner. Inhibitory effect of these openers of KATP channel on serotonin and norepinephrine-induced contraction were also recoded in a glibenclmide-sensitive manner. In human artery, glucose-free condition which is elated metabolic changes inhibited vasomotion and it was recovered by glibenclamide. Finally, molecular subtypes of KATP channel was defined by Western blot in human artery. Vasomotion of human gastroepiploic artery was inhibited by activation of specific subtypes of KATP channel and alteration of metabolism.

The adipokine chemerin amplifies electrical field-stimulated contraction in the isolated rat superior mesenteric artery.

The adipokine chemerin causes arterial contraction and is implicated in blood pressure regulation, especially in obese subjects with elevated levels of circulating chemerin. Because chemerin is expressed in the perivascular adipose tissue (PVAT) that surrounds the sympathetic innervation of the blood vessel, we tested the hypothesis that chemerin (endogenous and exogenous) amplifies the sympathetic nervous system in mediating electrical field-stimulated (EFS) contraction. The superior mesenteric artery, with or without PVAT and with endothelium and sympathetic nerve intact, was mounted into isolated tissue baths and used for isometric contraction and stimulation. Immunohistochemistry validated a robust expression of chemerin in the PVAT surrounding the superior mesenteric artery. EFS (0.3-20 Hz) caused a frequency-dependent contraction in isolated arteries that was reduced by the chemerin receptor ChemR23 antagonist CCX832 alone (100 nM; with, but not without, PVAT), but not by the inactive congener CCX826 (100 nM). Exogenous chemerin-9 (1 μM)-amplified EFS-induced contraction in arteries (with and without PVAT) was blocked by CCX832 and the α-adrenergic receptor antagonist prazosin. CCX832 did not directly inhibit, nor did chemerin directly amplify, norepinephrine-induced contraction. Whole mount immunohistochemical experiments support colocalization of ChemR23 with the sympathetic nerve marker tyrosine hydroxylase in superior mesenteric PVAT and, to a lesser extent, in arteries and veins. These studies support the idea that exogenous chemerin modifies sympathetic nerve-mediated contraction through ChemR23 and that ChemR23 may be endogenously activated. This is significant because of the well-appreciated role of the sympathetic nervous system in blood pressure control.

From Newborn to Senescence Morphological and Functional Remodeling Leads to Increased Contractile Capacity of Arteries.

Aging induces substantial morphological and functional changes in vessels. We hypothesized that due to morphological remodeling the total contractile forces of arteries increase, especially in older age as a function of age. Mean arterial blood pressure of rats and morphological and functional characteristics of isolated carotid arteries rats, from newborn to senescent, were assessed. The arterial blood pressure of rats increased significantly from 0.25 to the age of 6 months, and then it reached a level, which was maintained until age of 30 months. Wall lumen and wall thickness increased with age, mostly due to media (smooth muscle) thickening, whereas wall tension gradually reduced with age. Contractions of arteries to nonreceptor-mediated vasomotor agent (KCl, 60mM) increased in three consecutive age groups, whereas contractility first increased (until 2 months), then it did not change further with aging. Norepinephrine-induced contractions initially increased in young age and then did not change further in older age. These findings suggest that during normal aging due to remodeling of arterial wall (smooth muscle) the contractile capacity of arteries increases, which seems to be independent from systemic blood pressure. Thus, arterial remodeling can favor the development of increased circulatory resistance in older age.

In vitro vasorelaxation mechanisms of Isoapiole extracted from Lemonfragrant Angelica Root on rat thoracic aorta

Ethnopharmcological relevanceLemonfragrant Angelica (Ostericum citriodorum (Hance) C. Q. Yuan & Shan) is a traditional Chinese herb for treatment of angina pectoris, stomach pain and abdominal pain. However, its active components and mechanisms of action were not well understood. Aims of the studyIn this study, we investigated whether the isoapiole extracted from Lemonfragrant Angelica Root (LAR) could directly stimulate the production of nitric oxide (NO) in vascular endothelial cells (VECs) and lead to the vascular relaxation Materials and methodsVascular activity experiments were performed in aortic rings isolated from Wistar rats using standard muscle bath procedures. Isoapiole was added with different concentrations (0.75, 2.5, 5μg/mL), and vessel relaxation of rat aortic rings pre-contracted with norepinephrine (NE) or potassium chloride was recorded. NO release from aortic rings exposed to isoapiole (5μg/mL) was measured by Griess method. The endothelial nitric oxide synthase (eNOS) expression in primary human umbilical vein endothelial cells (HUVECs) incubated with isoapiole was determined using Western blot and microplate reader assay. Classical receptor antagonists, channel and enzymatic inhibitors were used to check the mechanisms involved. ResultsIsoapiole (0.75, 2.5, 5μg/mL) inhibited norepinephrine-induced contraction in endothelium-intact rat aortic rings. However, a very weak relaxation of aortic rings was obtained in endothelium-denuded preparations. Isoapiole (0.75, 2.5, 5μg/mL) did not have vascular relaxative effect on neither endothelium-intact nor endothelium-denuded aortas pre-contracted with KCl (60mmol/L). The vasorelaxation effect of isoapiole on rat aortic rings was attenuated by the eNOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). This result suggested that suggested that the isoapiole action was at least partially mediated by promoting eNOS expression. It was further found that isoapiole (5μg/mL) increased NO production in isolated rat thoracic aorta rings. Isoapiole increased eNOS expression leading to NO production in HUVECs. ConclusionIsoapiole stimulates NO production in the endothelium, leading to vascular dilatation.

Plasmonic gold nanoparticles possess the ability to open potassium channels in rat thoracic aorta smooth muscles in a remote control manner

Colloidal gold nanoparticles (AuNPs) of ~5nm core size and Zeta-potential of −35mV, having absorption maximum and plasmon resonance in the range of 510–570nm, were studied as a potential K+-channel opener in vascular smooth muscle (SM) cells. Experimental design of the study comprised SM contractile recordings.When externally applied to the organ bath, AuNPs (10−6−3×10−4M) led to decrease in amplitude of norepinephrine-induced contractions in a concentration-dependent and endothelium-independent manner in SM thoracic aorta, with mean value of pD2 (−log EC50) 4.2±0.03, Emax=55±4%. Being added to the bath solution in concentration of 10−4M, AuNPs significantly increased whole cell peak outward current at +70mV from 32±2pA/pF to 59±5pA/pF (n=14, P<0.05). External irradiation using a 5mW/532nm green laser, to facilitate plasmon resonance, led to an increment in the AuNPs-induced macroscopic outward potassium current (IK) from 59±5pA/pF to 74±1pA/pF (n=10, P<0.05). Paxilline (500nM), when added to the external bathing solution, significantly decreased AuNPs-induced increment of IK in SM cells. Single channel recordings provided a direct confirmation of BKCa activation by AuNPs at the single-channel level. Application of AuNPs to the bath potentiated BKCa activity with a delay of 1–2min, as was seen initially by more frequent channel openings followed by the progressive appearance of additional open levels corresponding to multiple openings of channels with identical single-channel amplitudes. Eventually, after 10–15min in the presence of AuNPs and especially when combined with the green laser illumination, there was a massive increase in channel activity with >10 channels evident. When irradiated by laser, AuNPs significantly increased the amplitude of maximal AuNPs-induced relaxation from 55±5% to 85±5% (n=10, P<0.05) while the sensitivity of SM to AuNPs was without changes.In summary, plasmonic AuNPs possess the ability to activate BKCa channel opening in vascular SM. Laser irradiation facilitates this effect due to local plasmon resonance that, in turn, further increases BKCa channel activity causing SM relaxation.