Prostacyclin Release Research Articles

Magnesium in hypertension: mechanisms and clinical implications.

Hypertension is associated with increased risk of cardiovascular disease and death. Evidence suggests that Mg2+ depletion contributes to hypertension. It is estimated that 25% or more of the United States population experiences chronic, latent Mg2+ depletion. This review explores mechanisms by which Mg2+ influences blood pressure, modifying risk of hypertension and complicating its treatment. Mechanisms addressed include effects upon i) sympathetic tone, via the modulation of N-methyl-D-aspartate (NMDA) receptor and N-type Ca2+ channel activity, influencing catecholamine release from sympathetic nerve endings; ii) vascular tone, via alteration of L-type Ca2+ and endothelial nitric oxide synthase (eNOS) activity and prostacyclin release; iii) renal K+ handling, influencing systemic K+ balance and potentially indirectly influencing blood pressure; iv) aldosterone secretion from the adrenal cortex; and v) modulation of pro-hypertensive inflammatory processes in dendritic cells and macrophages, including activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome and stimulation of isolevuglandin (IsoLG) production. Discovery of these mechanisms has furthered our understanding of the pathogenesis of hypertension, with implications for treatment and has highlighted the role of Mg2+ balance in hypertension and cardiovascular disease.

Widening the Prostacyclin Paradigm: Tissue Fibroblasts Are a Critical Site of Production and Antithrombotic Protection.

Prostacyclin is a fundamental signaling pathway traditionally associated with the cardiovascular system and protection against thrombosis but which also has regulatory functions in fibrosis, proliferation, and immunity. Prevailing dogma states that prostacyclin is principally derived from vascular endothelium, although it is known that other cells can also synthesize it. However, the role of nonendothelial sources in prostacyclin production has not been systematically evaluated resulting in an underappreciation of their importance relative to better characterized endothelial sources. To address this, we have used novel endothelial cell-specific and fibroblast-specific COX (cyclo-oxygenase) and prostacyclin synthase knockout mice and cells freshly isolated from mouse and human lung tissue. We have assessed prostacyclin release by immunoassay and thrombosis in vivo using an FeCl3-induced carotid artery injury model. We found that in arteries, endothelial cells are the main source of prostacyclin but that in the lung, and other tissues, prostacyclin production occurs largely independently of endothelial and vascular smooth muscle cells. Instead, in mouse and human lung, prostacyclin production was strongly associated with fibroblasts. By comparison, microvascular endothelial cells from the lung showed weak prostacyclin synthetic capacity compared with those isolated from large arteries. Prostacyclin derived from fibroblasts and other nonendothelial sources was seen to contribute to antithrombotic protection. These observations define a new paradigm in prostacyclin biology in which fibroblast/nonendothelial-derived prostacyclin works in parallel with endothelium-derived prostanoids to control thrombotic risk and potentially a broad range of other biology. Although generation of prostacyclin by fibroblasts has been shown previously, the scale and systemic activity was unappreciated. As such, this represents a basic change in our understanding and may provide new insight into how diseases of the lung result in cardiovascular risk.

Anti-Cancer Prodrug Cyclophosphamide Exerts Thrombogenic Effects on Human Venous Endothelial Cells Independent of CYP450 Activation-Relevance to Thrombosis.

Cancer patients are at a very high risk of serious thrombotic events, often fatal. The causes discussed include the detachment of thrombogenic particles from tumor cells or the adverse effects of chemotherapeutic agents. Cytostatic agents can either act directly on their targets or, in the case of a prodrug approach, require metabolization for their action. Cyclophosphamide (CPA) is a widely used cytostatic drug that requires prodrug activation by cytochrome P450 enzymes (CYP) in the liver. We hypothesize that CPA could induce thrombosis in one of the following ways: (1) damage to endothelial cells (EC) after intra-endothelial metabolization; or (2) direct damage to EC without prior metabolization. In order to investigate this hypothesis, endothelial cells (HUVEC) were treated with CPA in clinically relevant concentrations for up to 8 days. HUVECs were chosen as a model representing the first place of action after intravenous CPA administration. No expression of CYP2B6, CYP3A4, CYP2C9 and CYP2C19 was found in HUVEC, but a weak expression of CYP2C18 was observed. CPA treatment of HUVEC induced DNA damage and a reduced formation of an EC monolayer and caused an increased release of prostacyclin (PGI2) and thromboxane (TXA) associated with a shift of the PGI2/TXA balance to a prothrombotic state. In an in vivo scenario, such processes would promote the risk of thrombus formation.

The role of endothelial dysfunction, microcirculatory disorders, and hypoxia as mechanisms for the formation of lung lesions

In a review article, the authors consider the significance of endothelial dysfunction, microcirculation disorders, and hypoxia in the development of lung diseases and in the comorbid course of a number of other diseases of the internal organs. The role of endotheliocytes in the systemic response to inflammatory processes in the case of damage to the bronchopulmonary system is considered. Endothelial cells counteract pathogens in the blood and send signals warning of infection, invasion, or injury. The importance of the anticoagulant and antithrombotic properties of the endothelium (including the pulmonary one), which contribute to the fight against thrombosis, is emphasized. It is indicated that endothelial cells have an endogenous mechanism to combat platelet activation. This function depends on the surface expression of ecto-ATPase, CD39, and the release of nitric oxide and prostacyclin. Attention is paid to the importance of activation of the renin-angiotensin-aldosterone system both through angiotensin-II and through aldosterone. The authors stressed the importance of endothelial dysfunction as an imbalance between the factors of relaxation and constriction, coagulation, and fibrinolysis, which provide hemostasis of the main vital regulatory systems, and the stage of disease compensation (via the participation of nitric oxide). Microcirculation disorders and hypoxia are considered phenomena that are compatible in pathogenesis not only with pulmonary diseases but also as common comorbid syndromes with other diseases of the internal organs. This is explained by the fact that the common links are chronic oxidative stress, the reaction of the immune system to damage, the formation of a low-grade chronic systemic inflammation syndrome, a violation of the microcirculation process, and an increase in hypoxic and ischemic processes. The importance of knowledge about the mechanisms of development of endothelial dysfunction, microcirculation disorders, and hypoxia for therapeutic and rehabilitation tactics is emphasized.

Renal Function Underpins the Cyclooxygenase-2: Asymmetric Dimethylarginine Axis in Mouse and Man

Through the production of prostacyclin, cyclooxygenase (COX)-2 protects the cardiorenal system. Asymmetric dimethylarginine (ADMA), is a biomarker of cardiovascular and renal disease. Here we determined the relationship between COX-2/prostacyclin, ADMA, and renal function in mouse and human models. We used plasma from COX-2 or prostacyclin synthase knockout mice and from a unique individual lacking COX-derived prostaglandins (PGs) because of a loss of function mutation in cytosolic phospholipase A2 (cPLA2), before and after receiving a cPLA2-replete transplanted donor kidney. ADMA, arginine, and citrulline were measured using ultra-high performance liquid-chromatographytandem mass spectrometry. ADMA and arginine were also measured by enzyme-linked immunosorbent assay (ELISA). Renal function was assessed by measuring cystatin C by ELISA. ADMA and prostacyclin release from organotypic kidney slices were also measured by ELISA. Loss of COX-2 or prostacyclin synthase in mice increased plasma levels of ADMA, citrulline, arginine, and cystatin C. ADMA, citrulline, and arginine positively correlated with cystatin C. Plasma ADMA, citrulline, and cystatin C, but not arginine, were elevated in samples from the patient lacking COX/prostacyclin capacity compared to levels in healthy volunteers. Renal function, ADMA, and citrulline were returned toward normal range when the patient received a genetically normal kidney, capable of COX/prostacyclin activity; and cystatin C positively correlated with ADMA and citrulline. Levels of ADMA and prostacyclin in conditioned media of kidney slices were not altered in tissue from COX-2 knockout mice compared to wildtype controls. In human and mouse models, where renal function is compromised because of loss of COX-2/PGI2 signaling, ADMA levels are increased.

Cellular response to photo-mediated ultrasound therapy

Photo-mediated ultrasound therapy (PUT) is a novel technique that combines relatively low-pressure focused ultrasound and low-fluence laser to enhance cavitation inside blood vessels. Due to the increased shear and circumferential stresses, the enhanced cavitation activity can achieve anti-vascular effect. The role of endothelial cells in the antivascular effect of PUT was explored by quantifying the release of vasodilators-nitric oxide and prostacyclin from endothelial cells after PUT, laser-only, and ultrasound-only therapies in an in vitro vessel mode. PUT was able to suppress both the vasodilators by more than 5% with concurrently applied 0.5MPa ultrasound pressure at 500 kHz and 15 mJ/cm2 laser fluence at 532 nm. Both the laser-only and ultrasound-only therapies at the similar levels resulted only in elevation of these vasodilators with respect to control. The suppression of vasodilators by PUT was justified with cavitation signals observed using passive cavitation detection and apoptosis observed with Annexin V-fluorescein isothiocyante (FITC), at respective levels. The endothelial cellular response to PUT further motivated us to evaluate the effect of PUT on melanoma cells and evaluate cytotoxic effect through MTT assay. PUT was able to destroy cancer cells through the cavitation effect when compared to laser-only and ultrasound-only therapies at the similar energy levels.

Abstract 14698: Identifying Sources of Prostacyclin Outside the Vascular Wall and Their Contribution to Cardiovascular Protection

Introduction: Prostacyclin is a key anti-thrombotic hormone synthesised through cyclooxygenase (COX) enzymes. Historically, its production has been almost universally associated with the endothelium however the role of non-vascular sources has not been systematically evaluated due to a lack of suitable tools. This has resulted in an underappreciation of its cardiovascular biology and role in other contexts. Hypothesis: We hypothesised that cells outside the vascular wall contribute to generation of prostacyclin which can enter the circulation to provide anti-thrombotic protection. Methods: Global, endothelial and fibroblast COX1 or COX2 knockout mice were studied alongside freshly isolated healthy human lung tissue and primary cell cultures. Prostacyclin levels in plasma and released from cells/tissue ex vivo were measured by ELISA. Individual cell populations were isolated by FACS. Thrombosis in vivo was measured using a FeCl 3 -carotid artery injury model. Results: Vascular endothelial COX1 deletion strongly reduced prostacyclin release from mouse aorta and heart, but not from isolated lung, colon, kidney or spleen (Fig A). This non-vascular prostacyclin required COX1 as it was abolished by global COX1 and not COX2 deletion. Freshly isolated lung fibroblasts exhibited greater prostacyclin synthesis than endothelial or other cell types (Fig B) and this was confirmed in primary human lung cell cultures. Deletion of COX1 from fibroblasts in mice reduced lung prostacyclin release (Fig C) and plasma prostacyclin levels (Fig D) and this was associated with accelerated thrombotic occlusion after carotid artery injury (Fig E). Conclusions: These findings define a new paradigm in prostacyclin biology in which fibroblast/non-vascular-derived prostacyclin works in parallel with endothelium-derived prostanoids to control thrombosis. This may have particular relevance to understanding how local diseases of the lung result in cardiovascular risk.

Lipid Droplets Formation Represents an Integral Component of Endothelial Inflammation Induced by LPS.

Endothelial inflammation is the hallmark of vascular pathology often proceeding with cardiovascular diseases. Here, we adopted a multiparameter approach combining various imaging techniques at the nano- and microscale (Raman, AFM and fluorescence) to investigate endothelial inflammation in response to lipopolysaccharides (LPS) in vitro in human microvascular endothelial cells (HMEC-1) with a focus on lipid droplets (LDs) formation. Our results show that LPS-induced LDs in HMEC-1 have a composition depending on LPS-incubation time and their formation requires the presence of serum. Robust endothelial inflammation induced by LPS was linked to LDs composed of highly unsaturated lipids, as well as prostacyclin release. LPS-induced LDs were spatially associated with nanostructural changes in the cell membrane architecture. In summary, LDs formation represents an integral component of endothelial inflammation induced by LPS.

Mesenteric traction syndrome in pigs: A single-blinded, randomized controlled trial.

BackgroundMesenteric traction syndrome is commonly observed in patients undergoing upper abdominal surgery and is associated with severe postoperative complications. A triad of hypotension, tachycardia, and facial flushing seems provoked by prostacyclin (PGI2) release from the gut in response to mesenteric traction. The administration of nonsteroidal anti‐inflammatory drugs (NSAID) inhibits PGI2 release, stabilizing the hemodynamic response. Here, we examined the effect of mesenteric traction on splanchnic blood flow in pigs randomized to NSAID or placebo treatment.Materials and MethodsTwenty pigs were allocated to either ketorolac or placebo treatment. Five minutes of manual mesenteric traction was applied. Plasma 6‐keto‐PGF1α, a stable metabolite of PGI2, hemodynamic variables, and regional blood flow (laser speckle contrast imaging) to the liver, stomach, small intestine, upper lip, and snout (laser Doppler flowmetry) were recorded prior to traction and 5 and 30 minutes thereafter.ResultsBoth groups of pigs presented a decrease in systemic vascular resistance (P = .01), mean arterial blood pressure (P = .001), and blood flow in the gastric antrum (P = .002). Plasma 6‐keto‐PGF1α did not increase in either group (P = .195), and cardiac output, heart rate, central venous pressure, and blood flow to the liver, small intestine, upper lip, and snout remained unchanged.ConclusionMesenteric traction resulted in cardiovascular depression, including reduced blood flow in the gastric antrum. Plasma 6‐keto‐PGF1α did not increase, and ketorolac administration did not alter the response to mesenteric traction. Furthers studies are needed to identify which substance is responsible for eliciting the cardiovascular response to mesenteric traction in pigs.

The Effect of Platelet-Rich Plasma on Endothelial Progenitor Cell Functionality.

Platelets mediate circulating endothelial progenitor cell (EPC) recruitment and maturation, participating in vascular repair, however the underlying mechanism(s) remain unclear. We investigated the effect of platelet-rich plasma (PRP) on the functionality of CD34+-derived late-outgrowth endothelial cells (OECs) in culture. Confluent OECs were coincubated with PRP under platelet aggregation (with adenosine diphosphate; ADP) and nonaggregation conditions, in the presence/absence of the reversible P2Y12 platelet receptor antagonist ticagrelor. Outgrowth endothelial cell activation was evaluated by determining prostacyclin (PGI2) and monocyte chemoattractant protein-1 (MCP-1) release and intercellular adhesion molecule-1 (ICAM-1) membrane expression. Similar experiments were performed using human umbilical vein endothelial cells (HUVECs). Platelet-rich plasma increased ICAM-1 expression and PGI2 and MCP-1 secretion compared with autologous platelet-poor plasma, whereas ADP-aggregated platelets in PRP did not exhibit any effect. Platelet-rich plasma pretreated with ticagrelor prior to activation with ADP increased all markers to a similar extent as PRP. Similar results were obtained using HUVECs. In conclusion, PRP induces OEC activation, a phenomenon not observed when platelets are aggregated with ADP. Platelet inhibition with ticagrelor restores the PRP capability to activate OECs. Since EPC activation is important for endothelial regeneration and angiogenesis, we suggest that agents inhibiting platelet aggregation, such as ticagrelor, may promote platelet-EPC interaction and EPC function.

Response of Endothelial Cells to Gelatin-Based Hydrogels

The establishment of confluent endothelial cell (EC) monolayers on implanted materials has been identified as a concept to avoid thrombus formation but is a continuous challenge in cardiovascular device engineering. Here, material properties of gelatin-based hydrogels obtained by reacting gelatin with varying amounts of lysine diisocyanate ethyl ester were correlated with the functional state of hydrogel contacting venous EC (HUVEC) and HUVEC's ability to form a monolayer on these hydrogels. The density of adherent HUVEC on the softest hydrogel at 37 °C (G' = 1.02 kPa, E = 1.1 ± 0.3 kPa) was significantly lower (125 mm-1) than on the stiffer hydrogels (920 mm-1; G' = 2.515 and 5.02 kPa, E = 4.8 ± 0.8 and 10.3 ± 1.2 kPa). This was accompanied by increased matrix metalloprotease activity (9 pmol·min-2 compared to 0.6 pmol·min-2) and stress fiber formation, while cell-to-cell contacts were comparable. Likewise, release of eicosanoids (e.g., prostacyclin release of 1.7 vs 0.2 pg·mL-1·cell-1) and the pro-inflammatory cytokine MCP-1 (8 vs <1.5 pg·mL-1·cell-1) was higher on the softer than on the stiffer hydrogels. The expressions of pro-inflammatory markers COX-2, COX-1, and RAGE were slightly increased on all hydrogels on day 2 (up to 200% of the control), indicating a weak inflammation; however, the levels dropped to below the control from day 6. The study revealed that hydrogels with higher moduli approached the status of a functionally confluent HUVEC monolayer. The results indicate the promising potential especially of the discussed gelatin-based hydrogels with higher G' as biomaterials for implants foreseen for the venous system.

Protective effects of luteolin on the venous endothelium.

Luteolin is a flavonoid with antioxidant properties already demonstrated in studies related to inflammation, tumor, and cardiovascular processes; however, there are no available information regarding its antioxidant effects at the venous endothelial site. We investigated the effects of luteolin (10, 20, and 50μmol/L) in cultures of rat venous endothelial cells. Nitric oxide (NO) and reactive oxygen species (ROS) were analyzed by fluorimetry; 3-nitrotyrosine (3-NT) residues were evaluated by immunofluorescence, and prostacyclin (PGI2) release was investigated by colorimetry. Intracellular NO levels were significantly enhanced after 10min of luteolin incubation, with a parallel decrease in ROS generation. These results were accompanied by a significant reduction in the expression of 3-NT residues and enhanced PGI2 rates. Therefore, luteolin is effective in reducing ROS thereby improving NO availability in venous endothelial cells. Besides, luteolin-induced decrease in 3-NT residues may correlate with the enhancement in endothelial PGI2 bioavailability. These findings suggest the future application of this flavonoid as a protective agent by improving endothelial function in several circulatory disorders related to venous insufficiency.

Increased prostacyclin formation after high-intensity interval training in late postmenopausal women.

Aging impairs vascular function in women, with the largest detrimental effects occurring during the menopausal transition. Deficiency in the nitric oxide system has been suggested to be responsible for impairment in vascular function with aging, but recent observations suggest that the prostacyclin system, acting in redundancy with the nitric oxide system, may be of importance too. Improvement in vascular function is a hallmark of exercise training and we hypothesize that leg vascular function is improved by exercise training in late postmenopausal women, and that the underlying mechanism is increased endothelial formation of prostacyclin and responsiveness to prostacyclin by the vascular smooth muscle cells. Femoral-arterial infusion of acetylcholine and epoprostenol was used to assess vascular function and prostacyclin release in ten late postmenopausal women (62 ± 7years) before and after 10weeks of high-intensity interval training (floorball conducted as small-sided games). The training intervention increased fitness level (V̇O2max) by 7 ± 7% and reduced systolic and diastolic blood pressure by 10 ± 10 and 5 ± 6mmHg, respectively. Leg vascular responsiveness to during acetylcholine and epoprostenol infusion was unchanged with training, whereas the release of prostacyclin during acetylcholine infusion increased by 125%. In late postmenopausal women, vascular function assessed by femoral-arterial infusion of acetylcholine was not improved after 10weeks of floorball training, but acetylcholine-induced prostacyclin formation and blood pressure were substantially improved. It is possible that a longer training period could lead to improvements in vascular function and that the observed increase in prostacyclin formation is one of the initial underlying changes.

Mechanisms underlying the vascular relaxation activities of Zingiber officinale var. rubrum in thoracic aorta of spontaneously hypertensive rats

ObjectiveTo evaluate vasorelaxant and vasoconstriction effects of Zingiber officinale var. rubrum (ZOVR) on live rats and isolated aortic rings of spontaneously hypertensive rats (SHRs). MethodsExtracts of ZOVR were subjected to in-vivo antihypertensive screening using noninvasive blood pressures in SHRs. The most potent extract, ZOVR petroleum ether extract (ZOP) was then fractionated using n-hexane, chloroform and water. Isolated thoracic aortic rings were harvested and subjected to vascular relaxation studies of n-hexane fraction of ZOP (HFZOP) with incubation of different antagonists such as Nω-nitro-l-arginine methyl ester (L-NAME, 10 µmol/L), indomethacin (10 µmol/L), methylene blue (10 µmol/L), atropine (1 µmol/L), glibenclamide (10 µmol/L), prazosin (0.01 µmol/L), and propranolol (1 µmol/L). ResultsDuring the screening of various ZOVR extracts, ZOP produced the most reduction in blood pressures of SHRs and so did HFZOP. HFZOP significantly decreased phenylephrine-induced contraction and enhanced acetylcholine-induced relaxation. L-NAME, indomethacin, methylene blue, atropine, and glibenclamide significantly potentiated the vasorelaxant effects of HFZOP. Propranolol and prazosin did not alter the vasorelaxant effects of HFZOP. HFZOP significantly suppressed the Ca2+-dependent contraction and influenced the ratio of the responses to phenylephrine in Ca2+-free medium. ConclusionThis study demonstrates that ZOP may exert an antihypertensive effect in the SHR model. Its possible vascular relaxation mechanisms involve nitric oxide and prostacyclin release, activation of cGMP-KATP channels, stimulation of muscarinic receptors, and transmembrane calcium channel or Ca2+ release from intracellular stores. Possible active compounds that contribute to the vasorelaxant effects are 6-gingerol, 8-gingerol and 6-shogaol.

Development of a severe mesenteric traction syndrome during major abdominal surgery is associated with increased postoperative morbidity: Secondary data analysis on prospective cohorts.

MTS is elicited during open abdominal surgery and is characterized by facial flushing, hypotension, and tachycardia in response to the release of prostacyclin (PGI2) to plasma. MTS seems to affect postoperative morbidity, but data from larger cohorts are lacking. We aimed to determine the impact of severe mesenteric traction syndrome (MTS) on postoperative morbidity in patients undergoing open upper gastrointestinal surgery. The study was a secondary analysis of data from three cohorts (n = 137). The patients were graded for severity of MTS intraoperatively, and hemodynamic variables and blood samples for plasma 6-keto-PGF1α, a stable metabolite of PGI2, were obtained at defined time points. Postoperative morbidity was evaluated by the comprehensive complication index (CCI) and the Dindo-Clavien classification (DC). Patients undergoing either esophagectomy (n = 70), gastrectomy (n = 22), liver- (n = 23), or pancreatic resection (n = 22) were included. Severe MTS was significantly associated with increased postoperative morbidity, i.e., CCI ≥ 26.2 (OR 3.06 [95% CI 1.1-6.6]; p = 0.03) and risk of severe complications, i.e., DC ≥3b (OR 3.1 [95% CI 1.2-8.2]; p = 0.023). Furthermore, patients with severe MTS had increased length of stay (OR 10.1 [95% CI 1.9-54.3]; p = 0.007) and were more likely to be admitted to the intensive care unit (OR = 7.3 [95% CI 1.3-41.9]; p = 0.027), but there was no difference in 1-year mortality. Occurrence of severe MTS during upper gastrointestinal surgery is associated with increased postoperative morbidity as indicated by an increased rate of severe complications, length of stay, and admission to the ICU. It remains to be determined whether inhibition of MTS enhances postoperative recovery.

Gelatin-based perfusable, endothelial carotid artery model for the study of atherosclerosis

BackgroundCarotid artery geometry is important for recapitulating a pathophysiological microenvironment to study wall shear stress (WSS)-induced endothelial dysfunction in atherosclerosis. Endothelial cells (ECs) cultured with hydrogel have been shown to exhibit in vivo-like behaviours. However, to date, studies using hydrogel culture have not fully recapitulated the 3D geometry and blood flow patterns of real-life healthy or diseased carotid arteries. In this study, we developed a gelatin-patterned, endothelialized carotid artery model to study the endothelium response to WSS.ResultsTwo representative regions were selected based on the computational fluid dynamics on the TF-shaped carotid artery: Region ECA (external carotid artery) and Region CS (carotid sinus). Progressive elongation and alignment of the ECs in the flow direction were observed in Region ECA after 8, 16 and 24 h. However, the F-actin cytoskeleton remained disorganized in Region CS after 24 h. Further investigation revealed that expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) was greatly increased in Region CS relative to that in Region ECA. The physiological WSS in the carotid artery system was found to stimulate nitric oxide (NO) and prostacyclin (PGI2) release and inhibit endothelin-1 (ET-1) release after 24-h perfusion experiments. The effective permeability (E.P) of fluorescein isothiocyanate (FITC)–dextran 40 kDa in Regions ECA and CS was monitored, and it was found that the turbulence WSS value (in Region CS) was less than 0.4 Pa, and there was a significant increase in the E.P relative to that in Region ECA, in which laminar WSS value was 1.56 Pa. The tight junction protein (ZO-1) production was shown that the low WSS in Region CS induced ZO-1-level downregulation compared with that in Region ECA.ConclusionsThe results suggested that the gelatin-based perfusable, endothelial carotid artery model can be effective for studying the pathogenesis of atherosclerosis by which flow dynamics control the endothelium layer function in vitro.

Endothelium-Dependent Effects of Echinodorus grandiflorus (Cham. & Schltdl.) Micheli Mediated by M3-Muscarinic and B2-Bradykininergic Receptors on Peripheral Vascular Resistance and Its Modulatory Effects on K+ Channels in Mesenteric Vascular Beds.

This work provides the first demonstration that ethanolic extract (EEEG) obtained from Echinodorus grandiflorus leaves (EEEG) and its butanolic fraction (ButFr) has important vasodilatory effects on isolated mesenteric vascular beds (MVBs). First, the EEEG was obtained and a liquid-liquid fractionation was performed. EEEG and its resulting fractions were analyzed by high-performance liquid chromatography. Then, the vasodilatory effects of EEEG and their respective fractions were evaluated. Finally, the molecular mechanisms involved in the vasodilator responses of the EEEG and ButFr were also investigated. EEEG vasodilator response was estimated at ~11 and 18 mm Hg at doses of 0.1 and 0.3 mg, respectively. Moreover, it was found that ButFr was able to induce an expressive dose-dependent vasodilator response in MVBs. The PP reduction values for doses of 0.1 and 0.3 mg were ~10 and 28 mm Hg, respectively. Endothelium removal or inhibition of nitric oxide and prostaglandin synthase (by L-NAME plus indomethacin) inhibited the vasodilatory effects induced by ButFr or EEEG. The peak effect of ButFr and EEEG doses (0.1 and 0.3 mg) was decreased by ~100% (p < 0.001). The association of atropine plus HOE-140 fully inhibited EEEG and ButFr-induced vasodilation (p < 0.001). Moreover, perfusion with nutritive solution containing 40 mM KCl or previous treatment with tetraethylammonium completely blocked vasodilation induced by ButFr (p < 0.001). This study showed that EEEG and its ButFr have important vasodilatory effects by endothelial M3-muscarinic and B2-bradykininergic receptors inducing nitric oxide and prostacyclin release followed by K+ channels activation in the vascular smooth muscle.

Prolonged release of iloprost enhances pulpal blood flow and dentin bridge formation in a rat model of mechanical tooth pulp exposure.

The aim of this study was to investigate the effect of prolonged release of iloprost, a prostacyclin analog, on angiogenesis and dental pulp healing in a rat model of mechanical pulp exposure. The profile of iloprost release from poly (lactic-co-glycolic) acid (PLGA) microspheres was evaluated, and expression of vascular endothelial growth factor (VEGF) mRNA was determined. The molars of rats were subjected to mechanical pulp exposure and 5 different forms of treatment: Ca(OH)2, PLGA (blank), iloprost, and iloprost/PLGA. Blood flow was determined at 0, 3, and 7 days using laser Doppler flowmetry. After 30 days, the tooth specimens were collected, and subjected to micro-CT and immunohistological analysis. The results showed that iloprost release from the microspheres was prolonged for 4 days, and that the treatment increased tooth blood flow for up to 7 days. At 30 days, an increase of mineralized tissue formation and dentin bridge formation was observed in the iloprost and iloprost/PLGA microsphere groups. VEGF expression was significantly increased in the iloprost/PLGA microsphere group relative to the other groups. In conclusion, this PLGA microsphere iloprost delivery system significantly increased dental pulp blood flow in a prolonged manner and increased tertiary dentin formation in this rat pulp injury model. Prolonged prostacyclin release could be a potentially useful approach for regeneration of dental pulp.

Fibronectin modified TiO2 nanotubes modulate endothelial cell behavior.

Cardiovascular disease has become a great threat to the health of mankind; current titanium (Ti) stents fail due to late stent thrombosis caused by the lack of re-endothelialization of the Ti stent. The objective of this study was to design a novel cardiovascular Ti implant with improved surface biocompatibility. TiO2 nanotubes with a diameter of 110 nm were anodized at a constant voltage of 30 V, and fibronectin was immobilized onto the TiO2 nanotubes using polydopamine. The element composition, morphology, and wettability of the different substrate surfaces were characterized by x-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements, respectively, confirming the successful immobilization of fibronectin. In vitro experiments including immunofluorescence staining, Cell Counting Kit-8 (CCK-8), and nitric oxide (NO) and prostacyclin (PGI2) release demonstrate that fibronectin modified TiO2 nanotubes supported cell adhesion, proliferation, and normal cellular functions of human umbilical vein endothelial cells (HUVECs). These methodologies can be applied for future fabrication of cardiovascular stents.

Diabetes modifies the role of prostanoids and potassium channels which regulate the hypereactivity of the rabbit renal artery to BNP.

Diabetic nephropathy is associated with increased risk of cardiovascular disease. B-type natriuretic peptide (BNP) plays an important role in cardiovascular pathophysiology and therapeutics. The aim of the present study was to investigate the influence of experimental diabetes on the mechanisms that regulate the relaxant response of the rabbit renal artery to BNP. Arterial relaxations to BNP were enhanced in diabetic rabbits. Indomethacin enhanced BNP-induced relaxation in control rabbits but showed no effect in diabetic rabbits. BNP-induced release of thromboxane A2 or prostacyclin was not different in both groups of animals. Iberiotoxin had no effect on relaxations to BNP in both groups of animals. Charybdotoxin displaced to the right the concentration-response curve to BNP in both group of animals, and inhibited BNP-induced relaxation only in diabetic rabbits. Glibenclamide did not modify the BNP-induced relaxations in control rabbits, but inhibited it in diabetic rabbits. These results suggest that diabetes induces hypereactivity of the rabbit renal artery to BNP by mechanisms that at least include (1) a reduced vasoconstrictor influence of arachidonic acid metabolites via cyclooxygenase 2, which is not related with changes in thromboxane A2 and prostacyclin release from the arterial wall and (2) a selectively increased modulatory activity of KATP and endothelial IKCa channels.