Validation of the relationship between coagulopathy and localization of hydroxyethyl starch on the vascular endothelium in a rat hemodilution model

Various anticoagulant properties have been associated with hydroxyethyl starch (HES). However, the mechanism remains unclear and it has not been fully considered whether these properties are beyond the dilutional effect itself. The aim of this study was to reproduce the coagulopathy induced by HES and to test the hypothesis that the coagulopathy is caused by endothelial or glycocalyx damage due to localization of HES on the endothelium, which is caused by the high shear viscosity of dilutional blood. Using a rat model, we compared blood coagulability measured by Sonoclot, levels of endothelial and glycocalyx damage markers and coagulation factors, and blood shear viscosity when hemodilution was performed with physiological saline (PS), 6% HES 130/0.4 in PS, and 10% HES 200/0.5 in PS. We also evaluated the localization rates of fluorescently labeled HES on endothelium in the isolated aorta. HES decreased the fibrin gel formation rate more than did PS. HES was shown to cover the endothelium, possibly due to its high shear viscosity, and this mechanism potentially acted to protect, rather than damage, the endothelium and glycocalyx. However, this covering effect may be the cause of coagulopathy due to inhibition of von Willebrand factor secretion from the endothelium.

Vascular interactions of Croton schiedeanus major flavonoids in isolated aortic rings from Wistar rats

Background: Ayanin (3,7,4’-Tri-O-methylquercetin) and 3,7-Di-O-methylquercetin (DMQ) are the main active metabolites isolated by bioguided fractionation from Croton schiedeanus, species known popularly in Colombia as “almizclillo”, which has been studied in experimental models in rats, exerting vasodilator and antihypertensive effects. Also, when the effect of these flavonoids was studied separately, important vasodilation was observed. Objective: To evaluate whether flavonoids from Croton schiedeanus have synergistic vasodilator properties when different combinations are used in isolated aorta rings. Methods: Cumulative concentrations of ayanin (10-8 M - 6x10-5 M or 0.01 μM - 60 μM) were assayed in the absence and presence of an increasing concentration of 3,7-Di-O-methylquercetin (DMQ) (10-8 – 3x10-5 M or 0.01–30 μM) in isolated rings from Wistar rats, pre-contracted with phenylephrine. The concentration-response curve with the maximal effect was compared with that obtained by Croton schiedeanus whole ethanolic extract (10-6 – 3x10-4 g/mL). Also, this combination was assayed in the presence of the nitric oxide synthetase inhibitor L-NAME (10-4 M) and the guanylate cyclase inhibitor methylene blue (10-4 M) to assess the role of the NO/cGMP pathway in this interaction. Results: Ayanin and DMQ display a dual interaction in vascular relaxant response: agonism at higher concentration ranges (10-6 – 3x10-5 M or 1–30 μM) and antagonism at lower concentration ranges (10-8 – 3x10-7 M or 0.01–0.3 μM). The efficacy at the highest concentration was greater than that obtained by the whole extract (Emax: 98.4% vs. 33.9%). This response was decreased but not reverted in the presence of L-NAME and methylene blue. Thus, the vasodilator effect of this combination does not depend entirely on the NO/cGMP cyclic pathway. Conclusion: The combined use of appropriate concentrations of these flavonoids could represent an advantage over Croton schiedeanus whole extract for vasodilator purposes.

Broccoli sprout Sulforaphane affected hemodynamics and aorta myogenic spontaneous rhythmic contraction in sanitized water uptake mice

Drinking seawater erodes water source will lead to hemodynamic changes in cardiovascular system. The erosion affected vascular biomechanics further interrupt the blood supply in arterial network. In this study, we investigated the carotid arterial hemodynamics in salinity water fed mice, and the relative spontaneous contraction of aorta preparation. The biological effect of Broccoli sprout Sulforaphane was assessed in intake hemodynamic changes. Kunming mice were randomly divided into seawater feeding group, seawater + Sulforaphane group, freshwater feeding group, fresh water + Sulforaphane group. After 4 weeks of feeding, the pressure waveforms of common carotid artery were analyzed in vivo. The enhanced common carotid arterial pressures were calculated according to the breakpoint of systolic pressure rising phase. The ejection time was calculated according to the dicrotic notch. In vitro, the isolated aorta biomechanical features were tested on a micro stepping platform. The passive tension and relative myogenic spontaneous contraction were evaluated. The results indicated that in salinity water fed mice heart rate, ejection period were significantly accelerated. The systolic pressure breakpoint of the ascending phase was significantly increased; however, the central aortic pressure augment index was decreased. In vitro study, the isolated aorta preparations indicated remarkable myogenic spontaneous contraction in salinity water fed mice. The spontaneous contraction indicated a significant cycle pattern, the waveform cluster changes regularly in one cycle, maximal amplitude of myogenic autonomic contraction increased significantly. Spontaneous contraction became more active, however cycle duration shortened. In biological effect of Broccoli sprout supplement, Sulforaphane was effective in reducing the heart rate, prolonging ejection period, improving systolic pressure and pulse pressure amplitude in salinity water fed mice. We concluded that long-term salinity water uptake can form a new hypertension model in mice, which can affect the changes of carotid artery hemodynamics and local blood supply. The Broccoli sprout Sulforaphane can improve the high systolic blood pressure and ejection period of artery, and its mechanism needs further study.

Vasorelaxation endothelium-independent of the ethyl acetate phase from aerial parts of Solanum paludosum Moric. envolves channels-calcium L-type blockade

Previous results showed the ethyl acetate phase (SP-AcOEt), obtained from aerial parts of Solanum paludosum, relaxed the aorta isolated in the endothelium-dependent and -independent manner. The vasorelaxant effects of SP-AcOEt was not characterized on aorta rings endothelium-denuded, thus this work aimed to elucidate the mechanisms endothelium-independent vasorelaxation on rat isolated aorta. The aorta was isolated from Wistar rats and mounted in glass baths containing 6 mL of normal Krebs physiological solution with pH at 7.4. The preparation was maintained at 37ºC and bubbled continuously with a mixture of 95% O2 and 5% CO2. Aortic rings were maintained for 1 hour by a resting tension of 1g and next were contracted with phenylephrine after the sustained contraction ACh was added to access the integrity of the endothelium. SP-AcOEt relaxed pre-contracted aorta by KCl-30mM or -80mM in a similar manner, suggesting blockade CaV, but not channel-K+ participating. SP-AcOEt also inhibited the contraction induced by CaCl2 and relaxed pre-contracted aorta by (±)-BayK8644 (EC50 = 16.9±1.3 μg/mL), which confirms the involvement of L-type CaV blockade. SP-AcOEt presented vasorelaxation endothelium-independent that involves L-type CaV blockade.

Rivaroxaban improves vascular response in LPS-induced acute inflammation in experimental models

Rivaroxaban (RVX) was suggested to possess anti-inflammatory and vascular tone modulatory effects. The goal of this study was to investigate whether RVX impacts lipopolysaccharide (LPS)-induced acute vascular inflammatory response. Male rats were treated with 5 mg/kg RVX (oral gavage) followed by 10 mg/kg LPS i.p injection. Circulating levels of IL-6, MCP-1, VCAM-1, and ICAM-1 were measured in plasma 6 and 24 hours after LPS injection, while isolated aorta was used for gene expression analysis, immunohistochemistry, and vascular tone evaluation. RVX pre-treatment significantly reduced LPS mediated increase after 6h and 24h for IL-6 (4.4±2.2 and 2.8±1.7 fold), MCP-1 (1.4±1.5 and 1.3±1.4 fold) VCAM-1 (1.8±2.0 and 1.7±2.1 fold). A similar trend was observed in the aorta for iNOS (5.5±3.3 and 3.3±1.9 folds reduction, P<0.01 and P<0.001, respectively), VCAM-1 (1.3±1.2 and 1.4±1.3 fold reduction, P<0.05), and MCP-1 (3.9±2.2 and 1.9±1.6 fold reduction, P<0.01). Moreover, RVX pre-treatment, improved LPS-induced PE contractile dysfunction in aortic rings (Control vs LPS, Emax reduction = 35.4 and 31.19%, P<0.001; Control vs LPS+RVX, Emax reduction = 10.83 and 11.48%, P>0.05, respectively), resulting in 24.5% and 19.7% change in maximal constriction in LPS and LPS+RVX respectively. These data indicate that RVX pre-treatment attenuates LPS-induced acute vascular inflammation and contractile dysfunction.

Family screening in patients with isolated bicuspid aortic valve in a general hospital, yield and subgroup analysis

Background Bicuspid aortic valve (BAV) may frequently lead to aortic dilatation with risk of aortic dissection. In patients with BAV both familial clustering and aortic dilatation in first-degree relatives (FDR) without BAV has been demonstrated. Based on these findings the ESC Aortic Guidelines recommend to consider screening of FDR, while the ACC/AHA Guidelines on Valvular Heart Diseases consider screening of FDR only if the index patient has associated aortopathy. Currently, no data about the effectiveness of screening is available. Purpose To investigate the yield of screening FDR of patients with isolated BAV and to explore subgroups with FDR of patients who had needed surgery or of patients with aortic dilatation. We hypothesized that aortic dilatation (&gt;40mm) in the index patient is not a risk factor for BAV in FDR. Methods From 2012, patients with BAV visiting the outpatient clinic of a teaching hospital, received information advising cardiac screening of FDR. FDR of patients with isolated BAV who were referred, were included. From the 10 index patients from other hospitals, information was retrieved. [Fig.1] Results Referred were FDR from 118 index patients (mean age 60 years, standard deviation [SD] 14, range 15–90 years, 82 males [70%]). Of all index patients 63 (53%) had undergone aortic valve replacement, including concomitant ascending aorta replacement in 25 (21%). In the non-operated index patients, 31 (26%) had dilatation (&gt;40mm) of sinus of Valsalva and/or tubular ascending aorta. Screened were 257 FDR (median 2 per index patient) comprising 20 parents (8%), 103 siblings (40%) and 134 offspring (52%). Mean age of FDR was 48 years (SD16, range 4–83 years) and 89 subjects (42%) were male. The diagnostic imaging modality was echocardiography in 240 cases (93%) and MRI in 17 cases. Ten FDR had an already known BAV and were not included in the screening. Among the 257 FDR, we diagnosed 12 new BAV (4.7%, 95% confidence interval [CI]2.9–8.0%) (mean age 44 years, 50% male). Additionally, we diagnosed 23 new isolated aorta dilatations (8.9%; 95% CI 6.0–13%) at level of sinus of Valsalva and/or tubular ascending aorta (mean age 57 years, 18 [78%] were male) [Fig. 1]. Among them, 11 had hypertension. FDR (n=147) of index patients with BAV and previous aortic valve surgery (n=63), had a risk ratio (RR) of 2.25 (95% CI 0.62–8.10) of having a BAV. FDR (n=126) of index patients with BAV and repaired or unrepaired aortic dilatation (n=56) had RR 0.35 (95% CI 0.10–1.25) of having a BAV. Conclusions Screening FDR of patients with isolated BAV resulted in a reasonable yield of 14% new cases with BAV or isolated aortic dilatation. The RR of the subgroup with aorta dilatation did not justify the limitation of the FDR as suggested in the ACC/AHA Guidelines. Figure 1. Flowchart of screening and result Funding Acknowledgement Type of funding source: None

Abstract P061: Identification Of Piezo1 Channels In Perivascular Adipose Tissue (pvat) And Their Potential Role In Vascular Function

The vasculature constantly experiences distension/pressure exerted by the blood and responds accordingly to maintain homeostasis. Perivascular adipose tissue (PVAT) is gaining support as a formal blood vessel layer and also experiences these changes. We hypothesized that activation of the mechanotransducer Piezo1 directly increases vascular contraction in a way that might be modified by PVAT. The presence of Piezo1 was investigated at the mRNA level via PCR; protein via immunohistochemistry; and contractility via isolated tissue bath. Rat superior and mesenteric arteries, thoracic aortae, human mesenteric vessels and their PVATs were studied. Piezo1 mRNA (beta2 microglobulin calibrator) was expressed in the aortic vessel (2 -ΔC T =0.011); aortic PVAT (2 -ΔC T =0.0172); mesenteric vessel (2 -ΔC T =.00302), and mesenteric PVAT (2 -ΔC T =0.0219). Both adipocytes (2 -ΔC T =0.0249) and stromal vascular fraction (2 -ΔC T =0.0159) of mesenteric PVAT expressed Piezo1 mRNA. Piezo1 mRNA expression was greater in magnitude (one-way ANOVA) than that of the mechanotransducers Piezo2, TRPV4, TMEM16, and Panx1. Piezo1 protein was present in rat aortic PVAT, rat mesenteric (mes) artery, vein, and PVAT, as well as in human artery, vein, and PVAT. The Piezo1 agonists Yoda and Jedi (1 nM - 10 μM) did not stimulate rat aortic contraction [max <10% phenylephrine (PE) 10 μM contraction] or relaxation independent from vehicle in tissues + or - PVAT (relaxation as % of half maximal PE contraction was: Veh-PVAT=45.3±7.0; Yoda-PVAT=46.7±25.6; Jedi-PVAT= 40.4±10.3; Veh+PVAT= 71.8±19.7; Jedi+PVAT=39.1±13.2; Yoda +PVAT=21.6±10.9). Slightly K+ depolarizing the aorta did not unmask contraction to Yoda. Finally, the Piezo1 antagonist Dooku [10 μM] did not shift the PE curve (-log EC50 values [M]: Veh-PVAT= 7.96±0.12; Dooku-PVAT=7.26±0.22, Veh+PVAT=7.29±0.08; Dooku+PVAT=6.96±0.07). Surprisingly, Dooku [10 μM] directly caused aortic contraction in the absence of PVAT (Dooku 27.2±11.7 vs vehicle 13.5±11.2 %PE contraction), but not in the presence of PVAT vs vehicle (Dooku 2.9±1.9 vs Vehicle 7.3±5.2% PE contraction). Thus, Piezo1 is present and functional in the isolated aorta, important knowledge given that this molecule may serve as a translator of vascular pressure.

Bio-guided Fractionation of the Ethanolic Extract from Leaves of Trema orientalis Blume (Cannabaceae), a Presumed Antihypertensive Plant from Congo-Brazzaville

Hypertension is a risk factor for cardiovascular disease, which is currently a real public health problem. This disease affects about one billion people worldwide and is responsible for more than 70% of cardiovascular related deaths. Recently, the World Health Organization reported that of the hypertensive cases detected in Congo, only 7% were controlled. Today, there is no lifetime treatment and existing drugs are less accessible by the African population. To treat the disease, the Congolese population uses more the medicinal plants. However, the majority of compounds responsible for the biological activity of these plants are not known. In order to bring out Congolese plants with antihypertensive properties, we focus our interest on Trema orientalis Blume (Canabaceae). An ethanolic extract of the leaves of Trema orientalis was prepared after successive depletion of the organic solvents. Thereafter, a bio-guided fractionation on silica gel of the ethanol extract was carried out. Fractionation monitoring was done by TLC and the results of vasodilating activity measured. The fractions exhibiting the best biological activity allowed a second fractionation process to obtain five fractions which are characteristic of polyphenols, in particular flavonoids, and which exhibited good vasodilating activity on the isolated aorta of rats. Our future work will focus on the identification of these biologically active compounds.