bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Arterial Network Structure on Electrical Communication
Authors: Tran Cam Ha T , Vigmond Edward J , Goldman Daniel , Welsh Donald G
Published: June 2021

The basis of electrical communication and its role in regulating vascular tone has have been successfully build on an examination of charge movement in isolated vessel segments. How electrical communication behaves in complex arterial networks remains elusive. The goal of this investigation was to examine the nature of electrical communication in arterial networks and to ascertain how charge distributes within these structures in normal and pathophysiological states. Our analysis began with simulations performed on an existing computational model expanded to form arterial networks ranging from 1–31 vessels. Initial simulations revealed that focal endothelial stimulation generated electrical responses that conducted to a variable degree along an unbranched vessel or across a single branch point depending on the designed structure. These predictions were consistent with observations from the mesenteric arteries and supported the idea that vessel length and branch points influence the conducted response by increasing electrical load. Further expansion of the virtual network to 31 branches revealed that electrical stimuli could ascend into proximal arteries if a sufficient number of distal arteries were simultaneously activated. Additional network analysis centered on the gap junctional conductance changes that occur during sepsis, hypertension and atherosclerosis, highlighted that each disease state uniquely affects electrical communication and consequently the nature of blood flow control. By synergistically employing computational modeling with experimentation, this study becomes the first to address how the physical structure of arterial network and its impact on electrical load influences electrical information in normal and diseased vessels.
A novel approach for imaging calcium events simultaneously in arteriolar vascular smooth muscle and endothelial cells
Authors: Bagher Pooneh , Garland Christopher J. , Dora Kim A.
Published: June 2021

Increases in global calcium within vascular smooth muscle (VSMCs) and endothelial cells (ECs), which are crucial for the modulation of myogenic tone in resistance arterioles, have traditionally been examined independently. We have developed a novel method to simultaneously examine changes in VSMC and EC calcium event frequency to various stimuli. Second‐order cremasteric arterioles isolated from adult male Wistar rats were mounted on glass cannulation pipettes and secured with sutures. Vessels were heated, pressurized, developed myogenic tone, then functionally tested. VSMCs and ECs were loaded with Oregon Green‐488 BAPTA‐1 and imaged simultaneously along the midline of the arteriole using multi‐photon microscopy at 3Hz. The frequency of spontaneous calcium events was examined under high and low luminal pressure and in the presence of phenylephrine (PE). Calcium event frequency increased in VSMCs at high pressure versus low, while the opposite relationship was observed in ECs. The frequency of EC calcium events increased significantly to PE while only the amplitude increased in VSMCs. Using this novel method, we are able to assess calcium events simultaneously in VSMCs and ECs and have demonstrated that opposing spontaneous calcium events occur in these cells at high and low pressure, while the agonist PE induces a unique calcium event profile. This work is supported by a Wellcome Trust Programme grant.
A Functional Role for N‐cadherin in Mediating Mechanotransduction in Arteriolar Vascular Smooth Muscle Cells
Authors: sun zhe , Li Zhaohui , Meininger Gerald A.
Published: June 2021

A hybrid atomic force (AFM)‐confocal microscopy system was used to examine whether mechanical forces applied through N‐cadherin adhesions on vascular smooth muscle cells (VSMC) could induce i) cellular contraction and ii) signaling events. AFM probes were modified by attaching a borosilicate microsphere (5 μm) to the tip and coating with either 1) a recombinant N‐cadherin chimera fusion protein (rhNcad), or 2) an N‐cadherin antibody; or 3) attaching a live VSMC to the end of the AFM cantilever. In all 3 cases, a strong adhesion was formed between the AFM probe and cell membrane; and AFM pulling forces (~1000 pN) induced a strong VSMC contractile response that pulled the probe oppositely. In addition, clustering of N‐cadherin‐GFP and RhoA‐GFP was observed when an rhNcad coated AFM probe was engaged on the VSMC membrane, and application of AFM pulling force enhanced the clustering. Immuno‐fluorescence labeling showed a dramatic increase of N‐cadherin clustering in the vessel wall of pressurized arterioles that developed spontaneous myogenic tone compared to unpressurized vessels, as well as spatial correlations between the N‐cadherin and the clusters of active RhoA, myosin II and the phosphorylated myosin phosphatase targeting subunit. Collectively, these results support an important role for N‐cadherin in mediating the myogenic mechanotransduction in VSMC. (AHA 0835676N to Z.S. and NIH P01HL095486 to G.A.M.)
Temporal relationship between inflammation‐induced lymphangiogenesis and angiogenesis in rat mesenteric microvascular networks
Authors: Sweat Richard Shelton , Stapor Peter Conrad , Murfee Walter Lee
Published: June 2021

The interrelationship between lymphangiogenesis and angiogenesis remains under‐investigated. The objective of this study was to compare the temporal dynamics of lymphatic and blood vessel growth post inflammatory stimulus in the rat mesentery. Mesenteric tissues were harvested from unstimulated adult male Wistar rats and at 3 and 10 days post compound 48/80 stimulation (n=4 animals, 7 tissues per group). Tissues were labeled with antibodies to PECAM, LYVE‐1, and class III β‐tubulin. Angiogenesis was confirmed by increased vascular area per tissue area at 10 days. Blood capillary sprouting increased at day 3 and remained elevated at day 10. Over the 10 day time course, lymphatic vascular area remained comparable. Lymphatic sprouting increased at day 3 and continued to increase through day 10. The peak in lymphatic sprouting correlated with the presence of class III β‐tubulin positive endothelial cells along lymphatic blind ended vessels. Our results establish 48/80 stimulation as a model of lymphangiogenesis in the rat mesentery. While lymphangiogenesis occurs in concert with angiogenesis, the peak in lymphatic sprouting apparently lags blood capillary sprouting. Class III β‐tubulin upregulation during the peak of lymphatic sprouting implicates it as a novel marker of lymphangiogenesis. Supported by the Board of Regents of the State of Louisiana LEQSF(2009‐12)‐RD‐A‐19.

Grant Funding Source : Board of Regents of the State of Louisiana LEQSF(2009‐12)‐RD‐A‐19
Sustained High Luminal Flow In Vivo Decreases Maximal Developed Tension of Bovine Mesenteric Lymphatic Vessels
Authors: Nguyen Tam L , Dongaonkar Ranjeet M , Hardy Joanne , Laine Glen A , Quick Christopher M , Stewart Randolph H
Published: June 2021

Although lymphatic function is critical to edema resolution within hours or days, most in vitro studies have been focused on the acute effects of transmural pressure and luminal flow on lymphatic contractility. We have shown that lymphatic vessel function adapts to chronic elevation of microvascular pressure; however, the biomechanics of a contracting lymphatic vessel in response to a prolonged increase in luminal flow has not been characterized. Because lymphatic vessel pumping is inhibited by acute increases in flow, we hypothesized that lymphatic vessels exposed to sustained high luminal flow will decrease developed tension. Sustained mesenteric hypertension was created in adult beef cows by occluding a mesenteric vein for 3 days. On day 3, isometric length‐tension relationships of associated mesenteric lymphatic vessels were obtained with a novel tubular organ bath that can maintain both constant luminal volume and luminal flow. While diastolic tension was not different between hypertensive (MVH) and control group (SHAM), there was a significant decrease in systolic tension in MVH at all circumferential lengths. As a result, active tension of MVH was significantly lower than SHAM. We conclude that in response to sustained high luminal flow, lymphatic vessels decrease muscle contractility by decreasing systolic tension without changing diastolic properties. (Supported by NIH and AHA grant)
Interplay between NO, prostaglandins and KATP channels in the lymphatic pumping dysfunction observed during experimental intestinal inflammation
Authors: von der Weid Pierre-Yves , Mathias Ryan , Rehal Sonia
Published: June 2021

Lymphatic vessels rhythmically contract to actively propel lymph. This function, critical to tissue fluid homeostasis and immune cell trafficking is impaired in Crohn's disease and in the guinea‐pig model of TNBS ileitis, suggesting compromised lymph flow and lymphatic vessels potential players in the disease. Nitric oxide (NO) and prostaglandins (PGs), abundantly produced during intestinal inflammation, are known to activate ATP‐sensitive potassium (KATP) channels expressed in lymphatic muscle. Our aim was to assess the role of KATP channels, NO and PGs in inflammation‐induced lymphatic pumping dysfunction.

After induction of intestinal inflammation, mesenteric lymphatics were collected for qPCR analysis, or isolated to assess their contractile and electrophysiological properties.

Expression of mRNA for KATP channel subunits Kir6.1 and SUR2B, nitric oxide synthase iNOS and cyclooxygenase COX2 was significantly upregulated in lymphatics from TNBS‐compared to sham‐treated animals. Vessels from TNBS‐treated animals were dilated, quiescent, with strongly hyperpolarized muscle. Administration of the KATP blocker glibenclamide, iNOS inhibitor 1400W and COX inhibitor indomethacin restored pumping and depolarized lymphatic muscle.

Our findings suggest that NO and PGs mediate lymphatic contractile dysfunction seen in TNBS‐treated animals via KATP channel opening.

Supported by CIHR
TNF‐α mediated regulation of myosin light chain 20 phosphorylation in lymphatic muscle
Authors: Zawieja Scott D , Wu Xin , Chakraborty Sanjukta , Muthuchamy Mariappan
Published: June 2021

We have shown that mesenteric collecting lymphatic vessels isolated from rats with a high fructose induced metabolic syndrome (MetSyn) exhibit a 50% reduction in force generating capacity and reduced calcium sensitivity. We hypothesized that the elevated level of the inflammatory cytokine TNF‐α associated with MetSyn contributes to the mesenteric lymphatic force reduction. Rat mesenteric lymphatic muscle cells (RMLCs) were cultured in the presence of varying amounts of TNF‐α for 1, 24, and 96 hours, and the basal phosphorylation of myosin light chain 20 (MLC20), an indicator for lymphatic muscle contraction was assessed. We found that chronic TNF‐α (20ng/ml) stimulation significantly reduced phospho‐MLC20 to MLC20 ratio in the basal state at 96 hrs while they were unchanged in 1 and 24 hour treated cells. Furthermore chronic stimulation of RMLCs with lipopolysaccharide recapitulated the results from chronic TNF‐ α exposure. We propose that lymphatic muscle force generation capacity reduced in MetSyn animals is partially due to inflammation‐mediated MLC20 phosphorylation regulation. Our data suggest a potential mechanism whereby elevated endotoxin translocation associated with an increase in TNF‐α contribute to the reduction in force production and calcium sensitivity in mesenteric lymphatic vessels of MetSyn animals. Supported by NIH HL86650 to MM; AHA09POST2280005 to SC.
Mechanism and subpopulation specificity of mitochondrial ROS release in the post‐ischemic hyperthyroid myocardium
Authors: de Mooy Anthony Bret , Le Catherine H , Harcy L Victoria , Chicco Adam J
Published: June 2021

Hyperthyroidism (HT) augments release of reactive oxygen species (ROS) from cardiac mitochondria following myocardial ischemia/reperfusion (I/R). The present study examined the mechanisms of this phenomenon and determined whether subsarcolemmal (SSM) and intermyofibrillar mitochondria (IFM) are differentially affected. Male SD rats received 10 daily injections of thyroid hormone (30ug/kg i.p.; HT) or vehicle (CON) before hearts were excised and exposed to a 20/25 min global I/R protocol ex vivo. Following I/R, ROS release was assessed in freshly isolated SSM and IFM using the Amplex Red assay with a variety of substrate and inhibitor combinations to examine sites and mechanisms of release. ROS release from SSM exceeded IFM in CON and HT hearts by 25–50% following I/R (P < 0.01). Surprisingly, HT augmented ROS release from SSM, but decreased ROS release from IFM (P < 0.05 for both). Blocking electron flow from respiratory complex 1 to 3 abolished the effect of HT on SSM, but not IFM. Inhibition of uncoupling proteins with GDP abolished the HT‐induced reduction in IFM, but had little effect in SSM. Maximally uncoupling mitochondria with FCCP abolished effects of HT in IFM and SSM. Collectively, results indicate that 1) complex 3 in SSM is the primary source of mitochondrial ROS release following I/R in HT, and 2) enhanced activity of uncoupling proteins limits ROS release from IFM under these conditions. Funding: NHLBI
Diabetic genetic background does not influence the isoflurane preconditioning in human cardiomyocytes differentiated from induced pluripotent stem cells derived from a type 1 diabetes patient
Authors: Kikuchi Chika , Canfield Scott , Bai Xiaowen , Koopmeiners Andrew , Kwok Wai-Meng , Schaefer Richard , Bosnjak Zeljko
Published: June 2021

Anesthetic preconditioning (APC) has been proved to increase myocardial tolerance to ischemia reperfusion injury. However, growing evidence shows that APC is attenuated in diabetes. The generation of induced pluripotent stem cells (iPSCs) enabled the production of patient specific cardiomyocytes (CMs), providing a novel model to study the roles of diabetic genetic background and environmental factors in the attenuation of APC. iPSCs generated from a healthy donor and a T1DM patient were directly differentiated into CMs (N‐iPSC‐CMs and T1DM‐iPSC‐CMs, respectively). The differentiated CMs were confirmed by the expression of CM‐specific markers troponin T and sarcomeric á‐actinin and the presence of action potentials. Lactate dehydrogenase (LDH) release assay was then performed to determine the viability with or without isoflurane preconditioning in response to oxidative stress. The isoflurane preconditioning decreased LDH release in both N‐iPSC‐CMs and T1DM‐iPSC‐CMs in response to oxidative stress.

iPSCs generated from both the healthy donor and the T1DM patient can differentiate into functional cardiomyocytes. Importantly, our results show that isoflurane can precondition both N‐iPSC‐CMs and T1DM‐iPSC‐CMs, suggesting that genetic factors may not play major roles in the attenuation of APC. P01GM066730 and R01HL034708 from the NIH, Bethesda, MD (to Z. Bosnjak).
Ethanol preconditioning protects against ischemia/reperfusion‐induced cardiac damage via calcitonin gene‐related peptide and is initiated by a transient receptor potential vanilloid 1‐dependent mechanism
Authors: Wang Meifang , Zuidema Mozow Y. , Korthuis Ronald J.
Published: June 2021

Our previous studies indicated that ingestion of ethanol at low to moderate levels prior to ischemia/reperfusion (I/R) protects against postischemic intestinal and cerebral injury. These protective actions are initiated by a calcitonin gene‐related peptide (CGRP)/ transient receptor potential vanilloid 1 (TRPV1) ‐ dependent mechanism. This study was to determine whether a similar mechanism underlies the protective effect of ethanol preconditioning in cardiac I/R injury. Serum Troponin‐I (cTnI), a marker of myocardial injury, was markedly elevated in wild type male C57BL/6J mice after 30 min left anterior descending (LAD) ischemia and 4 h reperfusion, at which cTnI reaches its peak level. When mice were treated with ethanol 24 h prior to cardiac I/R as a bolus by gavage (at a dose that produces peak plasma ethanol of 40–45 mg/dl), cTnI levels did not increase in comparison to I/R alone (p<0.001). This protective effect of ethanol consumption was significantly attenuated by administration of capsazepine, a competitive TRPV1 antagonist 10 min before ethanol ingestion (p<0.05). These findings demonstrate the protection against cardiac I/R from antecedent ethanol ingestion occurs via a TRPV1‐dependent mechanism. Supported by a grant from the NIH (AA‐014945).
Superficial Nephrons in BALB/c Mice Facilitate in vivo Multiphoton Imaging
Authors: Schießl Ina , Castrop Hayo
Published: June 2021

Renal glomerular structure and function can be evaluated in vivo by the use of multiphoton microscopy (MM). The method however is limited by the tissue penetration depth of the excitation laser, which is in the range of 130 μm for the kidney. In view of the relevance of gene‐targeted mice for MM studies, we aimed to identify a mouse strain with a high percentage of superficial glomeruli. The average depth of (i) the most superficial glomeruli per animal and of (ii) all glomeruli within 200 μm from the kidney surface was determined in commonly used mouse strains. The depth of the 30 most superficial glomeruli per animal averaged 190±5, 128±4, 165±5, 136±7, 212±5, 117±2, 116±5, 109±3, 149±4, and 148±5 μm in kidney sections from 4‐week‐old 129/Sv, C57BL/6N, CB6F1, C3H/HeN, NMRI, SJL, DBA/2N, BALB/c, FVB, and CD‐1 mice, respectively (3 animals; p<.0001 for BALB/c vs. average of all strains). BALB/c and DBA/2N were the only strains with a 25% percentile below 100 μm (p<.0001 vs. average of all strains). A similar ranking was obtained when all glomeruli within 200 μm from the kidney surface were analyzed. In 10‐week‐old mice, the average of the 30 most superficial glomeruli was located deeper in the cortex, with BALB/c being the only strain with a 25% percentile below 115 μm. In summary, due to many superficial glomeruli, the BALB/c strain appears to be particularly suitable for the investigation of glomerular function using MM.
Effects Of Circulating C‐Reactive Protein Levels On EPC Function
Authors: Nissen Benjamin , Fasing Kevin , Greiner Jared , Stauffer Brian , DeSouza Christopher
Published: June 2021

In vitro, C‐reactive protein (CRP) impairs endothelial progenitor cell (EPC) function; however, the influence of CRP on EPCs in vivo is unclear. We determined whether EPC function is impaired in adults with elevated plasma CRP concentrations, independent of other risk factors. EPCs were harvested from 75 adults (43 males, 32 females): 25 with low CRP (< 1.0 mg/L); 25 with moderate CRP (1.0–3.0 mg/L); and 25 with high CRP (> 3.0 mg/L). The capacity of EPCs to form colonies (colony assay), migrate (Boyden chamber), release angiogenic growth factor (ELISA) and resist apoptosis (active caspase‐3) was determined. There were no significant differences between the CRP groups in EPC colony formation (CFU), migration (AU) or the ability to release vascular endothelial growth factor (VEGF; pg/mL): low (13±3 CFU; 1255±100 AU; 126±24 pg/mL, respectively); moderate (11±3; 1137±85; 97±14); and high (13±4; 1071±80; 119±22) CRP. Staurosporine‐stimulated activation of caspase‐3 was also similar between the low (2.3±0.2 ng/mL), moderate (2.1±0.3 ng/mL), and high (2.2±0.2 ng/mL) CRP groups. These results indicate that elevations in plasma CRP are not associated with impaired EPC function. The negative in vitro effects of CRP on EPCs may be due to the contamination of commercially available CRP preparations with lipopolysaccharide and/or azide preservatives or the use of supraphysiological CRP concentrations.
Thermal burn injury induced myeloperoxidase changes in murine obesity model
Authors: Papineni Rao V , Orton Sean , Vizard Douglas , Geldolph Benjamin
Published: June 2021

Inflammatory response due to thermal burn injury was assessed in murine obesity model. Multimodal non invasive imaging of the myeloperoxidase activity was determined for the purpose. Myeloperoxidase (MPO), an inflammatory heme protein is present in myeloid cells‐ neutrophils, microglia, and macrophages, and utilizes hydrogen peroxide to generate reactive oxygen species. We earlier demonstrated using multimodal fluorescence imaging, infiltration of the peritoneal macrophages at the site of burn injury. Here, we determined the changes in MPO activity as a response to burn injury using C57BL/6NTac mice placed under high fat or regular diet. The in vivo MPO activity was detected by whole body luminescence imaging 15 minutes after i.p injection of luminol. luminol a redox‐sensitive compound emits blue luminescence upon exposure to oxidizing agents, and established to have unique specificity to MPO in vivo. We show significant increase in MPO activity as a result of neutrophil activation at the burn injury. Robust activation, deduced from the MPO activity, was observed in the lymph nodes of the murine model that went through the high‐fat diet regime. These real‐time monitoring methodologies of MPO activity detection by in vivo imaging will greatly enhance the understanding of the early phase of immune response to a burn injury and aid in development of better treatments.
Enhanced Membrane Raft‐Redox Signaling Associated with NADPH Oxidase in Coronary Arterial Endothelium during Hypercholesterolemia
Authors: Wei Yu-Miao , Zhang Yang , Boini Krishna M. , Li Pin-Lan
Published: June 2021

Membrane raft (MR)‐redox signaling platforms associated with NADPH oxidase (NOX) are involved in coronary endothelial dysfunction upon various injury factors. Statins inhibited oxidized low‐density lipoprotein‐induced MR clustering and NOX aggregation and activation in these MR clusters in endothelial cells. The present study tested whether the formation of MR‐redox signaling platforms is enhanced in the coronary arterial endothelium in hypercholesterolemic mice and whether statins block such MR‐redox signaling to protect mice from hypercholesterolemia (HC)‐induced injury. Poloxamer 407 (P407) was administrated i.p. (0.5 g/kg) to induce acute HC in mice, which were also intragastricaly fed pravastatin (140 mg/kg/d), simvastatin (70 mg/kg/d), or vehicle for 7 d. P407 caused a 9.8‐fold increase in plasma cholesterol concentration in mice receiving vehicle treatment, while pretreatment of mice with both statins decreased this P407‐induced cholesterol elevation by 64%. In the coronary arterial intima of mice with acute HC, confocal microscopy demonstrated a co‐localization of gp91phox, p47phox, acid sphingomyelinase or ceramide within MR clusters. Such co‐localization was rarely observed in arteries of normal mice and significantly reduced by pretreatment of mice with statins. Confocal microscopy of dihydroethidium fluorescence also demonstrated that O2•− production in situ was 3 folds higher in the coronary arterial intima of HC mice than that in normal mice, which was inhibited by statins. Taken together, our results indicate that HC enhanced the formation of MR‐redox signaling platforms associated with NOX and that blockade of this MR redox signaling in the coronary endothelium may contribute to the therapeutic effect of statins in preventing endothelial injury and atherosclerosis (supported by NIH grants, HL‐091464, HL57244 and HL‐75316).
Expression of recombinant canine sFlt1 as an experimental anti‐angiogenic agent
Authors: Payne Laura B. , Herring Ian P. , Huckle William R.
Published: June 2021

Formation of new blood vessels is regulated by pro‐ and anti‐angiogenic factors, including VEGF and its secreted receptor sFlt1. With the goal of evaluating sFlt1 as a therapeutic for ocular diseases in dogs, we undertook the generation of recombinant canine sFlt1 (rcsFlt1) protein. Canine sFlt1 coding sequence was recovered as recombinant baculovirus after transfection into Sf9 cells. rcsFlt1 proteins were purified from infected Sf9 conditioned media by adsorption to heparin‐agarose and resolved by SDS‐PAGE. Immunoblotting of heparin‐purified conditioned medium revealed rcsFlt1 of predicted molecular weight (~115 kDa). rcsFlt1 migrated on SDS‐PAGE as a species apparently larger than recombinant mouse sFlt1 similarly produced. Endoglycosidase treatment of canine and mouse rsFlt1 reduced both to co‐migrating species of ~80 kDa, consistent with their predicted primary structures. This result, together with the presence of more predicted N‐glycosylation sites on canine than mouse sFlt1, suggests that differential glycosylation accounts for differential migration of canine and mouse forms. Future studies will examine the topical tolerability of purified rcsFlt1 on canine eyes. Supported by VMRCVM RGS
Imaging of Single Fluorescent Cells for 3‐D Quantification of Neovascularization in Ischemic Myocardial Tissue
Authors: Hakimzadeh Nazanin , van Horssen Pepijn , van den Wijngaard Jeroen PHM , Piek Jan J , Spaan Jos AE , Verberne Hein J , Siebes Maria
Published: June 2021

By employing high‐resolution three‐dimensional (3D) imaging, we aim to detect and quantify monocytes targeting active sites of neovascularization in ischemic myocardium. As a first step, distinguishing exogenously administered cells from highly autofluorescent myocardial tissue and vascular casting material must be addressed. The aim of this study was to optimize visualization of single fluorescent cells with an imaging cryomicrotome.

Human vascular endothelial cells (HUVECs) labeled with CellTrackerTM Orange CMTMR (5, 10, 25 and 72μM) were infused into postmortem coronary arteries of rat and rabbit hearts together with replica resin (Mercox) containing fluorescent dye (Potomac Yellow or UV Blue). Following polymerization of replica resin, hearts were frozen at −20ºC and further processed with the imaging cryomicrotome.

In 3D reconstructions of hearts cut at 5μm slice thickness, HUVECs labeled with dye concentrations higher than 5μM were visible in the presence of UV Blue cast material, while cells labeled with 72μM dye demonstrated superior brightness.

The successful identification of single exogenously administered cells in the presence of vascular cast material will allow quantification of actively growing collaterals which recruit monocytes in ischemic myocardial tissue.

Supported by the Center for Translational Molecular Medicine (EMINENCE) and the Netherlands Heart Foundation
The Importance of Aquaporin 1 for Vascular Smooth Muscle Cell Migration after Vascular Injury
Authors: Stubbe Jane , Johansen Soeren Hoeyer , Jensen Boye L.
Published: June 2021

Restenosis is one of the major complications after percutaneous coronary intervention (PCI). A newly discovered candidate necessary for vascular cell migration is the water channel aquaporin 1 (AQP1). In mice, lack of functional AQP1 limits tumor expansion by decreased endothelial cell migration within the growing tumor. AQP1 has been localized in neointima vascular smooth muscle cells after wire induced vascular injury in rats. Thus, we hypothesized that AQP1 is important for vascular smooth muscle cell migration and neointima formation after PCI. We tested this by performing wire‐induced vascular injury in the femoral artery in mice with and without functional AQP1 gene. 28 days after surgery the femoral arteries were isolated and 10 consecutive cross sections of the femoral artery 100 ìm apart were stained with Verhoeff‐ van‐Giesson and analyzed for neointima formation, media area, intima to media ratio, and for vascular stenosis. We found no statistically significant difference in neointima formation (41260 ±15150 (WT) vs. 25110 ± 7614 μm2 (AQP1−/−)), or in media area (27240 ± 2748 vs. 21890 ± 3019 μm2, p<0.22), or in intima–to‐media ratio (1.3 ± 0.4 vs. 1.9 ± 0.9), or in percent vascular stenosis (50 ± 17% vs. 42 ± 13%) between femoral arteries after injury from mice with functional versus non‐functional AQP1 gene, respectively. Thus we can conclude that AQP1 does not contribute to neointima formation in mice.
Variation in kidney oxygenation: towards long‐term recording by telemetry
Authors: Koeners Maarten , Ow Pei , Abdelkader Amany , Papazova Diana , Verhaar Marianne C. , Evans Roger G. , Russell David M. , Joles Jaap A. , Malpas Simon
Published: June 2021

Recently we developed a telemetry‐based carbon paste oxygen electrode (CPE) which can record kidney oxygenation in rats, unhindered by anesthesia or restraint. To test this new modality we first measured renal oxygen in anesthetised control and subtotaly nephrectomized (SNx) rats while varying inspired oxygen. Second, renal oxygen was measured before, during and after ischemia induced by a vascular clamp. Third, a fully implantable telemetry system was used for recording 3 weeks before and 1 day after ischemia. The CPE could easily detect changes in renal oxygen upon step‐wise increments and decrements of inspired oxygen, while renal perfusion pressure and blood flow remained unchanged from baseline. Kidney oxygenation was lower and less responsive to changes in inspired oxygen in SNx compared to controls. Telemetry‐based CPE could successfully measure renal oxygen before, during and after ischemia. Realisation of a telemetry‐based oxygen sensor, capable of long‐term monitoring of relevant perturbations, will enable us to elucidate links between renal oxygenation and kidney health. EU, FP7, Marie Curie Actions, International Outgoing Fellowship.
Functional cardiovascular responses precede structural responses to enhanced blood pressure variability
Authors: Rarick Kevin R , Klepper Kayla M , Nash Abigail L , Rotella Diane L , Stauss Harald M
Published: June 2021

Clinical studies demonstrated that enhanced blood pressure variability (eBPV) leads to cardiovascular damage even in normotensive subjects. We investigated the time course of functional and structural cardiovascular responses to eBPV in normotensive rats over a time period of 6 weeks following sinoaortic denervation (SAD, n=6) or Sham surgery (n=4). Six weeks after SAD surgery mean blood pressure (BP) remained normotensive, systolic BP variance was increased by 210±80% (P<0.05), and baroreflex sensitivity was lower by 32±3% (P<0.05) compared to Sham. Weekly in vivo assessment of endothelial function of the long posterior ciliary artery demonstrated a significant reduction in pilocarpine‐induced vasodilation starting at 4 weeks after SAD surgery (62±14%, P<0.05). Endothelial‐independent relaxation was not affected by SAD. Echocardiography revealed a 53±7% (P<0.05) lower aortic distensibility after only 1 week of SAD compared to Sham. Six weeks after SAD, left ventricular (LV) cardiac contractility (dP/dtmax) was reduced by 45±15% and LV end‐diastolic pressure was increased by 25±5% compared to Sham (P<0.05). Cardiac weight and aortic wall thickness tended to be increased (P<0.1). These data indicate that eBPV induces endothelial dysfunction associated with impaired cardiac function in less than six weeks, while vascular and cardiac structural changes only start to appear after 6 weeks of eBPV.
Effects of Fresh and Aged Vehicular Particulate Emissions on Blood Pressure in Normal Adult Male Rats
Authors: Lamoureux Denise Paige , Diaz Edgar A , Coull Brent A , Papapostolou Vasileios , Lawrence Joy , Sato Rodrigo , Godleski John J
Published: June 2021

BACKGROUND

Associations between exposure to fine particulate matter (PM2.5) and blood pressure (BP) have been inconsistent in epidemiologic studies.

OBJECTIVES

We used a unique exposure system to separate traffic‐derived PM2.5 into primary and secondary components to measure effects on BP.

METHODS

Sprague Dawley rats were repeatedly exposed to primary only (P), secondary organic aerosol only (SOA), a combination of the two (P+SOA) or filtered air for 5‐hours/day for 3 weeks. Exposure dose was ~50 μg/m3. BP was measured continuously using implanted telemetry. Mixed effects models were used to compare responses of systolic (SBP), diastolic blood pressure (DBP) and heart rate (HR).

RESULTS

Exposure to P increased and maintained an effect on SBP and DBP across weeks showing a significant dose response. SOA exposure on the first day resulted in a significant increase in both SBP and DBP (p=.001, p=.0003) becoming strongly negative by week 3. With P+SOA, significant increases in SBP and DBP of 13 mmHg were observed on the first day of exposure (p=.04, p=.0015) which was maintained through week 1 for SBP and through week 2 for DBP. Sham exposures in the SOA and P+SOA groups after 3 weeks showed compensatory decreases in both SBP and DBP. No exposure had a significant effect on HR.

CONCLUSIONS

Both primary and secondary traffic derived aerosols can substantially increase SBP and DBP but these increases are eventually lost.
NTS (pro)renin receptor (PRR)‐mediated antihypertensive effect involves NF‐KappaB‐cytokine signaling in the spontaneously hypertensive rats (SHR)
Authors: Zubcevic Jasenka , Jun Joo Yun , Lamont Gwyneth , Murca Tatiane , Shi Peng , Carvajal Jessica Marulanda , Lin Fan , Li Qiuhong , Raizada Mohan K , Shan Zhiying
Published: June 2021

Increased PRR expression in the NTS of SHR, coupled with the evidence on role of the brain inflammation in cardiovascular functions, has led us to hypothesize that the NTS PRR may play a part in blood pressure (BP) regulation by modulation of the brain inflammatory pathways. Acute NTS injections of renin (0.02–2 pmol) resulted in a significantly greater dose‐dependent decrease in systolic BP (ΔSBP; −12±5 to −32±5 mmHg) and heart rate (ΔHR; −13±7 to −40±10 bpm) in the SHR compared to the WKY rats (ΔSBP: −3±1 to−8±4 mmHg; ΔHR: −2±4 to −12±7 bpm). These effects were not blocked by the AT1R or AT2R blocker. Consistent with this, chronic PRR knockdown with AAV2‐PRR‐shRNA in the SHR NTS caused an increase in mean arterial pressure (shRNA: 173±5; Control: 151±6 mmHg), and decreases in baroreflex bradycardia (shRNA: 0.26±0.04; Control: 0.44±0.04) and parasympathetic tone (shRNA: 31±4; Control: 49±6). This was accompanied by a decrease in the inflammatory markers TNFa, IL6 and Ccl5, and their transcription factors, NF‐κB and AP‐1. Finally, PRR activation in the SHR brain neuronal cultures activated NF‐κB, and increased the mRNA of IL1β (250 fold), TNFα (32 fold), IL6 (35 fold) and Ccl5 (12 fold) in an NF‐κB‐ and AP1‐dependent, but AT1R/AT2R‐independent manner. Therefore, the NTS PRR mediates Ang II‐independent antihypertensive effects by stimulation of NF‐κB/AP‐1/cytokine signaling (AHA 11SDG7420029)
Impaired Baroreflex Sensitivity in Anabolic Steroid Users
Authors: dos Santos Marcelo Rodrigues , Porello Rafael Armani , Sayegh Ana L C , Hong Valeria , Toschi-Dias Edgar , Bortolotto Luiz A , Yonamine Mauricio , Negrao Carlos E , Alves Maria-Janieire N N
Published: June 2021

Purpose

Exacerbated sympathetic nerve activity and increased blood pressure have been documented in anabolic androgenic steroid users (AASU). We tested the hypothesis that arterial baroreflex sensitivity (BRS) and carotid distensibility would be reduced in AASU.

Methods

Ten AASU and 10 age‐paired anabolic androgenic steroid nonusers (AASNU) were studied. Both groups were involved in strength training (90% 1MR) and AASU were self‐administered anabolic steroids for at least 2 years. The use of AAS was proved by urine. Heart rate (HR) was evaluated by EKG and blood pressure non‐invasively on a beat to beat. BRS was analyzed by time domain through spontaneous fluctuations between systolic blood pressure (SBP) and HR. Carotid artery distensibility was measured by doppler (M‐mode).

Results

HR was higher in AASU compared to AASNU (69±3 vs. 59±3 bpm, P≤0.05). Systolic (123±4 vs. 118±2 mmHg, P=0.29), diastolic (72±2 vs. 67±2 mmHg, P=0.12) and mean blood pressure (90±3 vs. 85±2 mmHg, P=0.15) were not different between groups. BRS for increases (14.2±2 vs. 22.8±3 msec/mmHg, P=0.05) and decreases (13.3±1 vs. 19.2±2 msec/mmHg, P=0.04) were lower in AASU. Carotid distensibility was reduced in AASU (7±1 vs. 9±1 %, P≤0.05).

Conclusion

Impaired BRS and reduced carotid distensibility may prematurely lead to increased cardiovascular risk in AASU.
Baroreflex sensitivity is associated with blood pressure transients in young men but not young women
Authors: Matzek Luke J , Hart Emma C , Charkoudian Nisha , Joyner Michael J , Curry Timothy B , Barnes Jill N
Published: June 2021

Baroreflex sensitivity is calculated from the slope of the relationship between blood pressure and muscle sympathetic nerve activity (MSNA) or cardiac R‐R interval. The magnitude of decrease in blood pressure during a vasoactive drug bolus (i.e. modified Oxford) to test the baroreflex may be associated with the calculated baroreflex sensitivity (BRS) slope. We investigated whether the cardiac or sympathetic BRS are associated with the acute decrease in blood pressure during a modified Oxford in young healthy men and women. Forty‐five women (27 ± 1 yrs, BMI 22.9 ± 0.3 kg/m2) and 30 men (27 ± 1 yrs, 24.2 ± 0.4 kg/m2) were studied. MSNA was measured via peroneal microneurography and blood pressure was measured with a brachial intraarterial catheter. Women and men had similar mean arterial pressures (91 ± 1 vs. 90 ± 1 mmHg), cardiac BRS (19 ± 1 vs. 21 ± 2 ms/mmHg), and sympathetic BRS (−6 ± 0.4 vs. −7 ± 0.6 AU/beat/mmHg), respectively. The decrease in systolic blood pressure (SBP) and pulse pressure (PP) was positively related to cardiac BRS in men (r=.47; p<0.01; r=.49; p<0.01). However, there was no relationship between the decrease in blood pressure and sympathetic BRS in men. In addition, there was no association between any blood pressure transients with either cardiac or sympathetic BRS in women. Our results suggest the magnitude of decrease in blood pressure is associated with cardiac BRS in men, but not women.

Funded by NIH
Cerebral autoregulation in humans: role of the myogenic mechanism
Authors: Hamner Jason W. , Tan Can Ozan , Taylor J. Andrew
Published: June 2021

Myogenic mechanisms have been hypothesized to account in part for cerebral autoregulation. Previous work in rats and more recent work in humans provide equivocal results. The animal data suggests that myogenic mechanisms are active at frequencies below 0.1 Hz. In contrast, the human data suggests that myogenic mechanisms are less important at these frequencies, but this was assessed using lower body negative pressure at levels beyond the threshold for syncope. Therefore, we examined cerebral blood flow responses to augmented arterial pressure oscillations with and without Ca2+ channel blockade (nicardipine) across a range of frequencies (0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 Hz) and with levels of oscillatory lower body negative pressure (OLBNP) well below the threshold for syncope in humans (30 mmHg) in 16 healthy subjects. Ca2+ channel blockade resulted in an increase in mean pressure and heart rate, but decreased cerebral flow. Despite these hemodynamic changes, the transfer function relationship between flow and pressure was not significantly altered (Coherence: 0.514±0.077 vs. 0.512±0.077, Gain: 0.1740±0.0756 versus 0.2341±0.0287 at 0.03 Hz). Our data demonstrate that although myogenic mechanisms may have some role in determining tonic cerebral flow, they have no clear involvement in cerebral autoregulatory blood flow control in humans.
Nitric oxide mediates arachidonic acid and prostaglandin E2‐ induced cerebral vasodilation independent of carbon monoxide
Authors: Kanu Alie Joseph , Leffler Charles W.
Published: June 2021

Nitric oxide mediates arachidonic acid and prostaglandin E2‐ induced cerebral vasodilation independent of carbon monoxide Carbon monoxide (CO) and nitric oxide (NO) are endogenously produced gaseous signaling molecules that can be involved in regulation of cerebral circulation. PGE2 has been reported to increase NO production. Moreover, NO has been shown to be required as a permissive factor for CO‐induced cerebral vasodilation. NO also stimulates CO production in cerebral microvessels. Therefore, AA and PGE2 generated in cerebral microvessels may increase cerebrovascular dilation either through NO or CO. In this study we tested this hypothesis by examining the effect of NO synthase inhibitors on the cerebrovascular response to AA and PGE2. Experiments were performed on anesthetized newborn pigs with closed cranial windows. In experiments with PGE2, indomethacin (5mg/kg i.v.) was administered to inhibit COX. Application of AA (10−7–10−5 M) or PGE2 (10−7 10−5 M) on cerebral vessels increased pial arteriolar diameter, which was blocked by both inhibitor of nitric oxide synthase, L‐NNA (1×10−6 M) and heme oxygenase (HO) inhibitor chromium mesoporphyrin (CrMP) (2×10−5 M). Sodium nitroprusside (SNP) (1×10−9–10−6 M)‐induced cerebral vasodilation was not blocked by either L‐NNA or CrMP. These data suggest that NO mediated AA‐ and PGE2‐induced cerebral vasodilation is independent of CO in newborn piglets.
Role for αvβ3 in the regulation of Ca2+ dynamics and myogenic tone development in rat cerebral arteries
Authors: Mufti Rania , Brett Suzanne E , Welsh Donald G
Published: June 2021

Intravascular pressure induces cerebral arterial tone by augmenting the activity of voltage‐gated Ca2+ channels (VGCC) and the generation of Ca2+ waves from the sarcoplasmic reticulum (SR). The signaling events that enable intravascular pressure to alter cytosolic Ca2+ dynamics and arterial tone remain uncertain. In this study we propose that the αvβ3‐integrin along with the downstream signaling proteins, focal adhesion kinase (FAK) and phospholipase C (PLCγ1), play a central role in the transduction of the myogenic response. In rat cerebral arteries denuded of endothelium, elevated intravascular pressure (20 to 80 mmHg) augmented FAK/PLCγ1 phosphorylation and the mobilization of Ca2+ from the extracellular space and the SR. These changes in cytosolic Ca2+ dynamics influenced the activity of myosin light chain kinase/phosphatase and consequently myogenic tone. Blocking αvβ3 with RGB peptides attenuated FAK/PLCγ1 phosphorylation, Ca2+ mobilization, the activation state of myosin light chain kinase/phosphatase and pressure‐induced tone. PLC inhibition with U73122 initiated a similar attenuating effect. In closing, this study highlights a key role for integrins, FAK and PLC in sensing changes in intravascular pressure, the mobilization of cytosolic Ca2+ and in the development of myogenic tone. Supported by the Natural Science and Engineering Research Council of Canada.
Smooth Muscle Cells Specific Mineralocorticoid Deletion Does Not Alter Middle Cerebral Artery Structure in Mice
Authors: Pires Paulo Wagner , McCurley Amy , Jaffe Iris Zamir , Dorrance Anne McLaren
Published: June 2021

We demonstrated that remodeling of the middle cerebral artery (MCA) in rats is in part dependent on the mineralocorticoid receptor (MR). MR mediated MCA remodeling leads to reduction in lumen diameter and increase in wall thickness. These changes can increase stroke risk and damage after cerebral ischemia. Recent studies demonstrate that MR in smooth muscle cells (SMC) directly regulates gene expression and function. We hypothesized that MR deletion in SMC play a role in MCA remodeling. SMC‐specific MR deletion (SMC‐MR−/−, n=8) in mice was achieved through expression of CRE‐recombinase driven by a SMC‐specific promoter and loxP sequences flanking exons 4 and 5 of the MR gene. MR floxed, Cre negative (WT, n=7) littermates were controls. MCAs from 9 months‐old mice were mounted on a pressure myograph to assess passive structure. Data are mean ± SEM, SMC‐MR−/− vs WT, at 80mmHg intralumenal pressure. SMC‐MR−/− did not alter MCA lumen diameter (151.6±2.8 vs 155.7±2.6μm), outer diameter (169.1±2.8 vs 171.7±2.8μm), wall thickness (8.75±0.2 vs 8.0±0.3μm) and the wall‐to‐lumen ratio (0.06±0.01 vs 0.05±0.01). MR deletion did not alter extracellular parameters in the MCA, such as stress (696±24 vs 785.8±33), stiffness (β‐coefficient: 5.58±0.4 vs 5.56±0.3), and distensibility (68.4±5.6 vs 71.5±5.2). This data suggest that under normal physiological conditions SMC‐MR does not have deleterious effects in the MCA in mice.
Cerebral autoregulation in humans: role of the cholinergic mechanisms
Authors: Tan Can Ozan , Taylor J. Andrew , Hamner Jason W.
Published: June 2021

Cholinergic mechanisms in cerebral autoregulation remain poorly characterized. However, there is some evidence for a cholinergic role. For example, cholinesterase inhibitors improve cerebral blood flow and cerebrovascular reactivity in Alzheimer patients who respond to treatment. Therefore we examined cerebral blood flow responses to augmented arterial pressure oscillations with and without cholinergic blockade. Oscillatory lower body negative pressure (OLBNP) was used at six frequencies from 0.03 to 0.08 Hz in 9 healthy subjects with and without cholinergic blockade via glycopyrrolate. Cholinergic blockade resulted in an increase in mean blood pressure and heart rate, but had no effect on cerebral flow. The transfer function relationship to arterial pressure at frequencies greater than 0.05 Hz were significantly increased (Coherence: 0.740±0.061 vs. 0.908±0.052, Gain: 0.668±0.070 vs. 0.962±0.027 at 0.08 Hz), but both the coherence and gain of the relation remained weak at the lowest frequencies in the cerebral circulation. Our data demonstrate a strong, frequency dependent role for cholinergic regulation of blood flow in the cerebrovasculature. However, the frequency dependence is similar to the sympathetic system, and thus the two mechanisms may have complimentary or redundant roles in autoregulation.
Subarachnoid hemorrhage (SAH)‐linked brain inflammation contributes to arteriolar dilating dysfunction and neuropathology in rats
Authors: Xu Hao-liang , Paisansathan Chanannait , Vetri Francesco , Pelligrino Dale
Published: June 2021

Brain injury and death arising from SAH remains a substantial clinical problem. In the present study, rats were subjected to SAH, via suture perforation of the anterior cerebral artery. In pilot experiments, we detected marked elevations in CSF expression of the astrocytic protein, S100B, at 48h post‐SAH. Since S100B is a ligand for the pro‐inflammatory receptor, RAGE (the receptor for advanced glycation end products), we tested the hypothesis that brain inflammation leads to impairment of arteriolar dilating function and contributes to brain damage. In rats prepared with closed cranial windows at 1–3 days post‐SAH, pial arteriolar dilation assessments were performed using intravital microscopy/videometry. To evaluate the role of S100B and RAGE, rats were given the following treatments at 30 min post SAH: (1) ONO 2506 (10 mg/kg, ip), a novel S100B inhibitor; or (2) sRAGE (icv via osmotic pump), a soluble RAGE decoy. After SAH, we observed diminished pial arteriolar responses to hypercapnia, and topically‐applied adenosine, acetylcholine, and S‐nitroso‐N‐acetyl penicillamine, with maximum attenuation seen at 48 h post SAH. The applications of both ONO 2506 and sRAGE significantly prevented the impaired pial arteriolar dilating responses. Neuropathology at 48h post‐SAH was evaluated using FluoroJade B (FJB) staining, which detects damaged neurons. The high level FJB reactivity seen in the ipsilateral cortex, hippocampus, and striatum in vehicle controls was markedly diminished in ONO 2506‐ and sRAGE‐treated rats. Collectively, these results indicate that, the activation of the S100B/RAGE – related proinflammatory pathway plays an important role in SAH‐associated cerebral vascular dysfunction. Blockade of the enhanced S100B and RAGE interaction may provide a promising treatment against SAH‐associated brain damage.

Support: NS63279; HL88259