bluuebunny/crossref_metadata_2025_split huggingface dataset:
Significance of Endothelial ENaC in NO Synthesis and Blood Pressure
Authors: Ydegaard Rikke , Lærkegaard Hansen Pernille B. , Svenningsen Per , Oxlund Christina Stolzenburg , Jacobsen Ib Abildgaard , Jensen Boye L 
Published: November 2023

The epithelial sodium channel, ENaC, is located in thevascular endothelial cells and inhibits eNOS and nitric oxide (NO) synthesis in single cells. Aldosterone‐MR stimulates activity of ENaC. We hypothesized: 1) Spironolactone (MR blocker) and amiloride (ENaC blocker) increase NO formation in hypertensive patients 2) ENaC‐antagonists amiloride and benzamil lead to an acute NO‐dependent blood pressure reduction in mice.Methods1) Nitrite/nitrate(surrogate for NO) was measured in urine/plasma before and after spironolactone (25–50 mg, 8 weeks (n=119)) or placebo and amiloride treatment (5–10 mg, 8 weeks n=60). 2) Indwelling catheters were implanted in the femoral artery and vein in wild type and eNOS deficient mice for undisturbed chronic blood pressure and heart rate recordings and infusion of drugs. 3 doses of amiloride (0.005–0.5 mg/kg) were administered in boli and blood pressure was recorded with high resolution for 10 minutes at each level. In wild type mice, acute effect of benzamil (0.05 mg/kg) was investigated two days after administration of amiloride.Result1) NOx/creatinineratio in urine decreased after spironolactone (P=0.01, n=58) with no difference after placebo. No differences in cGMP or NOx levels in plasma and urine were detected after treatment with amiloride 2) A significant acute and transient fall in blood pressure and heart rate was observed in mice receiving amiloride compared with vehicle (p=0.04, n=10), but not after benzamil. In order to investigate if nitric oxide was a part of the observed response, the effect of amiloride was investigated in eNOS deficient mice. Here, 0.05 and 0.5 mg/kg amiloride also significantly lowered blood pressure (n=9).ConclusionAdministration of amiloride leads to an acute and transient fall in BP and HR in mice, indicating such rapid effects that other mechanisms than renal sodium excretion could be relevant. The observed response on BP was not dependent on eNOS and likely not mediated by ENaC. Amiloride and spironolactone are not likely to have antihypertensive action through endothelial ENaC.Support or Funding InformationThe Danish Heart Foundation
Hydrogen Sulfide Decreases Blood Pressure by Influencing the Excitability of Area Postrema Neurons
Authors: Smith Pauline M , Wang Susan J , Ferguson Alastair V 
Published: November 2023

Hydrogen sulfide (H2S), an endogenous gaseous transmitter, has been shown to act in the central nervous system (CNS) to influence cardiovascular (CV) function. Microinjection of H2S into central autonomic control centers such as the paraventricular nucleus and subfornical organ has been shown to increase blood pressure (BP) and electrophysiological studies have demonstrated that H2S depolarizes neurons in these same regions. Depolarizing effects of H2S have also been demonstrated in the nucleus tractus solitarius, a medullary autonomic control center with reciprocal connections to the immediately adjacent area postrema (AP). The AP is a circumventricular organ (CVO) with well documented roles in cardiovascular regulation.The present study was undertaken to examine the cardiovascular effects of microinjection of the H2S donor, sodium hydrogen sulfide (NaHS), into the AP of urethane anesthetized male Sprague Dawley rats and the cellular consequences of bath application of NaHS on the excitability of dissociated AP neurons. Microinjection (0.5 μl) of NaHS (10 μM) caused rapid, short duration (<90 sec) decreases in BP (mean area under the curve (AUC) =−389.2 ± 82.6 mmHg*sec, n=6) and HR (mean AUC = −6.6 ± 1.4 beats, n=6) while whole cell perforated patch electrophysiology revealed that bath application of NaHS (1mM) elicited solely hyperpolarizing responses (mean Δ in membrane potential = −3.6 ± 0.8 mV, n=8) in the majority (n=8/13) of AP neurons tested. These observations identify the AP as a CNS location at which H2S may act to influence cardiovascular regulation.Support or Funding InformationSupported by Canadian Institutes of Health Research
Myeloid‐Derived Suppressor Cells in Adipose Tissue Homeostasis
Authors: Stivers Katlin Brooke , Chilton Paula , Beare Jason , Dale Jacob , Kaufman Christina L , Hoying James B 
Published: November 2023

Under steady‐state conditions, adipose tissue (AT) is highly metabolic, using free fatty acid (FFA) oxidation reactions to maintain an appropriate energy balance within the body. Even at relatively low concentrations, the by‐products of these reactions, such as reactive oxygen species (ROS), can lead to tissue damage and have been implicated as being partially responsible for inducing the chronic AT inflammation seen in obesity. This inflammation is also known to increase insulin resistance in the adipose, leading to diabetes. A network of adipose‐resident immune cells copes with this ever present threat of FFA oxidation and ROS induced inflammation with potent immunosuppressive mechanisms which help to maintain immune homeostasis within the tissue. During obesity, this homeostasis is disrupted by the infiltration of inflammatory cells into the adipose. This abject phenotypic switch of adipose‐resident immune cells has brought to light the importance of understanding how these cells work to maintain this initial homeostasis in lean adipose and what signals lead to the degradation of this immunosuppressive network during obesity.Initial flow cytometry data, from our lab's previous studies, revealed a functionally important population of CD11b+ Gr1+ stromal cells in the adipose. This surface marker combination, along with the anti‐inflammatory nature of lean adipose in general, led us to hypothesize that these cells were myeloid‐derived suppressor cells (MDSCs). MDSCs are a heterogeneous collection of immunosuppressive cells typically associated with cancer or chronic inflammatory diseases. We used flow cytometry to determine the surface marker expression profiles of the resident myeloid cells in the SVF, while CFSE and MTT assays were used to test the ability of SVF subsets to suppress proliferation of activated T cells. We found that approximately 2–3% of the adipose stroma expressed the classic CD11bhi Ly6Chi Ly6G− SSClow MDSC surface marker phenotype. Co‐culturing this population with activated T cells revealed their capacity to suppress T cell proliferation. Our findings suggest that there is a population of MDSCs resident in healthy adipose tissue. These potent immunosuppressive, endogenous adipose cells could represent a new therapeutic target for diabetes and obesity, as studies have already demonstrated that injections of culture‐derived MDSCs into obese mice increases insulin sensitivity and delays the development of metabolic syndromes.Support or Funding InformationKosair Charities
Catecholamine Metabolism via Monoamine Oxidase Disrupts Oxidative Phosphorylation Efficiency in Glutathione Peroxidase‐4 Deficient Mouse and Human Myocardium
Authors: Nelson Margaret , Anderson Ethan J 
Published: November 2023

Glutathione peroxidase‐4 (GPx4) is a selenoenzyme expressed in mitochondria and nuclear compartments which exclusively neutralizes lipid peroxides. Monoamine oxidase (MAO), an outer mitochondrial membrane‐bound enzyme responsible for catecholamine metabolism, produces a reactive catechol‐aldehyde and H2O2 upon substrate deamination. Current findings in human myocardial samples from our lab show that obese/diabetic patients exhibit greater maximal MAO activity and content, but lower GPx4 compared with nondiabetic patients, suggesting that both increased MAO and decreased GPx4 act to compound levels of reactive aldehyde species in diabetic myocardium. Our preliminary experiments using nitro blue tetrazolium staining have revealed protein modification by catechol‐aldehydes derived from norepinephrine (NE) and dopamine (DA) in whole heart lysate and isolated cardiac mitochondria from mice and humans, an effect mitigated by MAO inhibitors. We further examined the effects of catecholamine metabolism via MAO on ATP production and O2 consumption (OxPhos) in isolated cardiac mitochondria prepared from WT and GPx4‐deficient (GPx4+/−) mice, and in permeabilized myofibers prepared from human atrial myocardium. Both DA and NE significantly decreased ATP production and O2 consumption in GPx4+/− mice, but not WT, by 15% and 13%, respectively (p<0.05). Furthermore, the ATP/O ratio, an indicator of OxPhos efficiency, was also reduced in the GPx4+/− mice. In human atrial myocardium (n=11), NE significantly decreased ATP/O by ~35% (p<0.05), which was attenuated by MAO inhibitors. This translational study provides evidence that 1) catechol‐aldehydes are a unique form of oxidative post‐translational modification in the heart, and 2) hearts with diminished lipid peroxide‐scavenging capacity (e.g., obese/diabetic patients) are more susceptible to catecholamine‐induced disruption of mitochondrial OxPhos via MAO.Support or Funding InformationR01HL122863
Xanthine oxidase inhibition attenuates arterial stiffness and prevents macrophage recruitment and M1 polarization in western diet fed male mice
Authors: Aroor Annayya , Jia Guanghong , Habibi Javad , Sun Zhe , Barron Brady J , Dongqing Chen , Martinez‐Lemus Luis A , Manrique Camila , Nistala Ravi , Whaley‐Connell Adam T , Meininger Gerald A , Sowers James R 
Published: November 2023

Vascular stiffness associated with obesity is emerging as an independent risk factor for cardiovascular disease but the mechanisms and mediators of obesity associated vascular stiffness are not clearly understood. In this regard, hyperuricemia caused by enhanced xanthine oxidase activity is receiving more attention as an independent risk factor for cardiovascular disease under the setting of obesity caused by consumption of a western diet (WD) rich in fat and refined sugars. We hypothesized that both xanthine oxidase and uric acid are associated with vascular stiffness and that inhibition of xanthine oxidase activity would prevent arterial stiffness in a clinically relevant model of WD‐induced obesity and cardiovascular dysfunction. Four week‐old C57BL6/J male mice were fed a WD with excess fat (46%) and fructose (17.5%) with or without xanthine oxidase inhibitor, allopurinol (125mg/L), a potent xanthine oxidase inhibitor, for 16 weeks. Xanthine oxidase inhibition had no effect on increases in body weight, and fat mass but significantly (P<0.05) improved systemic insulin resistance. Xanthine significantly attenuated WD‐induced increase in plasma uric acid levels and xanthine oxidase activity in aorta. Endothelial stiffness and extracellular matrix/vascular smooth muscle stiffness as determined by atomic force microscopy were significantly increased (P<0.05) in WD fed mice and were significantly decreased by xanthine oxidase inhibition. WD induced increases in MCP‐1, CD11b, CD86, IL‐6 and oxidative stress, were prevented by xanthine oxidase inhibition. These results suggest xanthine oxidase inhibition suppresses macrophage recruitment and M1 polarization in WD fed mice. Taken together, these findings support the notion that increased xanthine oxidase activity in the vasculature and increased production of uric acid with intake of a WD promotes vascular stiffness, vascular inflammation and maladaptive immune response that lead to vascular injury.Support or Funding InformationK08HL129074‐01 (to C.M.), VA I01 BX001981/BX/BLRD, R01‐HL073101 and R01‐HL107910 (to J.R.S).
Does Type 2 Diabetes Modulate Peripheral Cutaneous Vascular Function?
Authors: Akbari Pegah , Fujii Naoto , Boulay Pierre , Sigal Ronald J. , Kenny Glen P. 
Published: November 2023

Aging is associated with impairments in cutaneous vasodilation during heat stress (Holowatz et al. Am J Physiol, 284:1662, 2003) which is exacerbated in individuals with type 2 diabetes mellitus (Charkoudian. Mayo Clin Proc, 78:603, 2003). This diabetes‐related modulation of cutaneous vasodilation may be due to attenuated peripheral sensitivity of skin vessels to receptor activation, though this has never been directly investigated. Thus, in this preliminary study, we aimed to evaluate the influence of type 2 diabetes mellitus on the modulation of cutaneous vasodilation in response to activation of the following receptors: cholinergic, purinergic, nicotinic and β‐adrenergic. In this preliminary study, seven older adults (59±9 years) with well‐controlled T2D (hemoglobin A1c, 7.5% ± 1.0, duration 8±5 years) and seven age‐matched counterparts without T2D (Controls) (61±8 years) participated in the study. Subjects were placed in a semi‐recumbent position in a thermoneutral room (~23 °C) during which time four intradermal microdialysis fibers were implanted on the dorsal side of the left forearm within the dermal layer of the skin. Approximately 90 min after the completion of the fiber insertion, cutaneous vascular conductance (CVC, measured as laser‐doppler flowmetry/mean arterial pressure) was then continuously monitored at the four forearm skin sites perfused via intradermal microdialysis with the following receptor agonists in a dose dependent manner: 1) methacholine (cholinergic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mM), 2) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mM), 3) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mM), and 4) isoproterenol (β‐adrenergic receptor agonist, 3 doses: 1, 10, 100 μM). Increased CVC in response to all doses of methacholine administration were similar between groups (all P ≥ 0.15). Further, observed increases in CVC resulting from the five dose dependent infusion of ATP were similar in both Controls and T2D (all P ≥ 0.51), as was the case in all five doses of nicotine infusion (all P ≥ 0.32). Finally, similar increases in CVC were observed in both groups following the infusion of all three doses of isoproterenol (all P ≥ 0.20). Our preliminary findings show no attenuations in the sensitivity of the examined cholinergic and non‐cholinergic receptors in older adults with well‐controlled type 2 diabetes.Support or Funding InformationFunding support provided by the Canadian Institutes of Health Research (grant no. 286363, funds held by Dr. Glen P. Kenny).
The Role of GPR40 (FFAR1) in Pharmacological vs Physiological Control of Incretin Secretion
Authors: Chen Yanyun , Song Min , Riley Jonathan , Reynolds Nichole , Hamdouchi Chafiq , Miller Anne 
Published: November 2023

G protein‐coupled receptor 40 (GPR40), also known as free fatty acid receptor 1 (FFAR1), is a member of a family of lipid‐activated receptors that is highly expressed in the pancreas and enteroendocrine cells with lower levels expressed in the brain. GPR40 mediates medium and long chain fatty acid stimulated insulin secretion in the presence of elevated glucose levels. This glucose‐dependent insulin secretion property has established GPR40 agonists as attractive therapeutic agents for the treatment of type 2 diabetes.We have shown previously that synthetic, small molecule GPR40 agonists normalize glucose levels during oral glucose tolerance tests performed in mice after acute oral administration. In addition, incretin levels, total and active GLP‐1 and GIP, are significantly elevated immediately following oral administration of the GPR40 agonists. These findings suggest that GPR40 may play an important role in the incretin secretion following a meal. The following studies were performed to address this hypothesis.A synthetic GPR40 agonist, liquid mixed meal, or vehicle alone was administered orally at t = 0 minutes to wild type (WT) or GPR40 knockout (KO) mice and blood was collected for incretin determination at 0.5, 1.5 and 3 hours. Administration of the GPR40 agonist in WT mice led to a robust increase in active GLP‐1 with peak concentrations reaching 12 pg/ml at the 0.5 hour time point followed by levels falling to 5 pg/ml for the remainder of the study (3 hours). The changes in active GIP levels were similar. In contrast, elevations in GLP‐1 and GIP levels were absent in GPR40 KO mice demonstrating that the incretin effect following administration of the GPR40 agonist was GPR40 mediated.The same experimental design was performed in mice orally administrated a liquid mixed meal. Active GLP‐1 levels peaked at the 1 hour time point (5.5 pg/ml) and fell to levels equivalent to those seen with the vehicle control at 6 hours. Changes in active GIP levels were mild demonstrating a peak concentration at 0.5 hour (0.75 pg/ml) and rapidly returning to normal levels. Interestingly, the same changes in active GLP‐1 and GIP were seen in the GPR40 KO mice compared to those in the WT mice. These findings demonstrate that the incretin secretion following a liquid mixed meal does not require GPR40, suggesting that other receptors are responsible for the meal‐stimulated elevation in active GLP‐1 and GIP.
Physiologic Mechanisms of Insulin Resistance During a Critical Postnatal Window of Development
Authors: Ortiz Rosa Isela , Chávez‐Maldonado Juan Pablo , Velasco Myrian , Larqué Carlos Alfonso , Hiriart Marcia 
Published: November 2023

IntroductionInsulin resistance is a condition in which the insulin‐sensitive tissues cannot respond appropriately to hormone effects. Insulin resistance has been associated with pathologies however, insulin resistance is present in physiologic states such as pregnancy and adolescence. Our work group analyzed changes on glucose and insulin levels during postnatal development. We found that males and females rats near the end of lactation show insulin resistance, characterized by hyperglycemia and hyperinsulinemia, which disappears later. This state associates with a critical window in pancreatic development.ObjectiveTo determine the mechanisms involved in the insulin resistance observed in the weaning period in males and females rats.MethodsWe used male and female Wistar rats at 20 postnatal days (20 pd) and healthy adult rats (250–280 g). We analyzed fasting glucose and insulin levels and made glucose tolerance test (GTT) and insulin sensitivity test (ITT). We performed insulin‐stimulated glucose uptake assays in adipose tissue and analyzed P70S6K‐specific inhibitory sites of serine and threonine phosphorylation of IRS‐1 in adipose tissue and skeletal muscle.ResultsWe observed increased fasting glucose concentrations and insulin levels in both female and male at 20 pd, compared to adult rats. The blood glucose levels in GTT in male and female rats of 20 pd were higher to those of adults, along with the test. Systemic insulin response was less in male and female at 20 pd rats, compared to adults. Insulin‐stimulated glucose uptake in adipose tissue was lower in 20 pd, compared to adults. P70S6K phosphorylation in Thr389 and IRS‐1 phosphorylation in Ser1101 were higher in adipose tissue at 20 pd in males and females rats than in adult rats.ConclusionWistar males and females rats at 20 pd have high plasma levels of glucose and insulin compared with adult rats. These data together with the lack of response in the ITT, a higher phosphorylation of P70S6K kinase and IRS1 at a inhibitory sites and lower insulin‐stimulated glucose uptake could be involved in the development of physiological insulin resistance.Support or Funding InformationThis work was partially financed by CONACYT CB‐253222 and DGAPA IN213114
SIRT3 Inactivation Impairs Endothelial Function and Promotes Vascular Calcification in Hypercholesterolemic Mice
Authors: Roos Carolyn M , Zhang Bin M , Fujimoto Hirokazu , Hagler Michael A , Miller Jordan D 
Published: November 2023

Recent work by other investigators have shown that SIRT3 is an important regulator of endothelial function in obese patients or animals, as reductions in SIRT3 drive increased mitochondrial ROS (mtROS) production. The role of SIRT3 in atherosclerotic mice, however, remains unclear. Therefore, we hypothesized genetic inactivation of SIRT3 in hypercholesterolemic mice will impair vascular function, reduce antioxidant gene expression, and increase pro‐osteogenic signaling. We used Ldlr−⁄−/ApoB100/100 mice that were either wild‐type (LA‐SIRT3+/+) or null for SIRT3 (LA‐SIRT3−⁄−). After 12 weeks of western diet feeding, we assessed endothelial function of aorta using isolated organ bath chambers and measured changes in gene expression using qRT‐PCR. Consistent with our hypothesis, loss of SIRT3 significantly impaired relaxation to acetylcholine (Ach) (LA‐SIRT3−⁄−: 48.2%±3.0, LA‐SIRT3+/+: 57.6%±1.7). Incubation with Mito‐Tempol significantly improved endothelial‐dependent relaxation in LA‐SIRT3−⁄− mice (57.0%±2.9), but not in LA‐SIRT3+/+ mice. Interestingly, losses of SIRT3 did not alter expression of MnSOD, ecSOD, or CuZnSOD. Gene expression of the late‐stage osteoblast marker, osterix, tended to be increased in LA‐SIRT3−⁄− mice compared to wild‐type mice (p = 0.06). Collectively, losses of SIRT3 impair endothelial function and tend to increase osteogenic signaling in severe hypercholesterolemia. Importantly, these functional and molecular changes and may result from increased mtROS, which may serve as a viable therapeutic target to slow pathological processes during progression of atherosclerosis.Support or Funding InformationNHLBI R01‐HL111121
Loss of endothelial Fto is protective against metabolic disease
Authors: Krüger Nenja , Biwer Lauren A , Good Miranda E , Rüther Ulrich , Isakson Brant E 
Published: November 2023

Genetic variations within the fat mass and obesity associated gene (FTO) are known to correlate with obesity and hypertension in humans, demonstrating a possible key role in vascular health. Therefore, we hypothesized that FTO may be important at the vascular level. Because endothelial cells (EC) are known to have a central role in the development of obesity‐induced metabolic changes and hypertension, we wanted to investigate if murine loss of endothelial Fto may influence obesity‐induced pathophysiological changes. Therefore, EC‐specific Fto deficient mice were generated using a tamoxifen‐inducible Cre system. To analyze obesity‐dependent effects, mice were either fed a normal chow (NC) or a high fat diet (HFD) for 12 weeks. Regardless of the endothelial deletion of Fto, the mice still gained a significant amount of weight and were obese, indicating the Fto gene in endothelium did not inhibit weight gain like global Fto deficiency in mice. Next we determined whether loss of endothelial Fto affected obesity‐induced metabolic changes in HFD‐fed mice. While serum lipid analysis showed no differences in dependence of endothelial Fto, glucose and insulin tolerance was significantly improved in HFD‐fed mice without endothelial Fto. Due to the importance of EC in vascular tone of resistance arteries, we isolated 3rd order mesenteric arteries from NC‐ and HFD‐fed mice with and without endothelial Fto and performed pressure curves to analyze myogenic tone. While loss of endothelial Fto did not influence myogenic tone in resistance arteries of NC‐fed mice, remarkably, endothelial Fto deletion provided protection from HFD‐induced changes on myogenic tone. Subsequently, blood pressure was measured in HFD‐fed mice with and without endothelial Fto using radiotelemetry and it revealed that loss of endothelial Fto significantly reduced blood pressure. Collectively, these data suggest that loss of endothelial Fto was protective against HFD‐induced changes on myogenic tone in mesenteric arteries and subsequently reduced blood pressure in vivo without influencing body weight. Furthermore, glucose homeostasis, but not serum lipid levels, were specifically improved in HFD‐fed mice suggesting that endothelial Fto is not only important in the development of obesity‐induced hypertension, but also in the development of insulin resistance and hyperglycemia.Support or Funding InformationAHA, NHLBI and IRTG1902