bluuebunny/crossref_metadata_2025 huggingface dataset:
Renal Denervation Prevents Progression of Hypertension by Reversing Baroreflex Resetting in a Rabbit Model of Chronic Kidney Disease
Authors: Sata Yusuke , Burke Sandra L , Lim Kyungjoon , Esler Murray D , Schlaich Markus P , Head Geoffrey A
Published: November 2023

Background

Hypertension progresses rapidly when associated with chronic kidney disease (CKD) to become treatment‐resistant. Renal denervation (RDN) is reportedly effective in lowering blood pressure in this disease but the pathophysiological mechanisms are not fully investigated. A rabbit model of moderate CKD, induced by 11/12th nephrectomy and characterised by rapid and sustained elevation of plasma creatinine and blood pressure allows for determination of the effects of RDN and whether its efficacy improves with time.

Aims

To determine the short‐ and long‐term effects of RDN on CKD‐induced changes to mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA), baroreflex function and renal function.

Methods

CKD was induced by lesioning of the left kidney and right nephrectomy. In 2 weeks, rabbits underwent bilateral RDN or sham‐RDN. RSNA, recorded from the left renal nerve, and MAP were measured weekly, and baroreflexes were examined 2 and 4 weeks after RDN or sham‐RDN.

Results

Two weeks after induction of CKD, creatinine increased by 59% and remained elevated by 41% over the following 4 weeks. MAP had increased by 14% to 77±1 mmHg after CKD and continued to rise from this level by +8% and +13% after 2 and 4 weeks in sham‐RDN rabbits. However, in rabbits which underwent RDN, there was no further increase in MAP over the 4 weeks. RSNA was 23% lower 2–3 weeks following RDN than after sham‐RDN (P<0.05). CKD shifted the RSNA baroreflex towards the higher MAP and this was reversed after 2 weeks of RDN with marked reductions in gain (38%) and range (42%). There was no further change to the baroreflex after 4 weeks RDN (Fig). Neither GFR (14±2 ml/min in controls), which was 45% lower in CKD rabbits, nor creatinine levels were altered by 4 weeks of RDN.

Conclusion

RDN is effective for 4 weeks in ameliorating the hypertension in this model of CKD. Sympathetic activation and the baroreflex resetting were also reversed without altering renal function. These are the pathophysiological rationale to target renal nerves in the treatment of hypertension with moderate CKD.
Effects of Hydrogen Sulfide on Mesenteric Blood Flow
Authors: Barrera Adelaeda , Naik Jay , Gonzalez Bosc Laura V. , Mendiola Perenkita , Kanagy Nancy L.
Published: November 2023

In sleep apnea, recurrent obstruction of the upper airway leads to sleep fragmentation and intermittent hypoxia (IH). In animal studies, IH causes wake‐time hypertension by elevating vascular resistance due in part to decreased production of the vasodilator, hydrogen sulfide (H2S). Inhibiting cystathionine γ‐lyase (CSE) to prevent H2S synthesis augments constriction in isolated mesenteric arteries, but H2S regulation of resistance in this vascular bed in vivo is unknown. The goal of this study was to evaluate CSE regulation of blood flow and resistance in the mesenteric circulation of control rats and in rats made hypertensive by exposure to IH for 14 days. We hypothesized that inhibiting CSE would increase vascular resistance and mean arterial pressure (MAP) more in control than in IH exposed rats. Rats were anesthetized with inhaled isofluorane (2%) and instrumented with femoral artery and vein catheters as well as Doppler flow probes on the main mesenteric artery. Under anesthesia, CSE inhibition (β‐cyanoalanine, BCA, 30mg/kg bolus + 5 mg/kg/min for 20 minute) increased MAP in both control and IH rats compared to saline infusion (control: 7.2±1.2 vs. −2.8±1.1; IH: 9.3±1.1 vs. 3.3±0.7, % change from baseline, p<0.05, n=6–8 rats per group) but did not alter mesenteric resistance. To determine if anesthesia masked acute changes in vascular resistance in response to CSE inhibition, the study was repeated in conscious animals. In conscious control rats, BCA infusion significantly increased MAP (saline −0.8±1.18 vs BCA 7.9±2.55, % change from baseline, p<0.05, n=7) and mesenteric resistance (saline 0.9±3.1 vs BCA 15.6±6.5, % change from baseline, p<0.05, n=12). We then tested our hypothesis that chronic CSE inhibition would increase vascular resistance and MAP in control but not in IH rats. The irreversible CSE inhibitor DL‐propargylglycine (PAG) was used to permit a once daily i.v injection (50 mg/kg/day for 5 days). CSE inhibition significantly increased both, MAP and mesenteric resistance in control but not in IH rats (MAP: control: 110.3±2.9 vs. 122.4±4.0 post PAG; IH: 118.8±2.1 vs. 111.3±3.7 post PAG, mmHg, p<0.05 n=3–5 rats per group; Relative mesenteric resistance normalized to starting values: Sham: 1±0 vs. 1.5±0.07.1; IH: 1±0 vs. 0.85±0.19, p<0.05, n=3–5 rats per group). Our results suggest that endogenous H2S is an important regulator of blood pressure and mesenteric vascular resistance and that this control is lost after IH exposure.

Support or Funding Information

This work was supported by the NIH, NHLBI, and AHA [Grants HL123301, HL007736‐21, and 15GRNT25090039 (LGB)] and institutional funding from the University of New Mexico.
Blood Pressure Response to Isometric Exercise During Short‐term Water Restriction
Authors: Watso Joseph , Babcock Matthew C , Stocker Sean D , Wenner Megan M , Farquhar William B
Published: November 2023

Water restriction causes an acute decline in plasma volume and elevation in plasma osmolality, both of which can increase sympathetic outflow. Greater sympathetic outflow is associated with alterations in blood pressure (BP) variability and BP reactivity.

PURPOSE

To test the hypothesis that water restriction increases BP variability and BP reactivity.

METHODS

Eleven healthy participants (5M/6W, age: 24±1 yrs; BMI: 24.3±1.0 kg/m2; BP 110±4/64±2 mmHg) completed two hydration protocols in a randomized order, separated by a month. Daily water intake for the euhydration (EU) condition was 23 mL H2O/kg/day for 3 days prior to testing on day 4. Water intake for the hypohydration (HYPO) condition included a stepwise reduction in water intake for 3 days, followed by a 16‐hour water restriction period prior to testing. Participants wore an ambulatory BP monitor and collected urine for 24 hours preceding each study visit. Subjects completed a 2‐minute bout of isometric handgrip exercise at 40% of their maximal voluntary contraction (HG) followed by 3 minutes of post‐exercise ischemia (PEI). Beat‐by‐beat BP was measured continuously with finger photoplethysmography.

RESULTS

Plasma volume declined 4.9±0.7% during the HYPO condition and plasma osmolality was significantly elevated in the HYPO compared to the EU condition (288.0±1.2 vs. 284.6±1.3 mOsm/kg H2O, p<0.05). Several other variables suggested mild dehydration during the HYPO condition, including higher urine osmolality (634±48 vs. 432±52 mOsm/kg H2O, p<0.05), urine specific gravity (1.018±0.002 vs. 1.011±0.001, p<0.05) and thirst rating on a 0–10 scale (6.1±0.2 vs. 1.9±1.0, p<0.05). Despite this, preliminary data suggest no change in beat‐by‐beat BP variability (SD mean BP 1.3±0.0 vs. 1.4±0.1, p>0.05) or ambulatory BP variability (SD mean BP 11.7±0.4 vs. 11.4±1.2, p>0.05) during the HYPO compared to the EU condition. BP reactivity during HG (Delta mean BP 10±3 vs. 13±2 mmHg, p>0.05) or PEI (Delta mean BP 13±3 vs. 13±2 mmHg, p>0.05) was not different between conditions. Heart rate change from baseline to HG and PEI was also not different between conditions (p>0.05).

CONCLUSION

These preliminary findings suggest that short‐term water restriction in young healthy adults does not increase BP variability or BP reactivity.

Support or Funding Information

Supported by NIH Grant 1R01HL128388‐01A1
Ablation of MMP9 upregulates autophagic flux in the diabetic heart
Authors: Nandi Shyam Sundar , Mishra Paras Kumar
Published: November 2023

Autophagy is a lysosome‐mediated catabolic process for recycling of defective cytoplasmic components. Matrix metalloproteinase‐9 (MMP9) is a collagenase, and ablation of MMP9 is cardioprotective for diabetic hearts. However, whether the cardioprotective role of MMP9 ablation is mediated by autophagic adaptation is unclear. We hypothesized that ablation of MMP9 protects the diabetic heart by upregulating cardiac autophagic flux. To test the hypothesis, we used 12–14 week male WT (C57 BL/6J), Ins2+⁄− Akita (Type1 diabetic), MMP9 knockout (MMP9−⁄−), and Ins2+⁄−/MMP9−⁄− (DKO) mice. DKO mice were generated by cross‐breeding male Ins2+⁄− Akita with female MMP9−⁄− mice. We measured the levels of LC3B‐II protein accumulation (autophagic flux marker) in these mice using bafilomycin A1 (inhibitor of autophagic degradation). To evaluate the cardiac function, we performed M‐mode echocardiography. For in vitro studies, we generated stable MMP9−⁄− HL1 cardiomyocyte cell line using CRISPR‐cas9 technique (MMP9−⁄− HL1). Autophagic flux was measured in control and MMP9−⁄− HL1 cardiomyocytes treated with low (LG‐5mM) or high (HG‐25mM) dose of D‐glucose. Our results revealed that autophagic flux is upregulated in MMP9−⁄− hearts (1.44±0.07 fold) as compared to WT hearts. Autophagic flux was also upregulated in Ins2+⁄− Akita hearts (1.3±0.12 fold) as compared to WT hearts. However, ablation of MMP9 in Ins2+⁄− Akita further increases cardiac autophagic flux (1.75±0.25 fold of Akita). The in vitro studies demonstrated that ablation of MMP9 in HL1 cardiomyocytes upregulates autophagic flux (2.6±1.4 fold) as compared to control HL1 cardiomyocytes. Moreover, HG treatment increased autophagic flux (1.4±0.25 fold) in HL1 cardiomyocytes, which was further increased by MMP9 ablation (1.7±0.24 fold) in HL1 cardiomyocytes. M‐mode echocardiography showed that percentage ejection fraction (% EF) was decreased in diabetic Akita as compared to WT (WT: 61.41±2.84 and Akita: 48.40±2.44) mice, but it was restored in DKO (61.28±0.71). There was no significant change in % EF in MMP9−⁄− (61.89±1.46) mice. These findings demonstrate a novel MMP9‐mediated regulation of autophagy in the diabetic heart, where ablation of MMP9 induces cardiac autophagic flux in the diabetic heart that may contribute to ameliorate cardiac dysfunction.

Support or Funding Information

American Heart Association Postdoctoral fellowship award 16POST30180003 and NationalInstitute of Health grants HL113281and HL16205
Sympathetic decentralization after spinal cord injury spares Zucker Diabetic Fatty rats from frank diabetes
Authors: Poormasjedi‐Meibod Malihe‐Sadat
Published: November 2023

Introduction

Metabolic syndrome, characterized by the constellation of visceral obesity, atherogenic dyslipidemia, proinflammatory state, hypertension, and insulin resistance, confers a 5‐fold increase in the risk of type 2 diabetes (T2D). Accumulating data from human and animal studies revealed a strong association between sympathetic nervous system (SNS) activation and different components of metabolic syndrome, such as obesity, hypertension, and insulin resistance. However, it is not clear whether sympathoexcitation is a cause or result of metabolic syndrome and the subsequent T2D. Here we used high thoracic spinal cord injury (SCI) as an effective means for SNS decentralization in order to investigate the potential role of the SNS in the pathogenesis of T2D in an animal model of metabolic syndrome.

Method/Design

Eighteen male Zucker Diabetic Fatty rats (ZDF‐Leprfa/fa, Metabolic syndrome/T2D animal model) were evenly assigned to two groups: uninjured (Fatty‐Sham), and T3 complete SCI (Fatty‐SCI). Lean Zucker Diabetic Fatty rats (ZDF‐Lepr+, n = 9) acted as controls. T2D development was evaluated using biweekly random blood glucose measurements and oral glucose tolerance test (OGTT) at week 11 post‐injury. Twelve weeks post‐injury, animals were euthanized and blood samples and pancreas tissue were collected for further analyses.

Results

We found that SCI‐induced SNS decentralization, manifested by a dramatic decline in plasma norepinephrine (P = 0.011), was accompanied by improved glucose tolerance, i.e. decreased glucose area under the curve (AUC, P = 0.001), increased fasting insulin (1.00 ± 0.33 vs. 3.02 ± 1.5 ng/ml, p = 0.011), and augmented insulin response after an OGTT, i.e. increased insulin AUC (P = 0.001) in the Fatty‐SCI group compared to uninjured Fatty‐Sham group. Although Fatty‐Sham and Fatty‐SCI groups exhibited a comparable degree of insulin resistance, Fatty‐SCI had significantly higher β‐cell activity indicated by a significant increase in homeostatic model assessment‐%B (HOMA‐%B) index (P = 0.0064). Pancreatic gene expression analysis revealed that SCI caused a significant reduction in the local expression of inflammatory mediators, i.e. IL‐1β and TNF‐α, which are critical for inhibition of insulin secretion, and induction of β‐cell apoptosis and dysfunction. While SNS decentralization spared the Fatty‐SCI rats from frank diabetes, Fatty‐SCI and Fatty‐Sham rats both exhibited other components of metabolic syndrome, including abdominal obesity and dyslipidemia, as compared to lean rats.

Support or Funding Information

This work has been supported by Michael Smith Foundation for Health Research, Craig H. Neilsen Foundation, Heart and Stroke Foundation of Canada, and the International Collaboration on Repair Discoveries.
Chronic E‐Cigarette Usage on Blood Glucose
Authors: Hoskinson Hannah Nicole , Breit Matthew , Pitzer Christopher , Wu Zhong X , Olfert I M , Bryner Randy
Published: November 2023

Introduction

Traditional cigarette usage has been linked to a number of nefarious metabolic effects, including insulin resistance, however the effects of electronic cigarettes (E‐cigs) are not currently known. Advertised as a safe alternative for traditional tobacco cigarettes, long‐term studies investigating the metabolic effects of E‐cigs are lacking. The purpose of this study was to gain a better understanding of the possible metabolic consequences of E‐cig usage. We hypothesize E‐cig usage will induce insulin resistance in mice.

Methods

C57BL/6 mice were divided between E‐cig (n=13) and control (n=13) groups and exposed to either vaporized cappuccino flavored E‐cig liquid (18 mg/mL nicotine) or filtered air for 4h/d, 5 d/wk for 6 months. Fasting blood glucose (FBG) and glucose tolerance (GTT) were assessed following an overnight fast. A glucose bolus was administered via gelatin pellet (3g glucose/kg) which was ingested within 2 min. Blood was collected by tail nick and glucose measured using Bayer Contour glucometer and test strips.

Results

After 6 months exposure, total body mass (28.1 ±3.2g vs 27.3 ±3.1g) and lean body mass (18.71 ±0.25g vs 18.38 ±0.27g) were similar between E‐cig and air exposed groups, respectively. Likewise, E‐cig exposure did not result in significant difference in FBG (128. ±35mg/dL vs 120 ±33mg/dL), GTT0‐120, and peak glucose response (174 ±6mg/dL vs 159 ±6mg/dL, p=0.08). However for GTT0‐30 there was a significant interaction for glucose response between the groups (p=0.05).

Conclusion

These results suggest there may be some initial differences in glucose response in animals exposed to E‐cigs when compared to controls, however FBG and overall glucose handling was not significantly different between the groups. Future studies are needed to determine if greater levels of nicotine exposure via E‐cigs contribute to impairment of glucose metabolism.

Support or Funding Information

NIH Grant P20GM103434 (West Virginia IDeA Network for Biomedical Research Excellence) and Marshall‐WVU Health Initiative Award
Lhx1 is Required for Beta Cell Function Via Regulation of Glp1 Receptor (Glp1R)
Authors: Bethea Maigen M , Liu Yanping , Wade Alexa K , Habegger Kirk M , Hunter Chad S
Published: November 2023

Diabetes mellitus is a disease by which functional insulin producing beta cells are lost. Understanding the transcription factor and co‐regulator complexes that govern beta cell development and function is essential for the generation of novel therapeutics and or cell replacement strategies to treat this disease. Our lab previously showed that the LIM‐homeodomain (LIM‐HD) transcription factor Islet‐1 (Isl1) interacts with the LIM domain binding protein 1 co‐regulator (Ldb1) to regulate key beta cell genes (e.g. Glp1R and MafA). However, recent mRNA analysis and immunofluorescence studies revealed the presence of another LIM‐HD transcription factor in the pancreas, LIM homeobox 1 (Lhx1). Through co‐immunoprecipitation experiments in beta cell nuclear extracts, we found that Lhx1 also interacts with Ldb1 and surprisingly, Isl1. This suggests that a novel Lhx1‐Ldb1‐Isl1 complex exists in beta cells. We therefore hypothesized that Lhx1 regulates similar target genes as Ldb1 and Isl1. To test this, we employed siRNA‐mediated Lhx1 knockdown along with chromatin immunoprecipitation experiments. We discovered that, Lhx1 knockdown in beta cell lines resulted in significantly reduced Glp1R transcripts. Additionally, we revealed that Lhx1 occupied a regulatory domain of Glp1R. Together, these data suggest that Lhx1 directly regulates Glp1R. Glucagon‐like peptide‐1 (Glp1) is an incretin hormone secreted from the L‐cells in the gut that acts through a receptor (Glp1R) on pancreatic beta cells to increase the production and secretion of insulin. To uncover pancreatic Lhx1 roles in vivo, we generated a mouse model of pancreas‐wide Lhx1 deficiency. Mutant mice were born in expected ratios and appeared overtly normal. However, Lhx1 loss led to hyperglycemia in aged mice, plus significantly reduced Glp1R transcripts in isolated islets. Therefore, we assessed beta cell responses to Glp1 in mutant mice by employing a Glp1R agonist during an intraperitoneal glucose tolerance test. Mutant mice treated with agonist displayed a dampened ability to clear blood glucose when compared to agonist treated controls. This suggested that Lhx1‐deficient mice lack an ability to respond to Glp1. Taken together, our data reveal for the first time that Lhx1 directly regulates the beta cell Glp1R gene. Future studies will examine the role of Lhx1 in pancreas following physiological stressors (e.g. high fat diet).

Support or Funding Information

We thank our funding sources: NIH‐NIDDK DK094842 and DK105209; ADA 1‐16‐JDF‐044, UAB Endocrinology Startup, and the UAB Comprehensive Diabetes Center
Attempting to improve the health of rural Kentucky citizens through educating its youth with health integrated school work and online mentoring interactions
Authors: Cooper Richard Morris , Byrd LaShay , Ho Jenni , Wilson Jennifer , Krall Rebecca McNall , Capilouto Gilson J. , Cooper Robin L
Published: November 2023

Kentucky consistently ranks among the top ten states nation‐wide for the highest rates of chronic, preventable diseases. High school graduates in Kentucky are only required to successfully complete one semester of health, of which the course‐work is didactic and rarely transformative. The adoption of the Next Generation Science Standards, which advocate deep understanding and application of content, and using science to make informed decisions, provides a natural opportunity to integrate the National Health Education Standards into required science classes. We are developing an educational unit around the topic of Metabolic Syndrome (MSy). We capitalize on the knowledge of the life cycle, physiology, genetics, and behavior of Drosophila melanogaster to investigate the effects of diet on development, survival, behavior, environmental stress on survival and behavior, as well as physiological functions such as heart rate and neural‐muscular function with sensory motor tasks. We have started with high school classes defining the disease of MSy and contributing factors. High school classes are now designing live models of fruit flies fed different diets and examining the health (behavior, heart function, development and survival) of the fly populations. Students are developing talking points based on what they have personally learned, design displays, and use their models to teach others. For a culminating event, students will set up their demonstrations and displays, much like they do for a school science fair/symposium, in the places where rural people congregate the most ‐ parent teacher conference night, churches, ball games, flea markets.

Support or Funding Information

College of Health Sciences, Univ. of KY. & personal funds (RLC).
The differential roles of Ca2+/Calmodulin‐dependent protein kinase IIδ2 and δ6 (CaMKIIδ2 and δ6) in mediating remodeling of human venous smooth muscle
Authors: Ginnan Roman Gregory , Shah Ravi , Lui Yong Feng , Conti David , Singer Harold A
Published: November 2023

Arteriovenous fistulas (AVF) provide vascular access for lifesaving hemodialysis and involve the surgical bridging of the radial artery to the cephalic vein. The creation of the AVF results in the remodeling of the cephalic vein due to its exposure to arterial flow. Previous studies have demonstrated a positive role for CaMKIIδ2 in VSM cell proliferation and migration promoting arterial remodeling but little is known regarding CaMKII's role in mediating venous remodeling. Immunoblotting reveals an increase in the expression of CaMKII in remodeled human arteriovenous fistulas (AVF) as compared to controls. QPCR analysis indicates an increase in the CaMKIIδ isoform in these remodeled AVFs. Using CaMKIIδ selective antibodies we show an increase in CaMKIIδ2 and CaMKIIδ6 expression in the remodeled AVFs although PCR studies indicate that message for both CaMKIIδ isoforms is present in controls also. Immunofluorescent and biochemical analyses indicate that CaMKIIδ2 is expressed in the medial wall of control veins but is diminished in the medial wall of remodeled AVFs. Interestingly, CaMKIIδ2 expression is enriched in the neointimal lesions of remodeled AVFs. Conversely, CaMKIIδ6 is expressed in the medial wall of control veins and remodeled AVFs but not in the neointimal lesions of the remodeled AVFs. Studies in cultured VSM cells and an animal model of occlusive vascular disease indicate that overexpression of CaMKIIδ6 attenuates VSM cell migration and restenotic lesion development. Together, these studies indicate differential roles for CaMKIIδ isoforms in human vascular disease. While CaMKIIδ2's presence in the neointimal lesion and its known proliferative and promigratory functions indicate a positive role in neointimal lesion development, CaMKIIδ6's presence in the medial wall and its antimigratory function indicate a vasculoprotective role that could potentially be harnessed to ameliorate vascular disease.

Support or Funding Information

RO1HL49426‐21 (H.S)

DCI Paul Teschan Research Fund (H.S)
Chronic Cerebral Hypoperfusion Impairs Transient Receptor Potential Channel Vanilloid 4 (TRPV4)‐Mediated Dilation in Cerebral Parenchymal Arterioles From Normotensive, but not Hypertensive Rats
Authors: Dorrance Anne McLaren , Matin Nusrat , Fisher Courtney , Jackson William F
Published: November 2023

Hypertension is a risk factor for cerebral small vessel disease and vascular cognitive impairment. Hypertension also increases the risk of other vascular injuries, such as carotid artery stenosis, that can place additional stress on the cerebral vasculature. To understand how hypertension affects the vascular response to reduced cerebral perfusion we studied normotensive Wistar Kyoto (WKY) rats and stroke prone spontaneously hypertensive rats (SHSRP). Rats underwent a bilateral carotid artery stenosis (BCAS) surgery or a sham surgery at 20 weeks of age, and they were studied 8 weeks later. In both cases the BCAS surgery impaired short‐term memory assessed by calculating the novel object exploration quotient (WKY: 0.6±0.04 vs 0.4±0.4, sham vs BCAS; n=11–13, p<0.05; SHRSP: 0.6±0.05 vs 0.5±0.04 sham vs BCAS; n=16, p<0.05). The effects of BCAS on the parenchymal arteriole (PA) function were assessed by pressure myography. BCAS had no effect of myogenic tone generation in either rat strain. In both WKY rats and SHRSP, BCAS caused a marked impairment in carbachol mediated endothelium‐dependent dilation (% dilation, WKY: 29.6±8.1 vs −10.2±7.4, sham vs BCAS; n=5–7, p<0.05; SHRSP: 17.5±5.3 vs −0.22±2.9, sham vs BCAS; n=5–6 p<0.05). Recent studies from our lab suggest that transient receptor potential channel vanilloid 4 (TRPV4) mediates endothelium‐dependent dilation in PAs. To assess the effects of BCAS on TRPV4‐dependent dilation, we used GSK1016790A, a potent and selective TRPV4 agonist. We found that TRPV4‐mediated dilation in the WKY rats was significantly impaired post‐BCAS (% dilation, 93.5±3.3 vs 57.7±13.3 Sham vs BCAS; n=3–4, p<0.05); this effect was not observed in the SHRSP (% dilation, 57.2±1.6 vs 51.8±6.9 sham vs BCAS; n=5–6, p<0.05). Interestingly TRPV4‐mediated dilation was impaired in the sham hypertensive rats compared to the sham WKY rats suggesting that hypertension impacts TRPV4 function. Together these data indicate that impaired TRPV4‐mediated dilation may contribute to the cognitive decline observed with BCAS in normotensive rats but not in rats with sustained hypertension.

Support or Funding Information

Supported by 5P01HL070687‐12.
Role of Endothelin Type B Receptors in Microvascular Dysfunction Post‐partum in Women Who Have Had Preeclampsia
Authors: Stanhewicz Anna , Santhanam Lakshmi , Alexander Lacy
Published: November 2023

Women with a history of preeclampsia have increased cardiovascular disease risk, however the mechanisms responsible for this association remain unclear. Microvascular damage sustained during a preeclamptic pregnancy may persist post‐partum, despite the remission of the clinical symptoms of preeclampsia. One putative mechanism contributing to persistent microvessel dysfunction in these women is increased vasoconstrictor sensitivity to endothelin‐1 (ET‐1), is a reduction endothelin‐1 type B receptor‐(ETBR) mediated. We hypothesized that 1) women who have had preeclampsia (PreEC) would have a greater vasoconstrictor sensitivity to exogenous ET‐1 administration compared to control women who had a normal pregnancy (HC), and that 2) this increased sensitivity would be due to a reduction in ETBR‐mediated dilation (protocol 1). We further hypothesized that ETBR‐blockade would attenuate endothelium‐dependent dilation to the agonist acetylcholine (Ach) in HC, but not PreEC (protocol 2). Ten PreEC (31±2 yrs, 7±2 mos. post‐partum) and 10 HC (28±2 yrs, 7±2 mos. post‐partum) participated. In protocol 1, 3 intradermal microdialysis fibers were placed in the forearm skin for the graded infusion of ET‐1 (10−20 – 10−8M) alone, ET‐1 + 500nM BQ‐123 for ETAR‐blockade, or the graded infusion of sarofotoxin 6c (S6c; 10−12 – 10−5M). In protocol 2, 2 fibers were placed for the graded infusion of ACh (10−7 – 102 mM) alone, and ACh + 500nM BQ‐788 for ETBR‐blockade. In both protocols, red cell flux was measured over each site by laser‐Doppler flowmetry (LDF). Cutaneous vascular conductance was calculated (CVC=LDF/MAP) and normalized to baseline (%CVCbase; protocol 1) or maximal (%CVCmax, 28mM SNP and local heat, 43°C; protocol 2). PreEC had augmented vasoconstrictor sensitivity to ET‐1 (PreEC −16.0±0.3 vs. HC −13.7±0.4 logEC50, P=0.01). Protocol 1: PreEC demonstrated a reduced dilation response to selective ETBR stimulation with ET‐1 (ET+BQ‐123: PreEC 130±22 vs. HC 290±77 %CVCbase; P=0.04), and reduced dilator sensitivity to the ETBR selective agonist S6c (PreEC −8.0±0.4 vs HC −8.9±0.7 logEC50; P=0.04). Protocol 2: PreEC had attenuated endothelium‐dependent dilation (PreEC 68±5 vs. HC 92±2 %CVCmax; P<0.01). ETBR inhibition attenuated the microvascular dilation response to ACh in HC (ACh alone 92±2 vs. ACh+BQ‐788 81±2 %CVCmax; P<0.01) but not in PreEC (ACh alone 68±5 vs. ACh+BQ‐788 74±3 %CVCmax; P=0.28). Women who have had preeclampsia demonstrate augmented vasoconstrictor sensitivity to ET‐1, mediated by a reduced ETBR‐dependent dilation response. Furthermore, attenuated ETBR‐mediated dilation contributes to diminished endothelial function which persists post‐partum in women who have had preeclampsia.

Support or Funding Information

NIH F32 HL129677‐02 (Stanhewicz), R01 HL093238‐06 (Alexander)
Adiponectin Attenuates Hypertension‐Induced Vascular Remodeling through NHE‐1 Activity and LKB1/AMPK Signaling
Authors: Ghantous Crystal M , Radwan Zeina , Farhat Rima , Ghali Rana , Chaaya Nancy , Sabra Ramzi , Zeidan Asad
Published: November 2023

Introduction

Hypertension leads to vascular remodeling, affects circulating levels of leptin and adiponectin (APN), and is associated with increased sodium hydrogen exchanger isoform‐1 (NHE‐1) activity. The aim of this study is to investigate the vascular protective effects of APN during hypertension.

Hypothesis

Hypertension‐induced vascular smooth muscle cell (VSMC) remodeling is mediated by NHE‐1 activity, LKB1/AMPK signaling and attenuated by high APN/leptin ratio.

Methods

In order to study the effect of hypertension on VSMC remodeling, the in vivo rat model of angiotensin II (Ang II) infusion for 14 days and the in vitro model of mechanically stretching the rat portal vein (PV; with 1.2 gr weights due to the force‐length relationship normalized to the human force of stretch during hypertension and the longitudinal orientation of its VSMCs) were used. APN (10 μg/ml) and the selective NHE‐1 inhibitor cariporide (10 μM) were added to blood vessels. Activation of ERK1/2, AMPK and LKB1 in VSMCs was evaluated by Western blot. Leptin and APN expression was studied by Western blot, while ROS production was assessed by DHE staining.

Results

Stretching the PV for 10 min increased p‐ERK1/2 by 2.10 ± 0.25 fold (n=5, p<0.05) in VSMCs (as compared to unstretched PVs), while cariporide and APN attenuated stretch‐induced ERK1/2 phosphorylation. Mechanical stretch for 10 min significantly decreased LKB1 and AMPK activation by 0.44 ± 0.14 and 0.34 ± 0.07 fold, respectively (n=6, p<0.05). This effect was attenuated by cariporide, while APN increased p‐LKB1 and p‐AMPK in stretched PVs to 1.0 ± 0.11 and 0.60 ± 0.04 fold respectively (n=4, p<0.05).

Ang II‐infusion for 14 days increased leptin (1.48 ± 0.12 fold, n=4 p<0.05), decreased APN (0.86 ± 0.04 fold, n=6, p<0.05), and increased ROS (3.46 ± 0.07 fold, n=3, p<0.05) in PVs. Similar results were observed in the aortas of Ang II‐infused rats (leptin: 1.83 ± 0.36 fold; APN: 0.79 ± 0.06 fold; ROS: 1.54 ± 0.12 fold, n= 5, p<0.05) compared to sham‐operated rats.

Conclusion

APN attenuates mechanical stretch‐induced VSMC remodeling by activating the LKB1‐AMPK axis and inhibiting ERK1/2, which are mediated by NHE‐1 activity. Moreover, hypertension‐induced vascular remodeling is associated with higher leptin synthesis, lower APN synthesis, and higher ROS production in VSMCs.

Support or Funding Information

This work was supported by Medical Practice Plan (MPP), Faculty of Medicine at AUB, to AZ.
HIV‐1 Infection and Inflammation‐Related microRNAs
Authors: Hijmans Jamie , Levy Ma'ayan , Greiner Jared , Stauffer Brian , Connick Elizabeth , DeSouza Christopher
Published: November 2023

microRNAs (miRs) are short single stranded noncoding RNAs that are involved in the regulation of a number of physiological and pathological processes. miRs down regulate target gene expression post‐transcriptionally by degrading messenger RNA and/or by blocking translation. It is now recognized that miRs play a key role in regulating inflammatory processes underlying cardiovascular disease (CVD). For example, altered expression of specific miRs, such as, miR‐126, miR‐146a, miR‐150 and miR‐34a have been linked with heightened vascular inflammation, atherosclerosis and CVD risk. Human immunodeficiency virus (HIV)‐1 is associated with increased vascular inflammation and that is thought to contribute to greater CVD risk. The mechanisms underlying the heightened HIV‐1‐related inflammatory stress are not fully understood. It is currently unknown whether inflammation‐related miRs are dysregulated with HIV‐1‐infection. Accordingly, the aim of this study was to determine the influence of HIV‐1‐infection, independent of other risk factors, on circulating expression of miR‐34a, miR‐126, miR‐146a and miR‐150. A total of 25 sedentary, middle‐aged adults have been studied: 10 HIV‐1‐seronegative adults (8M/2F; age 37±4 yr; BMI: 24.6±3 kg/m2) and 15 HIV‐1‐seropositive adults on stable antiretroviral therapy (11M/4F; age 38±3 yr; BMI:25.0±3 kg/m2). All subjects were non‐obese, normotensive, normolipidemic, and free of overt cardiometabolic disease. Circulating expression of miRs was determined in plasma using standard RT‐PCR techniques with miR primers of interest. Expression was normalized to exogenous C. elegans miR‐39 and reported as relative expression in arbitrary units (AU). Circulating expression of anti‐inflammatory miRs: miR‐126 (0.36±.015 vs 1.16±0.45 AU), miR‐146a (0.75±0.27 vs 4.20±1.90 AU) and miR‐150 (0.19±0.0 vs 3.50±1.43AU) were markedly lower (~70%, 85%, and 95% respectively; P<0.05) in the HIV‐1‐seropositive group compared with the HIV‐1‐seroponegative group. Moreover, the pro‐inflammatory miR‐34 (0.5±0.25 vs 1.30±0.60 AU) was ~60% higher in the HIV‐1‐seropositive group compared with the HIV‐1‐seronegative groups. Lower expression of miR‐126, miR‐146a and miR‐150 is consistent with a proinflammatory and proatherogenic phenotype, as they are involved in limiting inflammatory pathways. In summary, these results suggest that dysregulation of key inflammation‐related miRs may underlie and promote the heightened inflammatory state associated with HIV‐1‐infection in adults.
STIM2 Contributes to the Proliferative Characteristics via Increasing Basal [Ca2+]cyt in Pulmonary Artery Smooth Muscle Cells from Patients with Idiopathic Pulmonary Arterial Hypertension
Authors: Song Shanshan , Carr Shane , Makino Ayako , Yuan Jason X.‐J.
Published: November 2023

In pulmonary arterial hypertension (PAH), excessive cell proliferation is a key mechanism that results in an obstructive vasculopathy. An increase in basal intracellular free Ca2+ concentration ([Ca2+]cyt) has been described in pulmonary artery smooth muscle cells (PASMCs) from patients with idiopathic PAH (IPAH) and explains the PASMCs proliferation. STIM2 is reported to be a feedback regulator that stabilizes basal [Ca2+]cyt. A selective up‐regulation of STIM2 has been observed in PASMCs from patients with IPAH and contributes to the transition of PASMCs from a contractile phenotype to proliferative phenotype in rats. The exact mechanism of STIM2‐mediated PASMC proliferation in PAH remains unclear. We hypothesized that the augmentation in cell proliferation can be explained in part by a STIM2‐mediated increase in basal [Ca2+]cyt. Compared with normal PASMCs, IPAH PASMCs had increased STIM2 expression and basal [Ca2+]cyt. Overexpression of STIM2 in normal PASMCs increased basal [Ca2+]cyt, phosphorylated‐Akt and mTOR levels, and enhanced the activation of CREB, STAT3 and NFATc2, which are Ca2+/calmodulin‐sensitive transcription factors, resulting in increased cell proliferation. Knockdown of STIM2 in IPAH PASMCs decreased basal [Ca2+]cyt, phosphorylated‐Akt and mTOR levels, and reduced the activation of CREB, STAT3 and NFATc2, leading to decreased cell proliferation. The generalized upregulation of STIM2 in human PAH may overload intracellular Ca2+ and be a therapeutic target and biomarker.

Support or Funding Information

This work was supported in part by the grants from the National Heart, Lung and Blood Institute of the National Institutes of Health (HL115014, HL066012 and HL125208).
Modulating heme biosynthesis, through the administration of exogenous aminolevulinic acid may attenuate monocrotaline induced‐pulmonary arterial hypertension
Authors: Alhawaj Raed , Ghadhanfar Elham , Cherian Susan
Published: November 2023

Pulmonary arterial hypertension (PAH) is a progressive disease that initiates in small pulmonary arteries and arterioles, which undergo persistent vasoconstriction and vascular remodeling. This process elevates vascular resistance, pulmonary arterial pressure and ultimately results in right heart hypertrophy and failure. PAH can be induced in rats through exposure to the pneumotoxin monocrotaline (MCT). Deregulation of heme biosynthesis, which might accompany/contribute to elevated mitochondrial/cytosolic reactive oxygen species (ROS) is thought to propagate MCT‐induced PAH disease process. Elevated oxidative stress can augment the redox‐sensitive proto‐oncogene c‐Src kinase in PASMCs and thus might drive vascular remodeling further through the (c‐Src‐STAT3) axis. By administering the biosynthetic precursor of heme, aminolevulinic acid (ALA), we aim to drive heme biosynthesis and probably attenuate oxidative stress‐induced c‐Src activation.
Metabolic Acidosis Inhibits Pulmonary Inflammation and Ameliorates Experimental Pulmonary Hypertension
Authors: Hudalla Hannes , Michael Zoe , Kourembanas Stella , Christou Helen
Published: November 2023

Introduction

Pulmonary inflammation contributes to the pathogenesis of pulmonary hypertension (PH). We previously reported that metabolic acidosis ameliorated experimental PH but the underlying mechanisms of protection are unknown. We hypothesized that treatment with Acetazolamide (ACTZ) or ammonium chloride (NH4Cl) may ameliorate Sugen/Hypoxia (SU/Hx)‐induced severe PH by modulating lung inflammation.

Methods

Male Sprague‐Dawley rats injected with Sugen (20 mg/kg,sc) or vehicle were exposed to normoxia or hypoxia (9%O2) for 3 weeks. As an early intervention, ACTZ (1.7mg/ml) or NH4Cl (1.5%) in the drinking water was given from week 1 to 3 (2 weeks). We assessed hemodynamics and right ventricular hypertrophy (RVH) (Fulton's Index, FI). Lungs, alveolar macrophages, pulmonary arteries (PA) and blood serum were collected for RT‐qPCR and ELISA. Pulmonary artery smooth muscle cells (PASMC) were treated with TNFα (10ng/ml) and de‐differentiation and proliferation was assessed by RT‐qPCR and proliferation assay. Bone marrow‐derived macrophages (BMDM) were polarized to M1 using LPS (100ng/ml) and INF‐γ (20ng/ml) for 6 or 24h and exposed to non‐hypercapnic acidosis at different pH (7.4, 7.0, 6.8) in vitro. Statistical analysis by ANOVA and Mean ±SEM values are presented.

Results

Both ACTZ‐ and NH4Cl‐treatment caused robust metabolic acidosis and significantly lowered RVSP and FI compared to untreated SU/Hx animals (RVSP: 42.47±2.95 vs ACTZ:27.81±2.97 or NH4Cl:28.61±1.23 mmHg, FI: 0.66±0.03 vs ACTZ:0.44±0.02 or NH4Cl:0.29±0.05). Expression of TNFα, IL‐6, and MCP‐1 of SU/Hx rats were significantly higher in whole lungs and alveolar macrophages from untreated SU/Hx rats compared to controls and serum levels of IL‐6 were also elevated. These changes were ameliorated in the two intervention groups. RT‐qPCR of pulmonary arteries revealed enhanced proliferation and de‐differentiation in untreated SU/Hx animals, and reversal in both intervention groups. In vitro we could demonstrate similar de‐differentiation and proliferation of PASMC upon TNFα treatment. In cultured BMDM, metabolic acidosis down regulated cytokine production (TNFα, IL‐6, and MCP‐1) in a pH‐dependent manner.

Conclusion

Metabolic acidosis induced by ACTZ or NH4Cl ameliorates PH and RVH in the SU/Hx model of severe PH and reduces the lung inflammatory response. pH dependency of cytokine production in macrophages may be a novel therapeutic approach in PH‐related inflammation.

Support or Funding Information

Funding: NIH 1R01 HL 116573 (to H.C.)
Arginase 2 knockout mice are protected against hypoxia‐induced pulmonary hypertension
Authors: Xue Jianjing , Nelin Leif D , Chen Bernadette
Published: November 2023

We have previously shown that hypoxia‐induced pulmonary artery smooth muscle cell proliferation depends on arginase 2 (arg2) induction. We hypothesized that deficiency of arginase 2 will be protective against pulmonary hypertension in a murine model of hypoxia‐induced pulmonary hypertension. Male and female heterozygous mice with a targeted mutation of Arg2 (B6.Cg‐Arg2tm1Weo/J, Arg2+/−; Jackson Laboratory, Bar Harbor, ME) were crossed. The littermate wild‐type (WT), Arg2+/+ controls and homozygous mutant Arg2−/− knockout (KO) mice (8–10 weeks‐old) were exposed to normoxia or normobaric hypoxia (10% O2) for 28 days. Consistent with previous reports, we demonstrate that WT mice exposed to 10% O2 for 28 days have right ventricular (RV) hypertrophy as evidenced by an increased RV/[left ventricle (LV)+septum (S)] ratio compared to mice exposed to 21% O2, a change of ~0.27 ± 0.04. This hypoxia‐induced increase in RV/(LV+S) is significantly blunted in Arg2 KO mice (0.15 ± 0.03, p < 0.05). Additionally, echocardiographic findings of elevated pulmonary artery pressures as evidenced by a decrease in pulmonary artery acceleration time (PAT)/pulmonary ejection time (PET) are seen in WT mice exposed to hypoxia compared to normoxia (0.213 ± 0.010 vs 0.263 ± 0.012, p < 0.01). There was no significant difference in PAT/PET in Arg2 KO mice exposed to hypoxia (0.248 ± 0.008) compared to WT (0.263 ± 0.012) or Arg2 KO mice (0.261 ± 0.008) exposed to normoxia. Our findings suggest that arginase 2 is critical in the pathogenesis of hypoxia‐induced pulmonary hypertension.

Support or Funding Information

5 K08 HL105677 05 BC
Characterizations of the Right Ventricle in Ovalbumin/Sugen Model of Pulmonary Arterial Hypertension
Authors: Shults Nataliia V. , Wang Xinhong , Suzuki Yuichiro
Published: November 2023

Right heart failure is the major cause of death among patients with pulmonary arterial hypertension (PAH). Thus, understanding the biology of the right ventricle (RV) should help developing new therapeutic strategies. Rats subjected to the injection of Sugen5416 (an inhibitors of vascular endothelial growth factor receptor) plus the ovalbumin immunization had increased pulmonary arterial pressure and severe pulmonary vascular remodeling. In this model, RVs of these PAH rats were hypertrophied and had severe cardiac fibrosis. No cardiac apoptosis was, however, detected. Metabolomics analysis revealed that oxidized glutathione, xanthine and uric acid had increased in PAH RVs, suggesting the production of reactive oxygen species by xanthine oxidase. PAH RVs were also found to have a 30‐fold lower level of a‐tocopherol nicotinate, consistent with oxidative stress decreasing antioxidants and also demonstrating for the first time that the nicotinate ester of vitamin E is endogenously expressed in the heart. Oxidative/nitrosative protein modifications including S‐glutathionylation, S‐nitrosylation and the nitrotyrosine formation, but not protein carbonylation, were found to be increased in RVs of rats with PAH. Mass spectrometry identified that S‐nitrosylated proteins include heat shock protein 90 and sarcoplasmic reticulum Ca2+‐ATPase. These results from the Ovalbumin/Sugen model of PAH revealed specific oxidative/nitrosative changes that are associated with RV failure.

Support or Funding Information

National Institutes of Health and National Natural Science Foundation of China
Short‐term Exposure to High Glucose Decreases Acetylcholine Sensitivity in Male Rat Pudendal Artery
Authors: Klee Nicole , Webb R Clinton
Published: November 2023

Sexual dysfunction is one of the most prevalent complications of diabetes. The combination of diabetes and sexual dysfunction affects family planning and overall quality of life, and sexual dysfunction is now considered an early marker for cardiovascular diseases. In diabetic males, erectile dysfunction is associated with impaired endothelium‐dependent vasodilation. Diabetes also increases the risk of female sexual dysfunction however, whether there is impaired endothelium function in females is less clear. The objective of this research is to determine if these distinct phenotypes of diabetes are modulated by testosterone. In the male, low testosterone is associated with hyperglycemia and erectile dysfunction and impaired endothelial function. In the female, high levels of testosterone are associated with hyperglycemia but no data exist characterizing mechanistic explanations for reduced clitoral blood flow responses. To test this hypothesis we used pudendal arteries (important source of blood flow to sexual tissues) from 12 week old Wistar male and female rats. Functional studies were performed in pudendal arterial rings mounted onto a myograph and incubated in high glucose (22 mM) for one hour in the presence or absence of testosterone (10−7 M). Concentration‐response curves were then performed in these tissues to phenylephrine (10−9 M‐10−4 M) and acetylcholine (10−9 M‐10−4 M). Male pudendal arteries incubated in high glucose exhibited a decreased sensitivity to acetylcholine. This suggests that short term exposure to high glucose induces responses which inhibit the vasodilater function in males.
Acute Radiation Exposure Damages the Intestinal Mucosa and Key Vasoregulatory Mechanisms
Authors: Hill Michael A. , Schmid‐Schönbein Geert W. , Maitz Charles A. , Yang Yan , Sun Zhe , Qiu Tianyi , Nourian Zahra , Meininger Gerald A.
Published: November 2023

Exposure to large doses of radiation leads to vascular abnormalities that impact morbidity and mortality. The mechanisms underlying this mode of vascular dysfunction are, however, uncertain. We hypothesize that radiation compromises the mucosal barrier properties of the small intestine allowing leakage of digestive enzymes into the vasculature exposing cells of the vessel wall to protease activity. To investigate this hypothesis mice were placed in a custom‐designed paraffin chamber and exposed to 8Gy radiation delivered by a Siemens Oncor clinical linear accelerator. Two and seven days after radiation exposure samples of small intestine (jejunum) were collected for histology while vascular smooth muscle cells (VSMC) were isolated for measurement of extracellular matrix protein (fibronectin) adhesion using atomic force microscopy (AFM) and K+ channel activity by patch clamp. A subset of mice was subjected to oral glucose tolerance tests as a measure of insulin resistance. At day 2, extensive damage to intestinal villi and crypts was evident, while repair occurred by day 7. In contrast, the muscularis remained intact at both time‐points. Coincident with intestinal damage there was decreased probability of binding of fibronectin‐coated AFM probes to VSMC and the voltage‐gated component of K+ (Kv) flux was significantly decreased. Further, mice exhibited impaired glucose tolerance at day 2 after exposure to radiation. To simulate exposure to pancreatic enzymes, VSMC were acutely treated with chymotrypsin (10 – 50U/ml; 5 mins). Similar adhesion and electrophysiology studies were performed. Consistent with the observations following radiation exposure, decreased binding of fibronectin and impaired Kv currents were again evident. Collectively, the data are consistent with acute radiation exposure leading to disruption of the intestinal mucosal permeability barrier allowing access of digestive proteases to the systemic circulation. A consequence of this is suggested to be autodigestion, and cleavage, of key vasoregulatory proteins including integrins, receptors and ion channel subunits.