bluuebunny/crossref_metadata_2025 huggingface dataset:
Proton Pump Inhibition Impairs Ventricular Remodeling in Infarcted Rats: Role of Superoxide‐DDAH Axis
Authors: Lee Tsung‐Ming , Chen Wei‐Ting
Published: November 2023

Proton pump inhibitors (PPIs) were frequently used for preventing or treating peptic ulcer. Recently, PPIs have been shown to increase the risk of myocardial infarction. The purpose of this study was to determine whether PPIs adversely affect ventricular remodeling in infarcted rats. Male Wistar rats were randomly assigned into either vehicle, omeprazole, omeprazole + vitamin C, omeprazole + olmesartan, or famotidine for 4 weeks starting 24 hours after ligation. Compared with vehicle‐treated infarcted rats, omeprazole‐treated infarcted rats had significant changes with reduced myocardial vitamin C levels, increased oxidant production, and decreased dimethylarginine dimethylaminohydrolase 2 (DDAH2) activity, which in turn increased asymmetric dimethylarginine (ADMA) levels and impaired ventricular remodeling. These changes were prevented by treatment with either vitamin C or olmesartan. For gastric protection similar to omeprazole, the H2 blocker famotidine had no effect on ventricular remodeling. In contrast to the in vivo results, the ex vivo study to show similar superoxide and DDAH2 protein levels between vehicle‐ and omeprazole‐treated infarcted rats suggested involvement of gastric vitamin C uptake in mediating the impaired axis of vitamin C‐superoxide‐DDAH2 in the in vivo measurement. Administration of PPI was associated with impaired DDAH2 expression and increased myocardial ADMA by reduced gastric vitamin C uptake, which impaired ventricular remodeling after infarction. These effects are prevented by coadministering vitamin C or olmesartan. Our results indicate that the superoxide‐DDAH2 axis could be a potential target for the treatment of ventricular remodeling.

Support or Funding Information

This work was supported by the grants of An‐Nan Hospital (ANHRF 104‐02), China Medical University (CMU103‐S‐07) and Ministry of Science and Technology (MOST 104‐2314‐B‐039‐021), Taiwan.
Requirement of extracellular Ca2+ in the maintenance of eNOS phosphorylation and function in endothelial cells
Authors: Luo Cindy L. , Xia Vivian Q. , Parinandi Narasimham L.
Published: November 2023

Nitric oxide (NO), produced by endothelial NO synthase (eNOS), plays central roles in cardiovascular regulation and disease. eNOS was previously thought to be activated by the rise of intracellular Ca2+. Recent studies demonstrated that eNOS function is also critically affected by protein phosphorylation. For example, phosphorylation of Ser1179/1177 (bovine/human) residue renders eNOS activation without the need of intracellular Ca2+ elevation. Our prior study show that intracellular Ca2+ released from endoplasmic reticulum triggers eNOS phosphorylation and activation. But whether and how extracellular Ca2+ affects eNOS phosphorylation is unknown. To address this question, cultured bovine endothelial cells were exposed to Ca2+‐free medium and the alterations of eNOS phosphorylation were measured. Extracellular Ca2+ removal induced a rapid loss of eNOS Ser1179 phosphorylation. In contrast, removing extracellular Mg2+ had little impact on eNOS Ser1179 phosphorylation. Loss of phosphorylation appeared to be a specific action to Ser1179 as the phosphorylation status of another eNOS reside, Ser635, was not altered. Parallel to the loss of Ser1179 phosphorylation, eNOS activity was markedly attenuated. Inhibiting the Ca2+/CaM‐dependent phosphatase calcineurin had no effect on eNOS Ser1179 dephosphorylation. Knocking down protein phosphatase 1 or 2A (PP1 or PP2A) individually failed to protect eNOS Ser1179 phosphorylation either. But the knockdown of PP1 and PP2A together prevented eNOS Ser1179 dephosphorylation in cells under Ca2+‐free condition. These studies reveal a previously unknown essentiality of extracellular Ca2+ in the maintenance of eNOS Ser1179 phosphorylation in endothelial cells. Extracellular Ca2+ deprivation results in eNOS Ser1179 dephosphorylation and loss of enzyme function. Both PP1 and PP2A, which may compensate each other, participate in eNOS Ser1179 dephosphorylation inside cells upon extracellular Ca2+ removal.
The Role of Toll‐Like Receptor 4 in the Development of Cardiomyocyte Hypertrophy in vitro: Participation of NF‐κB Signalling
Authors: Alvim Juliana Morais , da Silva Fernanda Gaisler , Carneiro‐Ramos Marcela Sorelli
Published: November 2023

Objectives

Toll like receptors (TLR), which plays an important role in innate immunity, inflammatory process and infection, activates the NF‐kB pathway and regulates inflammatory cytokines expression. Some systemic or local inflammations are followed by cardiovascular diseases, showing that this cytokines are responsible for modulating the cardiac tropism, decreasing the cardiac contractile. Studies using isolated cardiomyocytes allow a specific evaluation of the effects caused by the hypertrophic stimuli as well as the characterization of signalling pathway involved in this process. The aim of this study is to evaluate the role of Nf‐kB signaling in cardiomyocyte tropism after TLR activation.

Methods

Cardiomyocytes were isolated from wistar neonatal rats (in accordance with the ethical committee), presenting typical morphological and contractile characteristics that were maintained through the entire experiment. Cells were treated for 24hs with five different concentrations of LPS (TLR4 agonist) in order to define the dose that induces greater hypertrophic response. ANF and Alpha‐actin mRNA levels were used as cardiac hypertrophy markers. Gene expression was evaluated by Real‐time PCR. The results were expressed as mean ±SD and P<0.05.

Results

Alpha‐actin mRNA levels has increased approximately 50% after 100uM of LPS treatment compared with control group (p<0.05).

Conclusion

These results suggest that TLR4 was activated by their agonist and promoted cardiomyocytes hypertrophy in vitro.

Support or Funding Information

Financial support given by FAPESP, CAPES and UFABC.
Low Post‐ischemic Recovery of SIRT3 Deficient Mouse Heart is Not Associated with Oxidative Damage of Mitochondrial Proteins and Genome
Authors: Parodi‐Rullán Rebecca M , Rullán Pedro J , Chapa‐Dubocq Xavier R , Jang Sehwan , Javadov Sabzali
Published: November 2023

Background

Sirtuins are NAD+‐dependent deacetylases that regulate cell metabolism through protein acetylation/deacetylation. Among mitochondrial isoforms (SIRT3–5), SIRT3 is the major deacetylase. Recent studies demonstrated that SIRT3 can affect the activity of cyclophilin D (CyP‐D), a key regulator of the mitochondrial permeability transition pore (mPTP). mPTP opening occurs in response to oxidative stress due to increased mitochondrial Ca2+, Pi, and ROS, and initiates mitochondria‐mediated cell death. Hyperacetylation of CyP‐D due to downregulation of SIRT3 could lead to an increase in mPTP formation. Here, we elucidated the possible role of mitochondrial oxidative stress in cardiac dysfunction induced by ischemia‐reperfusion (IR) in SIRT3 knockout (SIRT3−/−) mice.

Methods

Male wild type (WT) and SIRT3−/− mice hearts were subjected to IR by the Langendorff‐mode perfusion in the presence or absence of the mPTP inhibitor, sanglifehrin A (SfA).

Results

Hearts of SIRT3−/− mice exhibited significantly (P<0.001) less recovery of cardiac function at the end of reperfusion when compared to WT mice. SfA had no protective effects on post‐ischemic recovery of WT and SIRT3−/− hearts. However, activity of lactate dehydrogenase, a marker for tissue damage, in the cardiac effluent was significantly (P<0.004) higher in SIRT3−/− mice compared to WT counterparts, and this effect was prevented by SfA during the first ten minutes of reperfusion. In addition, mitochondria from SIRT3−/− hearts exhibited high basal swelling (P<0.046), and Ca2+‐induced swelling was prevented by SfA in vitro in mitochondria from both WT and SIRT3−/− hearts. Ca2+‐stimulated hydrogen peroxide production was significantly (P<0.0003) higher in SIRT3−/− mitochondria but this effect was lost (P<0.005) in SIRT3−/− mitochondria from hearts perfused with SfA. Notably, carbonylation of mitochondrial proteins was not affected in SIRT3−/− liver. Mitochondria of SIRT3−/− liver showed increased acetylation of proteins (P<0.001), despite increased SIRT4 (P<0.0073) levels. Mitochondrial SOD (SOD2) expression in liver mitochondria of SIRT3−/− mice was higher (P<0.041) than that of WT. The protein level of the base excision repair enzyme, OGG‐1 that effectively removes DNA damage induced by oxidative stress was significantly (P< 0.01) increased in SIRT3−/− liver mitochondria and the integrity of mitochondrial DNA was not affected.

Conclusion

SIRT3 deficiency exacerbates cardiac dysfunction during post‐ischemic recovery, and increases mPTP and ROS generation without oxidative damage to mitochondrial proteins and DNA. Absence of SIRT3 leads to upregulation of mitochondrial SIRT4, SOD2, and OGG‐1 suggesting the development of a compensatory response in SIRT3−/− mice in order to preserve mitochondrial integrity.

Support or Funding Information

SC1HL118669 NHLBI NIH, and R25‐GM061838 MBRS‐RISE NIH Grants
Attenuation of Neointimal Formation with Netrin‐1 and Netrin‐1 Preconditioned Endothelial Progenitor Cells
Authors: Liu Norika Mengchia , Siu Kin Lung , Youn JiYoun , Cai Hua
Published: November 2023

Restenosis after angioplasty is a serious clinical problem that can result in reocclusion of the coronary artery. Although current drug eluting stents have proved to be more effective in reducing restenosis, they have drawbacks of inhibiting reendothelialization to promote thrombosis. New treatment options are in urgent need. We have shown that netrin‐1, an axon‐guiding protein, promotes angiogenesis and cardioprotection via production of nitric oxide (NO). The present study examined whether and how netrin‐1 attenuates neointimal formation in a femoral wire injury model. Infusion of netrin‐1 into C57BL/6 mice via an osmotic minipump markedly attenuated neointimal formation following wire injury of femoral arteries, measured by intimal to media ratio (from 1.94±0.55 to 0.45±0.86 at 4 weeks). This protective effect was absent in DCC+/− animals, which lack netrin‐1 receptor DCC. Vascular smooth muscle cell (VSMC) migration was significantly abrogated by netrin‐1, and this response was mediated by a NO/cGMP/p38 MAPK pathway. Proliferation of VSMC in situ was also largely attenuated by netrin‐1 treatment. Injection of netrin‐1 preconditioned endothelial progenitor cells (EPCs) significantly reduced neointimal formation, which was dependent on DCC presence on EPCs. Netrin‐1 significantly augmented EPC proliferation, NO production, and resistance to oxidative stress, implicating improved function of EPCs to participate in the repair process. In conclusion, these data indicate that netrin‐1 is highly effective in reducing neointimal formation following vascular endothelial injury, which is dependent on DCC, and attributed to inhibition of VSMC proliferation and migration as well as improved EPC function. These data may support usage of netrin‐1 and netrin‐1 preconditioned EPCs as novel therapies for post‐angioplasty restenosis.

Support or Funding Information

HL077440
C21, an AT2R agonist, arrests the progression of bleomycin‐induced pulmonary fibrosis and associated cardiac dysfunctions
Authors: Rathinasabapathy Anandharajan , Horowitz Alana , Kumar Ashok , Horton Kelsey , Martinez Diana , Raizada Mohan , Steckelings Ulrike Muscha , Unger Thomas , Sumners Colin , Shenoy Vinayak , Katovich Michael
Published: November 2023

Pulmonary Fibrosis (PF) is a chronic, lethal interstitial lung disease with a median survival of less than 3 years after the onset of disease. PF related mortality necessitates the identification of newer therapeutic targets. We recently observed an imbalance of renin angiotensin system in the pathology of pulmonary hypertension (PH) and demonstrated that utilization of an agonist of the angiotensin type II receptor (AT2R) was therapeutically efficacious in not only reducing pulmonary pressure in a rodent model of PH, but it also significantly reduced both pulmonary and cardiac fibrosis in this model. Thus we decided to investigate the therapeutic efficacy of Compound 21, C21, an AT2R agonist, in the treatment of PF. A single instillation of Bleomycin (Bleo) in 8‐weeks old rats was used to induce PF. Two weeks after Bleo instillation, Picro Sirius and H&E staining demonstrated significant lung fibrosis (2.99±0.277 vs 17.30±1.36, % of area) and tissue remodeling (1.65±0.183 vs 6.35±0.259, Ashcroft Score). Likewise, hydroxyproline assay demonstrated significant accumulation of collagen in the Bleo‐treated animals (1.82±0.131 vs 4.09±0.665, mM). Extensive tissue remodeling and fibrosis eventually resulted in secondary pulmonary hypertension in the Bleo animals (RVSP; 29.44±0.711 vs 45.72±2.52, mmHg) with concomitant right ventricular hypertrophy (RVH = RV/LV+S; 0.267±0.011 vs 0.400±0.019, wt/wt). Echocardiography (ECHO) assessment demonstrated that ratio of RV/LV (End diastolic Area; 0.307±0.015 vs 0.590±0.034, cm2/cm2 and Ejection Fraction; 0.727±0.014 vs 0.499±0.020, %/%) were significantly dysregulated in the Bleo animals. Two C21 protocols were evaluated. In one (prevention protocol), C21 (0.03 mg/kg) was administered daily for the entire 2 weeks, while in the other (reversal protocol) it was administered after 3 days of Bleo instillation when significant fibrosis and lung tissue remodeling was observed (Picro Sirius; 2.18±0.086 vs 6.58±0.742, % of area and H&E; 1.20±0.079 vs 3.58±0.159, Ashcroft Score). Significant attenuation of lung tissue remodeling, fibrosis, and collagen deposition was observed in both C21 treatment protocols. Furthermore, ventricular hemodynamics (RVSP) and cardiac functions (RVH, RV/LV EDA and EF) were also significantly attenuated in Bleo animals treated with C21. Collectively, the present study demonstrated that the AT2R agonist, C21, arrested the progression of PF and the associated cardiac dysfunctions and provides necessary evidence to move forward with a possible AT2R‐mediated therapeutic intervention for the treatment of PF.

Support or Funding Information

This work was supported by NIH grants HL102033, HL056921 and American Heart Association Scientist Development Grant SDG12080302
Upregulation of TSP‐1 Expression Associates with Enhanced Phenotypic Switching of Vascular Smooth Muscle Cells in KKAy+/− Mice, A Mouse Model of Metabolic Syndrome
Authors: Sahu Soumyadip , Ganguly Rituparna , Raman Priya
Published: November 2023

Metabolic syndrome (MetS) refers to a constellation of risk factors that include insulin resistance, abdominal obesity, hyperglycemia, hypertension and dyslipidemia. Atherosclerotic complications are the leading cause of increased morbidity and mortality in MetS. Individuals with MetS have an increased propensity for abnormal migration and proliferation of vascular smooth muscle cells (VSMCs), a key step responsible for development and progression of atherosclerosis. We previously reported that high glucose and high leptin concentrations, characteristic of MetS, upregulate the expression of a potent proatherogenic matricellular protein thrombospondin‐1 (TSP‐1) in human and mouse aortic smooth muscle cells. Multiple epidemiological and animal studies document an important role of TSP‐1 in development of atherosclerosis. TSP‐1 expression is significantly elevated in both diabetic and obese patients and animal models. Previous studies suggest that TSP‐1 stimulates VSMC migration and proliferation which may contribute to accelerated atherosclerotic and restenotic complications. The goal of the present study was to investigate whether upregulation of TSP‐1 expression correlates with enhanced VSMC phenotypic switching in the agouti yellow KKAy+/− mice, a mouse model of MetS characterized by hyperglycemia, obesity and hyperleptinemia. Briefly, yellow obese, hyperglycemic KKAy+/− mice and age‐matched black lean, non‐hyperglycemic littermates (KKAy−/−), weaned at 4 wks of age were maintained on regular chow diet until 24 wks of age (study endpoint). After an overnight fasting, mice were euthanized at endpoint to harvest blood and aortic vessels; plasma samples were processed for lipid measurements and aortic tissue lysates were subjected to immunoblotting. Yellow KKAy+/− mice showed a significant increase in body weight, blood glucose, total cholesterol and total triglyceride levels as compared to black KKAy−/− littermate mice. Immunoblotting of aortic tissue lysates revealed an upregulation of TSP‐1 expression concomitant to increased expression of PCNA (proliferation marker) in obese KKAy+/− mice as compared to age‐matched lean KKAy−/− littermates. There was an increased expression of vimentin (synthetic SMC marker) coupled with reduced SM‐MHC (contractile SMC marker) expression in the aortic vessels of obese KKAy+/− mice as compared to the lean KKAy−/− mice. Finally, immunoblotting experiments further demonstrated increased activation of ERK‐1/2 and p38‐MAPK, signaling mediators of VSMC growth, in aortic vessels of obese KKAy+/− mice as compared to lean KKAy−/− littermates. Taken together, our data suggest a potential link between TSP‐1 and VSMC phenotypic transition that may contribute to atherosclerotic complications associated with metabolic syndrome.
Influence of the cold pressor test upon aortic pulse wave reflection in individuals with increased arterial stiffness
Authors: Pearson James , Borner Anastasia , Murray Kyle
Published: November 2023

Aortic pulse wave reflection is an indicator of LV after load, myocardial O2 demand and a predictor of cardiovascular events and is partly determined by muscular and elastic artery stiffness and pulse wave velocity. Acute stimulation of the sympathetic nervous system increases the vascular resistance of the muscular arteries thereby influencing arterial stiffness. The aim of this study was to examine the influence of acute sympathetic stimulation via the cold pressor test upon aortic pulse wave reflection in individuals with and without increased arterial stiffness. Eleven participants (4 males, 31±12yrs; 172±10cm; 75±15kg) completed a cold pressor test (CPT) wherein the left hand was immersed up to the wrist in 2–4°C water for 3 minutes. Blood pressure (mean arterial pressure; MAP) and pulse wave reflection (radial tonometry) were measured throughout. Stroke volume was calculated (photoplethysmography; NexFin) and heart rate measured (ECG; HR) throughout to provide cardiac output (Q). Aortic pulse wave velocity was measured before the CPT (Mobil‐O‐Graph®; aPWV). Pulse wave reflection was referenced to a heart rate of 75 bpm (augmentation index; Aix75). At baseline heart rate was 66±8 bpm and the change during CPT was variable between participants (Range: −11 to +14 bpm). Prior to CPT, Aix75 was 0±19% (Range −31 to 31%) and MAP was 87±10 mmHg. During the CPT Aix75 increased to 17±13% while MAP increased to 102±7 mmHg (both P ≤ 0.05). The change in Aix75 during CPT correlated poorly with age (R2 = 0.13), baseline MAP (R2 = 0.03), the change in MAP during CPT (R2 = 0.05) and baseline aPWV (R2 = 0.08) (all P > 0.05). However, the increase in Aix75 during the CPT correlated moderately with baseline Aix75 (R2 = 0.75; P = 0.0006) and the change in Q during CPT (R2 = 0.40; P = 0.049). Increases in aortic pulse wave reflection during the cold pressor test were inversely related to baseline aortic pulse wave reflection. This may be indicative of a ceiling effect where individuals with evidence of existing arterial stiffening demonstrate a reduced increase in pulse wave reflection during sympathetic stimulation via cold pressor test. Nevertheless individuals with evidence of increased arterial stiffness still experience acute increases in pulse wave reflection during sympathetic stimulation via the cold pressor test.
Late Effects of Early Anthracycline‐Induced Cardiotoxicity in Pediatric Mouse Model
Authors: Harris Tanoya L , Andrews Thomas , Aune Gregory J
Published: November 2023

Objective

Childhood cancer survivors with a history of anthracycline exposure have a 2 – 5 fold increased risk of developing cardiovascular disease as adults. Elucidating the molecular and cellular mechanisms responsible for pathological changes in the heart has proved challenging. The lack of available myocardial tissue available to study is hampered by long latent period between childhood exposure and onset of overt disease. The goal of this study was to use a mouse model that simulates early anthracycline exposure and evaluate cardiac endpoints throughout lifespan to study the long‐term cardiovascular effects of anthracycline treatment.

Methods

At 2 weeks of age mice were expos ed to 5 weekly intraperitoneal (i.p.) injections of saline or the anthracycline doxorubicin at 1 mg/kg, 3 mg/kg or, 5 mg/kg. Cardiovascular function was analyzed during acute doxorubicin exposure (3, 5, 7 weeks). Survival and body weight were monitored throughout lifespan. At 15 months, animals were sacrificed and 60 common serum inflammatory and metabolic mediators were quantified in control and anthracycline‐exposed mice. Western blots were performed with whole heart tissue lysates and probed for STAT3 and p‐STAT3.

Results

Early and Late toxicity were consistently elicited at all doxorubicin doses administered as indicated by decreased fractional shortening (F.S.), left ventricular and (LV) mass. Survival and body weight were decreased with higher doses of anthracycline. Of the metabolic and inflammatory mediators assayed in serum, 13 were significantly decreased (P<0.05) in doxorubicin treated animals compared to controls. In contrast, leptin was markedly increased (P<0.02) in mice treated with doxorubicin as compared to controls. Western blot analysis showed increased expression of p‐STAT3 which increased with higher doses of anthracycline compared to control.

Conclusion

Using a mouse model that emulates cardiotoxicity in children elicits relevant systematic metabolic changes. These data suggest that leptin and STAT3 are activated in correlation with cardiac dysfunction during the long recovery phase. STAT3 activation may be in response to higher circulating levels. Further evaluation must be performed. Myocardial tissue isolated from anthracycline treated mice may be used to develop a novel understanding of molecular and cellular mechanisms that drive the pathogenesis of cardiac disease in childhood cancer survivors.

Support or Funding Information

National Research Service Award (NRSA) NIH Training Grant T32‐HL007446
Low‐intensity exercise training improves autonomic modulation and cardiac function in a potential model of Gulf War illness in mice with organophosphate (DFP) exposure: analyze by noninvasive method of cardiovascular measures
Authors: Machi Jacqueline Freire , Conti Filipe , Hernandez Diana , Salgueiro Luis , Klimas Nancy , Fletcher Mary Ann , Morris Mariana
Published: November 2023

Background

Several conditions and exposures have been hypothesized to serve as instigating events that precipitated the recurring/ chronic symptoms associated with Gulf War illness (GWI). Our group was focused on the use of DFP as chemicals which can be used to produce models of GWI.

Purpose

The objective in this new study was the determination of the influence of DFP on cardiac (Echo), autonomic (spectral analysis) parameters in association with long term exercise training (6 months).

Methods

Male mice were divided into (n=8/group): Sedentary (S) and trained (T) groups. The exercise training was performed on an electronic wheel at low intensity for 1 h a day, 5 days/wk for 6 months. We used sc injection of DFP with dose of 1.5 mg/kg after 6 months of exercise program. Heart rate was recorded using the electronic platform provided by the echocardiography machine. The mice were kept under anesthesia (Isoflurane, 2 – 2.5% on 0.8l/min of O2) and positioned on the board with ECG sensors. The cardiac autonomic modulation was evaluated by spectral analysis. Cardiac function was assessed by echocardiography.

Results

T group showed better diastolic function with lower isovolumetric relaxation time (IVRT) (T: 14.5±0.3 vs S: 17.2±0.8 ms), E wave deceleration time (Desac. E) (T: 30.7±3 vs S: 15±0.91 ms), and cardiac global function by the myocardial performance index MPI (T: 0.29±0.007 vs S: 0.52±0.07). Regard to morphological parameters such as end diastolic diameter (EDD: T: 0.36±0.008 vs S: 0.32±0.008) end systolic diameter (ESD: T: 0.20±0.01 vs S: 0.15±0.01) and Left ventricular mass (LVM: T: 0.17±0.01 vs S: 0.13±0.007) were increased in T group compared to S group. Finally sympathetic modulation (LF) was lower in T groups (T: 24± 3 %) compared to S group (S: 40±4%). Vagal modulation was similar between both groups (T: 18±4 vs S: 30±7 %) as well as LF/HF ratio (T: 2.1±0.4 vs S: 1.5±0.3 beats/min).

Conclusion

Our findings demonstrated that Low‐intensity exercise training coupled with organophosphate exposure reduced sympathetic modulation and improved cardiac function which could result in an improved quality of life and longevity of this population.

Support or Funding Information

Award Number: W81XWH‐13‐2‐0085
Distribution of cardiac output to the brain across the lifespan
Authors: Xing Changyang , Tarumi Takashi , Yuan Lijun , Zhang Rong
Published: November 2023

Background

Brain has a high aerobic metabolic rate. Under resting conditions, about 15~20% of cardiac output (CO) is received by the brain in healthy young adults. However, it is unclear if the distribution of CO to the brain alters across the lifespan. The purpose of this study was to measure the cerebral blood flow (CBF)/CO ratio index (CCRI) in sedentary healthy individuals with age between 21 to 80 years.

Methods and Results

CBF and CO were measured in 139 subjects (women 88) using phase‐contrast magnetic resonance imaging (MRI) and echocardiography. CCRI was calculated as the percentage of CBF to CO. Body mass index (BMI), cardiac systolic function (eject fraction, EF), central arterial stiffness (carotid‐femoral pulse wave velocity, cfPWV), blood pressure, heart rate (HR), physical fitness (VO2 max) were measured to assess their potential influences on the CO‐CBF relationship. Both CBF and CCRI decreased with age (P<0.001) while CO remained unchanged (P=0.829). Women had higher CBF and CCRI than men (P<0.001). Univariate correlation analysis showed that BMI, cfPWV and blood pressure had negative correlations with CCRI (P<0.01). Multivariable analysis adjusted for sex, age and age2 showed that only BMI was negatively correlated with CCRI (β=−0.35, P<0.001).

Conclusion

The fraction of cardiac output distributed to the brain was reduced with normal aging and was affected significantly by BMI. These findings provide new insights for understanding the heart‐brain relationship and has potential clinical significance for brain health with aging.

Support or Funding Information

This study was supported in part by the NIH grants of RC1AG036003, R01HL102457 and China Scholarship Council Fund.
EndoGear 2 ‐ The Next Generation: A Fully Implantable Biotelemetry System to Measure Ultrasonic Transit‐Time Flow, Pressure and ECG in Cardiovascular Research Animal Models
Authors: Rotar Viorel , Garg Vikas , Milanowski Jan , Pitsillides Koullis
Published: November 2023

Animal model development and use requires the measurement of physiological parameters to verify model development and to determine treatment response. Such measurements of physiological data that include blood flow, blood pressure and ECG provide a more complete picture of the cardiovascular system. We have developed a totally implantable biotelemetry system that is capable of volumetric blood flow based on the ultrasonic transit‐time flow measurement principle, blood pressure and ECG measurements from unrestrained animals. The blood flowmeter section of the implant was designed around a custom developed ASIC, that incorporates many of the functions needed for implementing a low power transit‐time flowmeter. This miniature transit‐time flowmeter accepts Transonic© volumetric flowprobes for a variety of blood flow measurements such as Cardiac Output, coronary artery flow, renal flow etc. Blood pressure is measured with solid‐state pressure catheters for best data fidelity. The implant is about 18cc in volume and a battery is about 25cc in volume, so it can be used in animals over 3.5kg. Continuous measurement transmission of this implant is about a month, but this can be greatly extended when used in Timed‐Acquisition mode, where the implant is turned ON and OFF automatically by the supplied control software. Additional innovations of this new biotelemetry system include bidirectional RF control, implant ID and implantable connectors to enable user replaceable sensors and battery.
Selenophosphate Synthetase 1 is an Essential Protein with Roles in Regulation of Redox Homeostasis and in Malignancy in Mouse Cells
Authors: Na Ji‐woon , Tobe Ryuta , Carlson Bradley A , Huh Jang Hoe , Tsuji Petra A , Bang Jeyoung , Schweizer Ulrich , Gladyshev Vadim N , Hatfield Dolph L , Lee Byeong Jae
Published: November 2023

Selenophosphate is the active donor of selenium in the biosynthesis of selenocysteine (Sec), which is the 21st amino acid in the genetic code, and is synthesized from selenium and ATP by selenophosphate synthetase (SPS). In higher eukaryotes, there are two isoforms of SPS, SPS1 and SPS2. SPS2 catalyzes the synthesis of selenophosphate, while the function of SPS1 is largely unknown. To examine the role of SPS1 in mammals, we targeted the removal of SPS1 in F9 cells, a mouse embryonal carcinoma cell line, which led to growth retardation similarly as previously observed in SPS1‐deficient Drosophila and human cells. Transcriptome analysis showed that SPS1 deficiency significantly affected expression of a large number of mRNAs involved in cancer, embryonic development and the glutathione system. Particularly, the levels of glutaredoxin 1 (GLRX1) and glutathione‐S‐transferase omega 1 were extremely decreased. As expected from the change in gene expression pattern, reactive oxygen species (ROS) were accumulated, and malignant cancer properties (e.g., cell invasion and foci formation) were inhibited by SPS1 deficiency. Interestingly, overexpression of human GLRX1 in SPS1 deficient F9 cells reversed those phenotypes (ROS accumulation and retardation of cell invasion) induced by SPS1 knockdown. Our results suggest that SPS1 is an essential mammalian enzyme with roles in regulating redox homeostasis and controlling cell growth.
Measurement of Myocardial Microvascular PO2: Impact of Sumatriptan
Authors: Dobard Sarah E , Batten Spencer M , Cammack Scott A , Buell Joshua H , Sexton William L
Published: November 2023

Triptan drugs are commonly used in the treatment of migraine. As 5‐HT1B/D receptor agonists, these drugs relieve the effect of migraine through cerebral vasoconstriction. Concern has been noted that triptan drugs may precipitate adverse effects in the coronary circulation. However, there are limited methods with which to assess the real‐time impact of such drugs on the coronary circulation. We have developed a method to measure the microvascular partial pressure of oxygen (PO2mv) in the beating rat heart, in situ. PO2mv was measured using the phosphorescence quenching method which reflects the real‐time balance between oxygen delivery (QO2) and oxygen consumption (VO2). Briefly, female Sprague‐Dawley rats (n=5, 266 ± 3 g) were anesthetized with pentobarbital sodium (50 mg/kg ip). A tracheal cannula was inserted and the carotid artery and jugular vein were cannulated to monitor mean arterial pressure (MAP) and infuse drugs, respectively. A left lateral thoracotomy exposed the heart and ventilation was initiated (3 ml at 70 breaths/min; arterial PCO2 45 ± 5 and PO2 71 ± 3 mmHg). The apex of the heart was stabilized using a fine monofilament suture. The G4 phophor (30 μl) was infused via the jugular vein to permit measurement of PO2mv in the left ventricular free wall of the beating heart under control conditions and during interventions. Left ventricular PO2mv averaged 59 ± 7 mmHg and mean arterial pressure (MAP) was 118 ± 15 mmHg. To validate the responsiveness of this system, a bolus of isoproterenol (30 μg/kg iv; n=3) was infused as a positive control. Isoproterenol resulted in a dramatic fall in both PO2mv (−29 ± 10 mmHg) and MAP (−74 ± 20 mmHg). The time for PO2mv to recover to 50% of baseline was 145 ± 58 s. As a negative control, infusion of an equivalent volume of normal saline vehicle (n=2) had no effect on either PO2mv or MAP. In response to an infusion of sumatriptan (0.33 mg/kg iv; n=5) PO2mv fell 13 ± 3 mmHg (from 55 ± 7 mmHg) and MAP fell 40 ± 17 mmHg (from 108 ± 24 mmHg). The time for PO2mv to recover to 50% of baseline was 79 ± 18 s. In conclusion, we were able to measure PO2mv in the beating rat heart. Preliminary findings revealed that infusion of sumatriptan resulted in a reduction in PO2mv presumably reflecting a decrease in myocardial oxygen delivery (QO2). This reduction in myocardial PO2mv may impair myocardial function, especially in those with an already compromised coronary microvasculature.

Support or Funding Information

Supported by a grant from the Graduate Program Committee, KCOM – ATSU.
PTP1B in Calpain Dependent Feedback Regulation of VEGFR2 in Endothelial Cells: Implication in VEGF‐Dependent Angiogenesis and Diabetic Wound Healing
Authors: Zhang Yixuan , Li Qiang , Youn Jiyoun , Cai Hua
Published: November 2023

The VEGF/VEGFR2/Akt/eNOS/NO pathway is essential to VEGF‐induced angiogenesis. We have previously discovered a novel role of calpain in mediating VEGF‐induced PI3K/AMPK/Akt/eNOS activation through Ezrin. Here, we sought to identify possible feedback regulation of VEGFR2 by calpain via cleavage and activation of its substrate protein phosphotyrosine phosphatase 1B (PTP1B), and the relevance of this pathway to VEGF‐induced angiogenesis, especially in diabetic wound healing. Over‐expression of PTP1B inhibited VEGF‐induced VEGFR2 and Akt phosphorylation in bovine aortic endothelial cells (BAECs), while PTP1B siRNA increased both VEGFR2 and Akt phosphorylation in response to VEGF stimulation. Calpain inhibitor induced VEGFR2 activation can be completely blocked by PTP1B over‐expression. These data implicate calpain/PTP1B feedback regulation of VEGFR2. We next examined a potential role of PTP1B in VEGF‐induced angiogenesis. Endothelial cells transfected with PTP1B siRNA showed faster wound closure in response to VEGF. Aortic discs isolated from PTP1B siRNA transfected mice also had augmented endothelial outgrowth. To further define the role of PTP1B in physiological angiogenesis in vivo, wound healing assay in diabetic mice was carried out. Furthermore, we found that PTP1B over‐expression or calpain inhibition significantly deteriorated wound healing in STZ‐induced diabetic mice. In conclusion, our data for the first time demonstrate a calpain/PTP1B/VEGFR2 negative feedback loop. A critical role of PTP1B as a negative regulator in VEGF‐induced angiogenesis is revealed. Modulation of local calpain and PTP1B activities may prove beneficial in the treatment of defective wound healing in diabetes.

Support or Funding Information

This study has been supported by National Heart, Lung and Blood Institute (HL088975).
A Novel Rat Model of Chronic Thromboembolic Pulmonary Hypertension
Authors: Neves Evandro Neto , Brown Mary Beth , Zaretskaia Maria , Goodwill Adam , Kline Jeffrey
Published: November 2023

Chronic thromboembolic pulmonary hypertension (CTEPH) pathophysiology is still unclear and deserves more attention. There is a lack of animal models which replicate major pathogenesis of human CTEPH. We hypothesized that the combination of two deleterious insults would be required to damage the pulmonary vasculature and produce sustained pulmonary hypertension and right ventricular (RV) dysfunction found in human CTEPH.

CTEPH was induced in Sprague‐Dawley rats (400–450 g) with a combination of microspheres (221.000/100g, 85 μm, i.v.) and VEGF receptor antagonist (SU 5416, 20mg/kg, s.c.) in the PE+SU group. Additional groups received volume‐matched saline (SHAM), microspheres (PE) or SU5416 (SU) separately. CTEPH rats exhibited sustained pulmonary hypertension (RV systolic pressure, 62±12 and 53±9 mmHg at 3 and 6 weeks, respectively) compared to the Sham group (26±2 and 25±2 mmHg). Echocardiography showed robust RV dysfunction, hypertrophy and decreased cardiac output after CTEPH (P<0.05). Similarly, impaired RV contractile function (developed pressure and dP/dtmax) was observed by Langendorff's technique and was accompanied by increased RV mass in PE+SU group (>2 fold compared to Sham group, P<0.05). Approximately 25% decrement in aerobic capacity was observed in rats in PE and PE+SU groups after 3 days post‐injection. While more robust decreases were found after three (40%) and six (32%) weeks in PE+SU group, rats in PE group had their aerobic capacity recovered (P<0.05). Abundant lung vascularization can be observed in the PE group, whereas lung vascular rarefaction along with elevated endothelial injury makers were found in PE+SU group.

We conclude that at least two injuries are required to replicate pulmonary obstruction and microvasculature injury to reproduce CTEPH in rats. Interestingly, progressive PH, RV dysfunction and marked hypertrophy were found associated with deficient lung vascularization in our rat model.

Support or Funding Information

AHA 14POST20170013 (E Neves PI). This study was made possible by the Lilly Endowment, Inc. Physician Scientist (J Kline PI).
The Blurry Vision Project
Authors: Biro Mark P , Brantley Thomas , Freeman Barbara
Published: November 2023

Background/Objective

Neuroanatomy students traditionally learn the visual pathway, along with other neurologic pathways, in a two‐dimensional format. This approach is widely used but not thoroughly tested against other methods of learning. The experimental objective was to use the visual pathway as a platform to compare learning methods using a two‐dimensional approach versus a novel three‐dimensional model.

Methods

Thirty‐four students from the neuroanatomy course offered at the Case Western Reserve School of Medicine were recruited for the study. Subjects represented a number of graduate programs including the medical school, masters of anatomy, speech language pathology, biomedical engineering and neuroscience doctorate program. These students were separated into control and experimental groups prior to the experiment. The control group consisted of 13 students and the experimental group had 21 students. Each group completed a similar lesson plan reviewing components of the visual pathway and visual deficits secondary to lesions in the pathway. The control group used pencil and paper to reconstruct and explore the visual pathway, while the experimental group followed along with a three‐dimensional model of the visual pathway. Students in each experimental limb worked in groups of three to four students and given forty minutes to complete the first portion of the experiment. Upon completion, students were provided 20 minutes to individually take a quiz composed of fifteen multiple‐choice questions and a five question Likert scale questionnaire regarding their experience.

Data

All data was compared using two‐tailed t‐tests for independent samples and significance determined by p‐value < .05. Objective data from the experiment indicated students in experimental limb had higher mean scores (10.71) than control students (8.92) and outperformed them on twelve of fifteen total questions (all but 5,9 & 12), but these values only approached significance. Subjectively students from the experimental group had higher mean values for Likert scale questionairres (21.14 vs 19.84) and higher means on all individual questions, but similarly values only approached significance. Additionally, experimental groups had a 105% attendance rate, whereas the control group had 62% attendance rate.

Conclusions

From the experiment it cannot be concluded that students preformed significantly better in the three‐dimensional construct group compared to the two‐dimensional learning approach, despite higher mean subjective and objective data. This may in part due to overrepresentation of the experimental group and limited power of the experiment. Future experiments with a larger student population and additional subjective and objective questions will be necessary to determine if this novel three‐dimensional model approach to neuroanatomy education is superior to traditional approaches.

Support or Funding Information

Support for the experiment was provided by the Case Western Reserve University School of Medicine.
A Novel Model of Obstructive Sleep Apnea for Studying Cardiovascular Disease
Authors: Heintz Timothy , Lux Jacob , McLerie Meredith , Durgan David J , Panama Brian K
Published: November 2023

Background

Obstructive sleep apnea (OSA) is associated with cardiovascular disease. OSA is characterized by transient upper airway closures during sleep (apneas), and up to 24% of adults in the United States have OSA, many of whom are unaware of their condition. Patients with OSA exhibit daytime sleepiness, may have mood disorders, and are at increased risk for arrhythmias, such as a trial fibrillation. Despite the association between OSA and cardiac disease the specific mechanisms remain elusive. We have initiated a recently developed novel rat model of OSA which closely recapitulates the human condition by incorporating true apneas. Our goal was to examine the effects of OSA on several genes associated with cardiac fibrosis.

Methods and Results

To generate our OSA model, a silicone balloon was surgically implanted in the trachea of a rat (aged 45–70 days). To produce apneas, the balloon was inflated to transiently obstruct the airway. Unanesthetized, freely‐ranging rats were randomly given sixty 10‐second obstructions (apneas) per hour during their sleep phase (09:00–17:00) for 14 days. Control rats had obstruction devices implanted but the balloons were not inflated. Balloon inflations caused decreases in O2 saturations in OSA rats from 95.6±0.2% to 74.8±1.2%, and there were no differences in O2 saturations when balloons were deflated. O2 saturation decreases caused by apneas were also consistent throughout the experimental period. Measurements of mRNA from the ventricles after two weeks of OSA showed 2‐fold increases in the inflammatory cytokines TNF‐α and TGFβ‐2.

Conclusions

OSA is associated with increased cardiac expression of genes implicated in cardiac pathology. Our data demonstrates the utility of this novel rat model to study OSA‐induced cardiac disease.
Maternal High‐fat Diet and Diabetes Impairs Cardiac Metabolism and Mitochondrial Dynamics in Adult Offspring of Diabetic Pregnancy
Authors: Mdaki Kennedy S , Larsen Tricia D , Louwagie Eli J , Baack Michelle L
Published: November 2023

Background

Offspring of diabetic mothers are at risk of cardiovascular disease at birth and throughout life. We recently reported that maternal high‐fat (HF) diet impairs cardiac function in newborn offspring of diabetic pregnancy through metabolic stress and mitochondrial dysfunction. Whether this in utero exposure to maternal hyperglycemia and dyslipidemia can have lasting consequences on the developing heart is still unknown.

Objective

To determine the long‐term effects of prenatal exposure to maternal diabetes and high‐fat (HF) diet on cardiac metabolism in the adult offspring.

Methods

Female Sprague Dawley rats received controlled (CD) or HF diet throughout the study. At gestational day 14, dams were injected with either citrate buffer (CB) placebo or streptozotocin (STZ) to induce diabetes producing offspring from the following groups: controls (CD‐CB), diabetic exposed (CD‐STZ), HF exposed (HF‐CB), and combination exposed (HF‐STZ). Litters were culled to equal size and pups were cross‐fostered to normal dams. Cellular bioenergetics, oxidative injury, and mitochondrial dynamics were evaluated using Seahorse® XF24 analyses, malondialdehyde assay, and confocal live cell imaging of primary isolated cardiomyocytes from offspring at 6 months of age. Outcomes were interrogated for diet, diabetes and interaction effect using ANOVA with significance set at p≤0.05.

Results

HF diet‐exposed cardiomyocytes demonstrated abnormal cardiac bioenergetics profiles, increased lipid peroxidation, and a relatively decreased ability to recover from FCCP challenge with signs of mitochondrial dysfunction on live cell imaging. Combination‐exposed cardiomyocytes were most severely affected.

Conclusion

Late gestation diabetes alters cardiac metabolism in the developing heart and the effects are exacerbated with prenatal exposure to a maternal HF diet. These cardiometabolic consequences persist into adulthood. The FCCP challenge demonstrates that combination exposed offspring have an impaired ability to maintain ATP production under stress which is a significant risk factor for heart disease. Together, our findings highlight that cardiac metabolism plays a significant role in developmentally programmed cardiovascular disease in offspring of diabetic pregnancy.

Support or Funding Information

NIH‐NICHD K08HD078504, Sanford Research, SSOM‐USD Faculty Grant, Sanford Health– SDSU Collaborative Research Seed Grant, Institutional Development Awards (IDeA) NIH ‐GMS P20GM103620‐01A1 (Pediatrics) and P20GM103548 (Cancer) COBRE grants
Elementary TRPV4 sparklets in the endothelium dilate mouse pulmonary arteries
Authors: Marziano Corina , Hong Kwangseok , Cope Eric L , Sonkusare Swapnil K
Published: November 2023

Endothelial dysfunction is a hallmark of pulmonary disorders including pulmonary hypertension, pulmonary edema, acute lung injury and ischemia. Ca2+ influx through TRPV4 (transient receptor potential vanilloid 4) channels plays an important role in regulating the function of pulmonary endothelium, and abnormal TRPV4 channel activity has been associated with lung injury, ischemia, and pulmonary edema. However, the function of TRPV4 channels and their regulation by physiological stimuli in the pulmonary endothelium remain unknown. The objectives of this study were to elucidate the regulation of TRPV4 channels in pulmonary endothelium under physiological conditions; and to identify the Ca2+‐sensitive targets that mediate TRPV4‐induced vasodilation in these arteries. Third or higher order pulmonary arteries (PAs) were isolated, slit‐open and pinned down, and the Ca2+ signals were recorded using a spinning disk confocal imaging system. In the presence of cyclopiazonic acid to deplete the internal stores of Ca2+, TRPV4 channel function was recorded as Ca2+ influx events‐TRPV4 sparklets (Sonkusare et al., Science, 2012). The activity of TRPV4 sparklets, estimated as fluorescence integral over a field of view, was increased by 3‐ and 17‐fold in the presence of 3 and 10 nM GSK1016790A (TRPV4 agonist), respectively, when compared to the baseline. The TRPV4 sparklets were inhibited by TRPV4 channel inhibitor HC067047 (1 μM); and were absent in the presence of 0 mM extracellular Ca2+ in both the endothelium‐denuded arteries and the arteries from TRPV4 knockout mice. A multi‐Gaussian curve fit to the all‐points histogram of the fractional fluorescence traces revealed a single channel amplitude of 0.18 ΔF/F0 in the mice that express Ca2+ biosensor GCaMP2 selectively in the endothelium, and 0.28 ΔF/F0 in the arteries loaded with fluo‐4AM. The TRPV4 sparklet amplitudes were not affected by a change in the agonist concentration, or in the presence of TRPV4 inhibitor. The effect of TRPV4 channel activation on arterial diameter was studied in the PAs cannulated and pressurized to 10–20 mm Hg and pre‐constricted with U46619 (50–100 nM). GSK101 (30 nM) induced a 67% vasodilation which was mostly inhibited by NG‐nitro‐L‐Arginine (nitric oxide synthase (NOS) inhibitor, 100 μM). Our results support the concept that TRPV4 sparklets in PA endothelium represent single TRPV4 channel openings that cause vasodilation via NOS activation. These results will enable direct studies of TRPV4 channel regulation in PAs under healthy and diseased conditions.

Support or Funding Information

Supported by NIH award HL121484 to SKS