bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basal Endothelial Cell Autophagy is Elevated in Trained vs. Sedentary Mice
Authors: Cho Jaemin , Kim Ji‐Seok , Allsop Jeff , Bean Tyler , Bonn Trevor , Hestwood Gabby , Yang Kevin , Drummond Micah , Babu Pon Velayutham Anandh , Symons J David 
Published: November 2023

Autophagy is a process whereby damaged cellular cargo is delivered to the lysosome for degradation and eventual recycling or removal. A reduction of autophagy‐related (Atg) mRNA and protein expression in endothelial cells (ECs) from old rodents and humans is associated with arterial dysfunction. One study reports increased indices of autophagy in aortae from trained vs. sedentary rats (Sun et al., Cardiovascular Res, 2013), but the cellular subtypes were not evaluated. Exercise‐training could improve vascular health by upregulating EC autophagy. We hypothesized that exercise‐training increases basal EC autophagy. Five‐month old male C57Bl6 mice were treadmill‐trained (ETR, n=6, 32±1 g) or remained sedentary (SED, n=5, 32±1 g) 6 days per week. After 10‐weeks, total workload performed during a maximal exercise test was greater (p<0.05) in ETR (3.63±0.48 kgm) vs. SED animals (1.08± 0.22 kgm). 24 hours following the total workload test, soleus muscle, iliac artery, carotid artery, and aorta were obtained. The respiratory control ratio (RCR, state III to state IV respiration) was greater (p<0.05) in soleus from ETR (2.04±0.14) vs. SED mice (1.31±0.16). Citrate synthase activity (μmol/min/g) was greater (p<0.05) in soleus from ETR (0.99 ± 0.07) vs. SED (0.54 ± 0.14) mice. These findings verify the efficacy of our training protocol. ECs and media + adventitia (M+A) were obtained from the iliac and carotid arteries. mRNA expression was quantified by real‐time RT‐PCR using SYBR green fluorescence. Cycle threshold (Ct) values were normalized to the housekeeping gene 18S. Purity of the EC and M+A fractions obtained from carotid and iliac artery was confirmed by measuring PECAM‐1 and α‐SMA expression respectively. mRNA expression increased 1.8 – 4.1‐fold (p<0.05) for beclin‐1, LC3‐II, Atg3, Atg5, Atg7, Atg12, and Atg16 in iliac artery ECs, but not carotid artery ECs, from ETR vs. SED mice. All of these autophagy‐related genes in the M+A from iliac and carotid artery were similar in ETR and SED mice. LC3II:GAPDH and Atg3:GAPDH protein expression was greater (p<0.05) in aortic homogenates from ETR vs. SED mice. Collectively, exercise‐training increases the expression of autophagy‐related mRNA in iliac artery ECs, and autophagy‐related protein in arterial homogenates, relative to results obtained from sedentary animals. Ongoing experiments are determining whether exercise‐training increases basal expression of autophagy‐related mRNA and protein in the vasculature of old mice to an extent that attenuates age‐related arterial dysfunction.Support or Funding InformationSupported by: UU Diabetes and Metabolism Center; UU Center on Aging; UU College of Health Research Committee; DRC at Washington University (5 P30 DK020579); and AHA 16GRNT31050004 (JDS).
Combined Norepinephrine and ATP Antagonism Attenuates the Vasoconstriction Response in Young Adult Skin
Authors: Krajek Alex C , Smaller Kevin A , Lang James A 
Published: November 2023

Norepinephrine (NE) is responsible for ~60% of the vasoconstriction (VC) response to cold exposure in young adults whereas the remainder is due to unknown coreleased sympathetic adrenergic neurotransmitter(s). We hypothesize that ATP is a cotransmitter and thus, combined ATP and NE antagonism will further inhibit the reflex cutaneous VC response. Two protocols were conducted in young adults; both involved the placement of three microdialysis (MD) fibers in forearm skin and whole‐body cooling (Tsk = 30.5 °C). Protocol 1 infused 1) lactated Ringer's solution (control), 2) 10mM L‐NAME, and 3) purinergic receptor blockade with 1mM suramin + L‐NAME. Protocol 2 infused 1) Ringer's, 2) suramin + L‐NAME, and 3) suramin + L‐NAME + adrenoreceptor blockade with 5mM yohimbine + 1mM propranolol. Laser Doppler flux (LDF) was measured over each MD site and cutaneous vascular conductance (CVC) was calculated as CVC = LDF/MAP and expressed as percent changes from baseline (%ΔCVC). L‐NAME was used to block the vasodilatory influence of ATP and unmask the P2X‐mediated VC response to exogenous ATP infusion (−21 ± 2 %ΔCVC). During whole body cooling, the VC response (control: −39 ± 3 %ΔCVC) was attenuated in the suramin site (−21 ± 2 %ΔCVC) and further blunted with combined adrenoreceptor blockade (9 ± 1 %ΔCVC; p < 0.05). Compared to control (22 ± 1 %ΔCVC), suramin inhibited pharmacologically‐induced VC to tyramine (12 ± 2 %ΔCVC), which acts to displace adrenergic neurotransmitters from axon terminals. Collectively, these data indicate that ATP contributes to the cutaneous adrenergic VC response in humans.Support or Funding InformationFunded by Iowa Osteopathic & Education Research Grant (IOER #03‐14‐01)
Intermittent Hypoxic Challenge in Conscious Rats Elevates Heart Rate But Does Not Increase Lumbar Sympathetic Nerve Activity
Authors: Muntzel Martin , Loera Jaclquelin , Coffee Gregory , Getsy Paulina , Lewis Stephen J 
Published: November 2023

In humans, moderate duration hypoxia (20 min) stimulates well‐described increases in muscle sympathetic nerve activity (SNA) that persist after withdrawal of the hypoxic challenge. However, episodes of naturally occurring apnea in humans and animals are of shorter duration, and the effects of such brief exposures to hypoxia on SNA have been little studied. To test this, male Sprague‐Dawley rats were instrumented with radiotelemetry devices to record mean arterial pressure (MAP), heart rate (HR) and lumbar SNA. After 3 days of recovery from surgery, the animals were exposed to four consecutive episodes of hypoxia (10% O2, 90% N2), that were 5 min in duration and given 10 min apart, all while recording cardiovascular and ventilatory responses. In ongoing studies, we found that the repeated hypoxic episodes produced expected increases in tidal volume, breathing frequency, and minute veltilation. Hypoxia also activated increases in HR (+57 ± 21 bpm) accompanied by mild elevations in MAP (+6 ± 5 mmHg). Unexpectedly, the hypoxic challenges caused no change in lumbar SNA (from 100% to 106 ± 14%), and did not increase SNA following offset of the challenges. At study end, a testing of lumbar SNA quality revealed that the nerves responded appropriately to sodium nitroprusside, phenylephrine and to hexamethonium bromide. These data show that repeated short‐term hypoxic challenges did not did not elevate lumbar SNA in conscious rats.Support or Funding InformationGalaxoSmithKline Pharmaceuticals
The Effect of Methylglyoxal (MGO) on the Cardiac Myofilament
Authors: Papadaki Maria , Holewinski Ronald , Stachowski Marisa , Kirk Jonathan 
Published: November 2023

Methylglyoxal (MGO), a byproduct of glycolysis and a reactive carbonyl species (RCS), is significantly elevated in diabetes. MGO adds post‐translational modifications by reacting with arginine and lysine residues to form irreversible carbonyl adducts. At basal concentrations, MGO is removed by glyoxal‐1 (GLO‐1), but at concentrations observed in diabetes, GLO‐1 cannot meet the demands and MGO modifications can accumulate. In the heart, MGO has been previously found to act on the ryanodine receptor and SERCA to depress calcium transients, and other proteins to induce cardiomyocyte apoptosis. However, the effect of MGO on the cardiac myofilament has never been studied. The aim of this study is to characterize the structural and functional effects of MGO on the myofilament. Skinned myocytes were isolated from ~100 μg of mouse left ventricle heart tissue, skinned using 0.3% Triton for 20 minutes and force‐Ca2+ relationships were measured. 20 minute exposure to 100 μM MGO reduced the myocyte maximal calcium activated force (Fmax) by 12 ± 4 % (n = 8, p = 0.048) and Ca2+ sensitivity by 45 ± 11 % (n = 8, p = 0.02). With 10 μM MGO, Ca2+ sensitivity was decreased by 67 ± 17 % (n = 9, p<0.01) but there was no effect on Fmax. Using mass spectrometry, we identified MGO modifications on several myofilament proteins in mouse myocytes treated with MGO including actin, myosin and myosin essential light chain. In a pilot study, using immunoprecipitation assay we were able to detect similar MGO modifications on myofilament proteins from human diabetic cardiomyopathy tissue that were not present in control hearts (n = 2/group). Our data show that these modifications would have significant implications on myofilament function in patients suffering from diabetic cardiomyopathy and other diseases affecting glucose metabolism.Support or Funding InformationThis project is supported by American Heart Association
Cholesterol Depletion Increased Cardiomyocyte Contractility Associated with Phosphorylation of Cytosolic AKT
Authors: Haque Mohammed Ziaul , McIntosh Victoria J. , Mohammad Ramzi M , Samra Abdul Badi Abou , Lasley Robert D 
Published: November 2023

IntroductionSarcolemmal cholesterol is concentrated in lipid rafts and caveolae, which are flask‐shaped invaginations of the plasma membrane and plays an important role for cell function. In cardiomyocyte the scaffolding protein caveolin‐3 permits the enrichment of cholesterol in caveolae, and caveolin‐3 interactions with numerous proteins regulate their function.HypothesisWe hypothesized that acute cholesterol depletion increases cardiomyocyte intracellular Ca2+ and contractility.MethodsVentricular myocytes, isolated from adult Sprague Dawley rats, were treated with the cholesterol reducing agent methyl‐β‐cyclodextrin (MβCD, 5 mM, 1 hr, room temperature). Total cellular cholesterol levels, caveolin‐3 localization, subcellular, AKT, ERK and p38 signaling, [Ca2+]i and contractility were assessed.ResultsTreatment with MβCD reduced ~45% cholesterol and shifted caveolin‐3 from cytoskeleton and triton‐insoluble fractions to the triton‐soluble fraction. Cholesterol depletion increased 2.4‐fold AKT phosphorylation only in cytosolic fraction, an effect that was independent of total cytosolic AKT. Cholesterol depletion increased ERK isoform phosphorylation in cytoskeletal, cytosolic, triton‐soluble and triton‐insoluble membrane fractions without altering their subcellular distributions. The primary effect of MβCD was on p38 subcellular distribution of p38α with little effect on p38 phosphorylation. Cholesterol depletion increased cardiomyocyte twitch amplitude and the rates of shortening and relaxation in conjunction with increased diastolic and systolic [Ca2+]i.ConclusionThese results indicate that acute reductions in membrane cholesterol levels modulates subcellular caveolin‐3, AKT, ERK, p38 signaling, as well as increasing [Ca2+]i and contractility.Support or Funding InformationThis work was supported by National Heart, Lung, and Blood Institute, Grants HL‐66132 to RDL.
Time‐Released Caffeine Ingestion in Habitual Users May Extend Parasympathetic Influence as Determined by Heart Rate Variability
Authors: La Monica Michael B , Fukuda David H , Gonzalez Adam M , Wang Ran , Wells Adam J , Stout Jeffrey R , Hoffman Jay R 
Published: November 2023

Heart rate variability (HRV) is a noninvasive method of identifying vagal and sympathetic control of heart rate via time‐domain and frequency‐domain measures. Caffeine has shown to enhance autonomic responsiveness by increasing parasympathetic influence, however a time‐release caffeine supplement has not yet been investigated.OBJECTIVETo determine the effects of a time‐release caffeine supplement on HRV over 8 hours.METHODSTen men (25.9 ± 3.2 y; 1.81 ± 0.08 m; 92.9 ± 9.9 kg), who were habitual caffeine users (>200mg/day), volunteered to participate in an acute randomized, double‐blind, placebo‐controlled study. Participants performed three trials with seven days between each trial. During each trial, participants randomly consumed either 194 mg of caffeine in a multi‐ingredient supplement containing time‐release caffeine (TR‐CAF); a regular caffeine supplement (CAF); or a placebo (PL). Participants reported to the lab at 0800 hour following an 8‐hour fast and having abstained from caffeine. HRV was assessed for 10 min via Polar heart rate monitor with the participant lying in the supine position during baseline, before supplementation, and each hour during each 8 hour trial. Time‐domain [mean standard deviation of all normal‐to‐normal (NN) intervals (SDNN in ms), root mean square of differences between adjacent NN intervals (RMSSD in ms), the number of pairs of adjacent NN intervals differing by more than 50 ms within the entire recording (NN50), the proportion of NN50 count relative to the total number of all NN intervals (pNN50)] and frequency‐domain [low frequency (LF in ms2), high frequency (HF in ms2), total power (in ms2), LF/HF, an index of parasympathetic nervous system (PNS=HF/total power) measures were recorded. A two‐way [trial (CAF vs. TR‐CAF vs. PL) × time (BL, 1hr, 2hr, 3hr, 4hr, 5hr, 6hr, 7hr, 8hr)] RMANOVA was used to assess all HRV parameters.RESULTSA significant interaction was noted for PNS (p = .045). Post‐hoc analyses revealed elevations in PNS influence occurred in both TR‐CAF (0.27 ± 0.12, p = .045) and CAF (0.29 ± 0.16, p = .009) compared to PL (0.18 ± 0.08) at hour 6 and hour 7 in TR‐CAF (0.34 ± 0.15, p = .018) compared to PL (0.23 ± 0.13). There were significant main effects of time for RMSSD (p = .021) and pNN50 (p = .012).DISCUSSIONBoth caffeine supplements increased parasympathetic influences within the autonomic nervous system over an 8‐hour span. However, the time‐release caffeine supplement appeared to have a slightly longer lasting effect on parasympathetic influence than regular caffeine. Overall, caffeine in the concentrations ingested in this study increases vagal stimulation, but has no effect on other elements of HRV in habitual caffeine users.
Acute Changes in Left Ventricular Mechanics During Voluntary Apnea
Authors: Sutterfield Shelbi L , Smith Joshua R , Baumfalk Dryden R , Didier Kaylin D , Ade Carl J 
Published: November 2023

IntroductionObstructive sleep apnea (OSA) is characterized by intermittent apneic events and is associated with hypertension, sudden cardiac death, and acute cardiac infarction. During an apneic event asphyxia‐induced increases in sympathetic nerve activity result in subsequent increases in arterial blood pressure and systemic vascular resistance. However, it is currently unknown how cardiac mechanics are acutely impacted by these systemic responses to an apneic event. Therefore, the purpose of the present study was to evaluate changes in left ventricular systolic and diastolic function during voluntary apnea. We hypothesized that during voluntary apnea left ventricular systolic and diastolic function would be compromised in parallel with increases in arterial blood pressure and myocardial work.Methods9 healthy men (23 ± 3 yrs) were recruited for the study. Subjects performed multiple voluntary breath holds at functional residual capacity with 3–5 minutes in between. Beat‐by‐beat blood pressure, heart rate and stroke volume were measured continuously. End‐tidal CO2 was measured at end‐apnea. Tissue Doppler echocardiography was used to measure tissue velocities, and myocardial deformation via strain (S), and strain rate (SR) at the mid‐interventricular septum across 3 continuous cardiac cycles at baseline and end‐apnea.ResultsSystolic blood pressure (Δ13.8 ± 8.4 mmHg, p<0.01), mean arterial pressure (Δ12.4 ± 7.0 mmHg, p<0.01), and rate pressure product (Δ8.4 ± 5.6 mmHg × bpm 10−2, p<0.01) significantly increased with apnea, but not stroke volume (Δ3.3 ± 8.1 ml, p=0.26). Peak longitudinal systolic (Δ −0.56 ± 0.69 cm s−1, p=0.04) and early LV filling (Δ −2.32 ± 2.04 cm s−1, p<0.01) myocardial velocities were significantly decreased during the apnea. Longitudinal Systolic S (Δ −2.17 ± 2.36%, p=0.02) and SR (Δ −0.20 ± 0.29 1/s, p=0.07) were significantly decreased during the apnea. Early LV filling SR was not different compared to baseline with apnea (p=0.41).ConclusionConsistent with our hypotheses, left ventricular deformation was significantly impaired with voluntary apnea. These data suggest that the systemic increases in arterial pressure during voluntary apnea have an adverse effect on left ventricular systolic mechanics.
Protective Effects of mTOR Against Ferroptosis, a Form of Iron‐dependent Regulated Cell Death, in Cardiomyocytes
Authors: Baba Yuichi , Shimada Briana K , Horiuchi Kate M , Higa Jason K , Matsui Takashi 
Published: November 2023

While iron is important for maintaining physiological metabolism, excess iron causes tissue damage in multiple organs, including the heart. Ferroptosis was recently reported as a new form of iron‐dependent necrosis. Although ferroptosis is a key etiological factor in cancer and other human diseases, the role of ferroptosis in the heart is less understood. Previous studies from our group and others demonstrated that the mechanistic target of rapamycin (mTOR) is sufficient and necessary to prevent cardiomyocyte (CM) cell death induced by pathological stresses, including ischemia and pressure overload. To define the role of mTOR on ferroptosis‐mediated cell death in CMs, we treated mouse adult CMs with erastin, a ferroptosis inducer, and examined whether mTOR overexpression prevents ferroptosis‐mediated cell death in CMs. Mouse adult CMs were isolated from hearts of either male transgenic mice with cardiac‐specific overexpression of mTOR (mTOR‐Tg) or littermate negative (WT) mice at 12–20 weeks of age, and cultured in conditioned medium (Medium 199, 100 μg/ml bovine serum albumin, insulin‐transferrin‐sodium selenite, 25 μM blebbistatin, 100 U/ml penicillin, 100 μg/ml streptomycin). One day after plating, CMs were treated with erastin or DMSO vehicle. Cell viability was assessed by Live/Dead Cell Viability Assay (2 μM calcein AM for survival, and 4 μM ethidium homodimer‐1 for cell death). Treatment with excess iron [1 mM iron (III) citrate] induced 4.4‐fold higher cell death in WT cells compared to vehicle controls (p<0.01, n=6). Sixteen‐hour treatment with 40 μM erastin induced significant cell death (control 18.1±0.7% vs. erastin 32.0±0.5%, p<0.01, n=4), and co‐treatment with 5 μM of ferrostatin‐1, a ferroptosis inhibitor, attenuated erastin‐induced cell death (p<0.05, n=4). Intriguingly, the number of dead cells induced by erastin was significantly lower in CMs isolated from mTOR‐Tg mice compared to that from WT mice (p<0.05, n≥4). Ferroptosis is also mediated by an increase in reactive oxygen species (ROS) generation. We measured ROS production with 25 μM 2′,7′dichlorofluorescein acetate (DCFDA). Erastin‐induced ROS production was ~50% lower in mTOR‐Tg than WT. These findings suggest that another form of regulated cell death, ferroptosis, occurs in CMs, and that overexpression of mTOR inhibits ferroptosis at least in part by attenuating ROS production. Understanding mechanisms of ferroptosis in CMs will provide a novel therapeutic strategy for many cardiac diseases such as heart failure, in which preventing CM cell death plays an important role in preserving cardiac function.Support or Funding InformationThis work was supported in part by grants from the NIH (P30GM103341) to TM and Kochi Organization for Medical Reformation and Renewal to YB.
Intravenous Delivery of Cardiosphere‐Derived Cells Improves Striated Muscle Function and Structure in a Murine Model of Duchenne Muscular Dystrophy
Authors: Rogers Russell G , Aminzadeh Mark A , Fournier Mario , Gouin Kenneth , Sanchez Lizbeth , Li Liang , Sakoda Chris , Marban Eduardo 
Published: November 2023

Duchenne muscular dystrophy (DMD), the most common inherited muscular disease, affects approximately 1 in 3,500 live‐born males worldwide. Loss of dystrophin results in a myriad of dysfunctional cellular processes that ultimately manifest as severe and progressive muscle‐wasting in both cardiac and skeletal muscle. DMD patients are clinically characterized by an early loss of ambulation followed by dilated cardiomyopathy in the second decade of life. There is no cure for DMD and current treatments marginally slow the progression of the disease course. Cardiosphere‐derived cells (CDCs) are cardiac progenitor/stromal cells with regenerative, angiogenic, anti‐inflammatory, and anti‐fibrotic properties. Previous research has demonstrated that CDCs are efficacious in treating both ischemic and non‐ischemic heart disease, including Duchenne cardiomyopathy in mdx mice – a mouse model of DMD. The latter work motivated the ongoing HOPE‐Duchenne clinical trial to treat DMD‐associated cardiomyopathy. Here, we sought to explore the potential of CDCs to treat both cardiac and skeletal myopathies when delivered systemically. A single bolus of syngeneic CDCs or vehicle were administered via the femoral vein of 10‐month‐old mdx mice. Baseline and three week follow up measurements of ambulatory capacity, in vivo cardiac function, and isolated skeletal muscle function were recorded. Systemic delivery of CDCs partially reversed the dystrophic phenotype in the heart and skeletal muscle of mdx mice. Specifically, CDC treated mice ran 34.6% (p = 0.01) farther than vehicle‐treated mice. Moreover, CDC treatment improved cardiac ejection fraction by 18.7% (p = 0.008) and isometric force developed by the soleus muscle by 47.8% (p < 0.001), to levels comparable to those in age‐matched wild type controls. Histological examination of the hearts and solei revealed fewer necrotic lesions in CDC treated mice. Interestingly, solei from CDC treated mice contained more centrally nucleated myofibers (208.7 ± 20.7 vs 106.8 ± 9.0, p = 0.004), consistent with enhanced active regeneration. Further, immunohistological staining of the soleus demonstrated that CDC treatment promoted nascent myotube formation, indicating replenishment of a pool of fusion‐competent myoblasts. These data demonstrate that a single intravenous infusion of syngeneic CDCs is sufficient to impact favorably on the phenotype of the mdx mouse. Given that CDCs are already in advanced clinical testing, the present work motivates clinical testing of CDCs delivered systemically to DMD patients, looking for improvements in cardiac and skeletal muscle function and biomarkers.Support or Funding InformationNIH T32 HL116273
GPCR signaling in brown/beige adipose tissue (Symposium: Adipose Tissue and the Cardiovascular System: Interactions with Sleep and Cardiometabolic Risk Factors)
Authors: Pfeifer Alexander 
Published: November 2023

Overweight and obesity are associated with a high risk for cardiovascular disease, diabetes and certain tumors. Sleep disorders have been linked to obesity in multiple way: on one hand obesity increases the risk for obstructive sleep apnea on the other hand sleep disorders are associated with obesity. Brown adipose tissue (BAT) is a special type of fat that dissipates energy to produce heat. In human adults, BAT activity inversely correlates with body‐mass index and is therefore considered as a possible target for treatment of overweight and obesity. Moreover, brown‐fat like cells have been described in white fat depots; these cells are also knonw as brite (brown‐in‐white) or beige cells and their number and activity can be induced by cold exposure and pharmacological stimulation in a process described as ‘browning’.G protein‐coupled receptors (GPCRs) regulate a variety of cellular functions. Importantly, Gs‐coupled GPCRs activate BAT energy expenditure. Our aim is to identify the GPCRs involved in BAT activation and/or recruitment. To this end, we profiled the GPCR expression profile in preadipocytes and mature brown adipocytes. Unexpectedly, we found that a major part of GPCRs in brown adipocytes.Using a variety of pharmacological and genetic tools, we found that Gq‐coupled receptors inhibit brown and beige adipocyte differentiation. Further studies revealed that that Gq signaling is linked to RhoA/ROCK signaling in these cells.Taken together, Gq signaling is an important regulator of brown adipocyte differentiation.Support or Funding InformationFunding: DFG