bluuebunny/crossref_metadata_2025_split huggingface dataset:
Verapamil But Not Lidocaine Suppresses Ischemia‐Induced Ventricular Fibrillation in The Isolated Female Rat Heart
Authors: Davitt Katlin , Hensley Lauren , Clements‐Jewery Hugh 
Published: November 2023

Background and GoalsVentricular fibrillation (VF) triggered by myocardial ischemia is believed to account for the majority of sudden cardiac death, which is responsible for over 300,000 deaths annually in the United States, indicating the need for effective and safe pharmacological therapeutic prevention. Historically, animal models used to identify antiarrhythmic drugs have excluded female models of ischemia‐induced VF, raising the possibility that the paucity of effective and safe antiarrhythmic drugs available clinically is in part due to drugs lacking efficacy in females. In the present study we evaluated in isolated female rat hearts the antiarrhythmic efficacy of verapamil and lidocaine at concentrations that are known to be antiarrhythmic in male rat hearts.MethodsHearts were isolated from male and female rats and perfused in the Langendorff mode with modified Krebs solution containing 3mM K+. Six different treatment groups were used (n=12–13 per group). There were corresponding separate male and female groups: control (vehicle ‐ water); verapamil (300nM) and lidocaine (12.93μM). After a 5 min baseline perfusion period the solution was switched in a randomized and blinded manner to one of the test solutions. After a further 15 minutes, regional ischemia was induced by left main coronary ligation and maintained for 30 min. The ECG was used to identify the occurrence of VF and other arrhythmias during ischemia as well as for the measurement of electrocardiographic intervals. An intraventricular balloon was used to record left ventricular developed pressure (LVDP) and end diastolic pressure. Coronary flow was recorded digitally using the calibrated signal from a pump controller.ResultsVerapamil and lidocaine produced near identical hemodynamic effects in male and female hearts consistent with their established mechanisms of action. Compared to control hearts, verapamil decreased LVDP but increased coronary flow whereas lidocaine decreased both heart rate and coronary flow. The VF incidence was 54% and 45% in control male and female hearts respectively, which was lower than that observed in previous studies from our laboratory. The incidence of VF in the presence of verapamil was similar in male and female hearts (17% & 8% respectively) but lidocaine suppressed VF in male hearts only (8% VF vs 46% VF in females).ConclusionsAt concentrations that are antiarrhythmic in male rat hearts, verapamil but not lidocaine suppressed VF in female rat hearts. Further investigation is merited.Support or Funding InformationSupported by an intramural grant from the West Virginia School of Osteopathic Medicine.
Influence of Carotid Chemoreceptors on Cerebral Blood Flow during Normoxic Conditions
Authors: Malterer Katherine R. , Holbein Walter W. , Harvey Ronee E. , Johnson Blair D. , Joyner Michael J. 
Published: November 2023

BackgroundEvidence indicates that the carotid chemoreceptors play a minimal role in regulating cerebral blood flow under normoxic resting conditions. However, studies in heart failure suggest over‐active carotid chemoreceptors may decrease cerebral blood flow. With this information in mind, we hypothesized that individuals with the highest resting chemosensitivity will have the greatest increase in cerebral blood flow when the carotid chemoreceptors are desensitized with low‐dose IV dopamine.MethodsSeven young, healthy men (33±3 y) participated in two randomized, double‐blinded study days separated by at least 4 weeks. Middle cerebral artery blood velocity (MCAv, transcranial Doppler) was measured continuously as a surrogate for cerebral blood flow. Cerebral vascular conductance index (CVCi) was calculated by normalizing MCAv for blood pressure as measured by brachial arterial catheter (MCAv/mean arterial blood pressure) and blood gasses were drawn. Subjects rested quietly in the supine position for 5‐minutes during intravenous saline infusion (saline and dopamine baseline). This was followed by a 25‐minute continuous IV infusion of either saline or dopamine. The dose of dopamine was individualized (1–2 μg/kg/min) such that it resulted in a nadir hypoxic ventilatory response. Data were analyzed from the last 5‐minutes of the infusion period (saline infusion or dopamine infusion) and compared to baseline data.ResultsSaline and dopamine infusion did not affect mean arterial blood pressure (% change saline vs dopamine day: 1.3±1.2 vs 0.9±1.3%; p>0.05) or arterial blood CO2 (% change saline vs dopamine day: −2.6±1.7 vs 1.6±1.9%; p>0.05). Dopamine infusion resulted in a significant reduction in carotid body chemosensitivity as assessed by the hypoxic ventilatory response (dopamine baseline vs infusion HVR: 0.33±0.06 vs 0.17±0.03 L/min/%SpO2; p=0.027). No changes in MCAv or CVCi were observed with saline infusion (saline baseline vs infusion: p>0.05). Dopamine did not alter MCAv (dopamine baseline vs infusion: 62±5 vs 64±5 cm/s; p>0.05). Similarly, no changes in CVCi were observed with dopamine infusion (dopamine baseline vs infusion: 0.68±0.07 vs 0.68±0.06 cm/s/mmHg; p>0.05). Although differences in group means for MCAv and CVCi were not observed with dopamine infusion, a significant negative relationship was found between baseline carotid chemosensitivity and the change in MCAv (r2=0.594, p=0.043), and CVCi (r2=0.741, p=0.013). With saline infusion, no significant relationship was found between baseline carotid chemosensitivity and the change in MCAv (r2=0.091, p>0.05), and CVCi (r2=0.089, p>0.05).ConclusionsBlunting of the carotid chemoreceptors using IV dopamine has no group effect on MCAv or CVCi. However, contrary to our hypothesis, individuals with highest resting chemosensitivity had either a decrease or no change in cerebral blood flow after carotid body desensitization.Support or Funding InformationW81XWH‐13‐2‐003
Connexin hemichannels and pannexin channels contributes to the intracellular Ca2+ signal activated by PAF in endothelial cells of mesenteric post‐capillary venules
Authors: Burboa Pia C , Poblete Ines , Figueroa Xavier 
Published: November 2023

Endothelial cells form a permeability barrier to macromolecules that can be modulated in post‐capillary venules through the activation of Ca2+‐dependent signaling pathways by pro‐inflammatory agents, such as platelet‐activating factor (PAF). This Ca2+ signaling depends on Ca2+ release from the endoplasmic reticulum and Ca2+ influx from the extracellular space, in which may be involved membrane channels formed by connexins (i.e. hemichannels) or pannexins. We analyzed the participation of these channels in the PAF‐elicited intracellular Ca2+ concentration ([Ca2+]i) increase. To this end, we used the intact mesenteric vascular bed and primary cultures of mesenteric endothelial cells (EC) of resistance arteries (EC‐A) and venules (EC‐V). Changes in [Ca2+]i were recorded using the fluorescent Ca2+ indicator Fluo‐4 and activity of connexin hemichannels or pannexin channels was evaluated by assessing ethidium uptake in EC and intact vessels. As expected, 1 μM acetylcholine induced an increase of [Ca2+]i in EC‐A, but not in EC‐V and, in contrast, 10 nM PAF evoked a response only in EC‐V. ATP (5 μM) activated a Ca2+ response in both EC‐A and EC‐V. In addition to activate a Ca2+ signal in EC‐V, PAF also induced an increase in ethidium uptake in these cells and in venules of intact mesenteric bed, without affecting the ethidium signal in mesenteric arteries. Treatment for 15 min with the connexin blocking peptide 37, 43Gap27 or the pannexin‐1 blocking peptide 10Panx abolished the increase in [Ca2+]i and ethidium uptake induced by PAF, suggesting that connexin hemichannels and pannexin‐1 channels contribute to the PAF‐activated Ca2+ signal. Cx37, Cx40, Cx43 and pannexin‐1 were found to be expressed in intact venules, intact resistance arteries and in EC‐V and EC‐A by immunofluorescence analysis and western blot. Connexin and pannexin channels are permeable to Ca2+, but they may also trigger Ca2+ signals through ATP release and, consistent with this, blockade of purinergic receptors with PPADS blunted the PAF‐induced [Ca2+]i increase. These results suggest that the intracellular Ca2+ signaling activated by PAF in endothelial cells of post‐capillary venules is mainly mediated by ATP release through connexin hemichannels and/or pannexin‐1 channels, which, in turn, leads to activation of purinergic receptors. However, direct Ca2+ influx via connexin hemichannels or pannexin‐1 channels may also contribute to the responseSupport or Funding InformationFONDECYT 1150530
Dual and Divergent Location‐Specific Functions of Active Caspase 3 are Regulated by MK2
Authors: Damarla Mahendra , Carino Kathleen , Suresh Karthik , Johnston Laura , Kim Bo , Kolb Todd , Damico Rachel , Machamer Carolyn , Shimoda Larissa , Hassoun Paul 
Published: November 2023

BackgroundWe have previously shown that MK2 deficiency leads to cytoplasmic sequestration of active caspase 3, prevention of apoptosis and is associated with a preserved endothelial barrier function in response to endotoxin challenge. While caspase 3 is widely described as the executioner of apoptosis, it has numerous cytosolic substrates that are not related to execution of apoptosis. Therefore, we hypothesized that cytosolic caspase 3 promotes endothelial barrier function and MK2 converts caspase 3's barrier protective function to apoptosis‐promoting thereby stimulating pulmonary vascular permeability.MethodsHuman lung micro‐vascular endothelial cells (HMVECs) were exposed to a non‐apoptotic, thrombin, or an apoptotic, lipopolysaccharide (LPS), stimulus and endothelial barrier function was assessed using electric cell‐substrate impedance sensing (ECIS). After exposures, a subset of HMVECs were evaluated for actin cytoskeletal rearrangement using phalloidin staining. In addition, HMVEC cell lysates were harvested for protein analyses. Caspase inhibition was achieved using the pharmacological inhibitor q‐VD‐OPH.ResultsExposure of HMVECs to LPS led to an initial enhancement of endothelial barrier integrity as measured by an increase in electrical resistance, followed by pronounced endothelial barrier disruption which did not recover. Intriguingly, the LPS‐induced transition from barrier enhancement to endothelial barrier disruption is associated with nuclear translocation of active caspase 3 and subsequent apoptosis. Knockdown of MK2 prevented LPS‐induced nuclear translocation of caspase 3 and apoptosis. In response to thrombin, HMVECs demonstrate a dose dependent transient decrease in endothelial barrier function as measured by a drop in electrical resistance followed by a rapid recovery on ECIS. Inhibition of caspases in HMVECs led to a similar drop in thrombin‐induced endothelial barrier function but notably there was no subsequent barrier recovery; lack of barrier recovery was not a result of endothelial cell death. Interestingly, LPS but not thrombin leads to MK2 activation.ConclusionTaken together, our results suggest that MK2 phosphorylates caspase 3 leading to its nuclear translocation, subsequent apoptosis and barrier disruption; whereas unphosphorylated active caspase 3 remains cytosolic and promotes endothelial barrier integrity.Support or Funding InformationNIH‐ NHLBI
Smooth Muscle Cell and Endothelial Cell Expression Profiles for Membrane Receptors: Effects of Aging and Vessel Type
Authors: Boerman Erika M , Shaw Rebecca , Ramnath Anjana , Joshi Trupti , Segal Steven S 
Published: November 2023

Smooth muscle cells (SMCs) and endothelial cells (ECs) interact to control dilation and constriction of resistance arteries, thereby regulating tissue blood flow and oxygen delivery. The functions of and interactions between SMCs and ECs are regulated by multiple membrane receptors and ion channels. While the expression of genes encoding these proteins varies between cell types, how such expression is affected by aging and may vary between vascular beds are poorly understood. To probe these relationships, we applied genomics and informatics to test the hypothesis that the expression profile of membrane receptors mediating vascular reactivity to physiological agonists varies not only with cell type, but is affected by biological age and vessel type. Individual mesenteric artery (MA) and superior epigastric artery (SEA) segments were collected from Old (24–26 months) and Young (3–6 months) male C57BL/6 mice; each vessel was dissociated to obtain ~5,000 EC and 500 SMCs (n=5 per group). Total RNA was extracted from each cell sample; custom Taqman qRT‐PCR arrays were used to determine the expression profile of receptors. Critical threshold (ΔΔCT) values were generated and t‐tests computed for identifying significant changes at P<0.05. Differences in expression levels of genes for > 25 receptors were identified across cell types, ages, and arteries. Heat maps and distance matrices illustrate up‐ and down‐regulation of receptors for respective comparisons. The Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database was applied to predict downstream function and signaling pathways, to construct networks of co‐expression and predict protein interactions. Our findings illustrate pronounced differences in expression profiles between ECs and SMCs while revealing more subtle differences with aging and between vessel types.Support or Funding InformationNIH R37HL041026 & F32HL118836
Cardiac Stretch‐Induced Transcriptomic Changes Are Direction Dependent
Authors: Buchholz Kyle S. , Tan Philip , Zambon Alexander C. , Saucerman Jeffrey J. , McCulloch Andrew D. , Omens Jeffrey H. 
Published: November 2023

The goal of this study was to investigate the effect of the major axis of biaxial mechanical stretch on cardiomyocyte hypertrophic gene expression. Because cardiac hypertrophy can present itself as concentric or eccentric in vivo, we hypothesized that applying stretch in orthogonal directions to cardiomyocytes would produce divergent gene expression profiles. To investigate the directionally‐dependent cellular response to stretch, neonatal mouse cardiomyocytes were cultured on a deformable silicone membrane, which was micropatterned to create parallel grooves that aligned the cardiomyocytes. By adjusting the groove orientation relative to the stretcher axes, the primary direction of stretch could be applied parallel or transverse to the myofibril direction.We conducted RNA sequencing (RNA‐Seq) to examine whole genomic gene expression changes after acute cardiomyocyte stretch. The results showed a more robust gene response to longitudinal than to transverse stretch. After 30 minutes of stretch, 349 and 1161 genes were considered differentially expressed (DE) from transverse and longitudinal stretch, respectively. After 4 hours, the number of DE genes increased to 962 and 3925. Gene ontology analysis indicated enrichment of cell cycle and cell growth by both directions of stretch; whereas only longitudinal stretch caused enrichment of actin cytoskeleton organization and lipid metabolism.To further explore these gene expression changes, we constructed a logic‐based gene regulatory network from published data. From this network analysis, we identified SRF as a critical transcription factor in regulating longitudinal stretch‐induced gene changes. In addition, we performed Upstream Regulator Analysis in Ingenuity Pathway Analysis to identify putative transcription factors also responsible for stretch‐induced gene changes. These transcription factors include PPAR‐alpha, Klf15, and E2F1. The regulatory network model provides evidence that cardiomyocytes engage different transcriptional regulators in responses to different principal orientations of biaxial stretch.Support or Funding InformationSupported by: NIH grants P50 GM094503, 1R01HL105242, GM103426, and HL103566 and CIRM grant RT3‐07899.
Linking Metabolic and Structural Remodeling by Cardiac‐Specific Activation of the Mechanistic Target Of Rapamycin Complex 1
Authors: Davogustto Giovanni , Salazar Rebecca , Vasquez Hernan , Taegtmeyer Heinrich 
Published: November 2023

BackgroundThe heart remodels metabolically and structurally before it fails. Metabolically, the heart increases its reliance on carbohydrates for energy provision. Structurally, the heart hypertrophies to sustain increased hemodynamic stress. However, it remains unclear if both processes occur independently or if one is the consequence of the other. The activation of the mechanistic Target Of Rapamycin Complex 1 (mTORC1) pathway is closely tied to glucose uptake by the heart and also drives structural remodeling of heart muscle. With insulin stimulation or with increased workload, the glycolytic intermediate glucose 6‐phosphate (G6P) is required to activate mTORC1. Activation of this pathway leads to increased protein synthesis, hypertrophy and ER stress response leading to contractile dysfunction.ObjectiveWe examined whether sustained mTORC1 activation results in metabolic and structural remodeling in the heart, with special focus in the time course of these events.Methods and ResultsTo do this we developed a Cre‐LoxP mouse model to achieve inducible, cardiac‐specific deficiency of the protein tuberin (TSC2), a member of the tuberous sclerosis complex, a key inhibitor of mTORC1. Echocardiograms were performed at 5, 15 and 20 weeks after induction. Mice were sacrificed 2, 4, 5 and 20 weeks after induction. Hearts were harvested, their weight recorded, rapidly freeze‐clamped and stored for further analysis. Genomic DNA, total RNA and proteins were extracted for qualitative PCR, real‐time PCR and immunoblotting respectively. G6P levels were measured by spectrophotometric enzymatic analysis using G6PDH coupled to NADPH production with extinction at 340 nm. Histologic analysis using H/E stain was used to determine left ventricle wall size and cardiomyocyte size. Immunoblotting of protein markers confirmed TSC2 knock out and activation of mTORC1 downstream targets two weeks after induction. G6P was increased at 2 and 4 weeks after induction, before any structural change could be detected. Serial echocardiograms showed evidence of concentric hypertrophy 15 weeks after induction. Histologic analysis using H/E confirmed concentric hypertrophic remodeling at 20 weeks.ConclusionThe results indicate that inducible, sustained mTORC1 activation in the heart results in metabolic remodeling that precedes structural changes. We conclude that sustained mTORC1 activation is a key driver of the metabolic and structural remodeling preceding heart failure.Support or Funding InformationWork in our laboratory is supported by grants from the U.S. Public Health Service (R01 2HL 61483‐10, R01 HL 073162). GD receives fellowship support from The University of Texas System Medical Foundation.
Body Mass Index is a Strong Predictor of Low Serum 25(OH)D Levels in Multiethnic Obese Children in Western Massachusetts
Authors: KANNAN SRIMATHI , Visintainer Paul , Ganguri Harish B , Wittcopp Chrystal 
Published: November 2023

The objective of the study is to examine the association between low serum 25(OH)D levels (VDL) and BMI category in children, adjusting for sex, ethnicity, age, CVD risk markers, season and nutrient intakes. 99 obese (BMI> 95%) children aged 5–16 years participated in this cross sectional study conducted in a Pediatric Weight Management Clinic in Western Massachusetts. Nutrient intakes (Block Kids 2004 FFQ) and serum 25(OH)D were measured. Sunlight exposure, BMI, waist circumference (WC), BP, ethnicity, 25(OH)D, calcium, PTH, HbA1C, AST/ALT, fasting insulin, glucose, lipids and hsCRP data were obtained. Multivariable logistic regression was used to examine the relationship between VDL and BMI category, adjusting for potential confounders. Of 91 children completing the FFQ, mean 25(OH)D was 21.2 (±7.7) ng/mL and the mean BMI z‐score was 2.4 (±0.4). Using the Institute of Medicine (IOM) criteria, 25(OH)D was categorized into <15ng/mL (22.0%) and normal (≥15 ng/mL; 78%)., and BMIz, into >2.5 37.4%) and ≤ 2.5 (62.6%. Mean age 10.9±2.6 (SD) yrs, 22.0% African American, 26.4% Caucasian and 51.7% Hispanic, 52.8% female. Among those with BMI z‐scores less than 2.5, 15.8% had low 25(OH)D levels vs. 32.4% among those with BMI z‐scores at 2.5 or greater. That is, children with BMI z‐scores > 2.5 have 2.55 greater odds of having a low 25(OH)D level compared to those with BMI z‐scores <2.5 (OR=2.55, 95%CI: 0.93, 11.16; p=0.07). In logistic regression analysis, adjusting for gender, ethnicity, season, and age, children with BMI z‐scores >2.5 had a significant 5.14 greater odds of low 25(OH)D compared to children with BMI z‐scores ≤2.5 (95%CI: 1.30, 20.36; p = 0.02). Additional adjustment for energy‐adjusted nutrient values, waist circumference, and selected cardiovascular risk factors did not change this relationship. Obese children are at risk for vitamin D deficiency. This risk increases in children with severe obesity (BMIz > 2.5 SD) and is not significantly changed by season, ethnicity, nutrient intakes or sunlight exposure. More research is needed to further elucidate the mechanisms that influence vitamin D levels in this vulnerable population.Support or Funding InformationThis work was funded by UMASS‐Baystate Medical Center Collaborative Biomedical Research.
Urinary α‐CEHC Predicts α‐Tocopherol Status in Healthy Adults and Those with Metabolic Syndrome
Authors: Traber Maret G. , Leonard Scott W. , Mah Eunice , Bobe Gerd , Bruno Richard S. 
Published: November 2023

More than 90% of Americans do not consume the estimated average requirement (12 mg) of vitamin E, but dietary intakes are poorly correlated plasma α‐tocopherol (α‐T) concentrations, which are apparently normal. Plasma α‐T is an insensitive biomarker of α‐T status because α‐T increases with lipid levels and in individuals with hyperlipidemia, circulating α‐T increases, but delivery of both lipids and α‐T to tissues is compromised. We hypothesized that α‐carboxyethyl hydroxychromanol (α‐CEHC) and α‐carboxymethylbutyl hydroxychroman (α‐CMBHC), physiologic metabolites of α‐T that are generated in a cytochrome P450‐dependent manner, would reflect α‐T status, and function as indicators of the lower α‐T bioavailability in adults with metabolic syndrome (MetS). Age‐ and gender‐matched healthy and MetS adults (n = 10/group) completed a randomized cross‐over pharmacokinetics study in which they co‐ingested 15 mg hexa‐deuterium labeled (d6)‐RRR‐α‐T with non‐fat milk, reduced‐fat milk, whole milk, or soy milk prior to measuring by LC‐MS the 24 h urinary α‐CEHC and α‐CMBHC excretion and 0–72 h plasma α‐T, α‐CEHC, and α‐CMBHC (ClinicalTrials.gov #NCT01787591). We showed previously that MetS adults had lower d6‐α‐T bioavailability (AUC0–72 h) and estimated d6‐α‐T absorption compared to healthy adults regardless of dairy milk co‐ingestion. We report herein that plasma d6‐α‐CEHC AUC0–72 h was 50% lower in MetS adults (P<0.05); 24 h urinary concentrations of unlabeled α‐CEHC and α‐CMHBC, and d6‐α‐CEHC and d6‐α‐CMHBC, were also ~50–60% lower in MetS compared to healthy adults (P<0.005). Plasma d6‐α‐T AUC0–72 h (μmol/L*h) was correlated with urinary excretion of d6‐α‐CEHC and d6‐α‐CMBHC (μmol/g creatinine, both P<0.0001), as well as with plasma d6‐α‐CEHC AUC0–72 h (nmol/L*h). In summary, labeled urinary metabolites of α‐T correlate highly with α‐T bioavailability of recently ingested α‐T. Urinary α‐CEHC, and α‐CMBHC may be useful biomarkers to non‐invasively assess α‐T adequacy, especially in populations with dyslipidemia‐associated impaired α‐T trafficking.Support or Funding InformationSupported in part by DSM Nutritional Sciences, the National Dairy Council, and NIH (DK081761, UL1TR001070)