bluuebunny/crossref_metadata_2025 huggingface dataset:
Increases in cardiac vagal modulation following a single session of passive calf stretching
Authors: Lehnen Georgia , Araujo Marcela , Rocha Igor , Vianna Lauro , Trajano Gabriel
Published: May 2024

Autonomic cardiovascular responses to mechanoreflex activation by passive muscle stretching have been shown in numerous investigations. These cardiovascular adjustments include cardiac vagal inhibition, sympathetic activation, pressor response, and baroreflex resetting. However, it is currently unclear how the autonomic system responds after a single session of passive muscle stretching. Therefore, we aimed to test the hypothesis that there would be parasympathetic dominance after stretching cessation. Twenty-four volunteers (14 men; 22±3 yr) performed two protocols: 1) five sets of 1 minute of unilateral passive calf stretching with 15 s of rest; and 2) control condition (six minutes of resting at the same position). The autonomic cardiac responses of both control and experimental conditions were assessed before, and immediately, 15 minutes and 30 minutes after stretching cessation. Passive stretching was performed on an isokinetic dynamometer (Biodex System 4, USA). Heart rate, systolic and diastolic blood pressure were continuously measured on a beat-to-beat basis using lead II electrocardiography (BioAmp, MLA2540) and finger photoplethysmography (Human NIBP, Australia). Brachial arterial blood pressure was also measured with an automated digital sphygmomanometer (Dixtal, DX2022, Brazil). Heart rate variability (HRV) was determined following the guidelines of the Task Force of the European Society of Cardiology and the North American Society of Pacing. With regards to the hemodynamics variables, there was no significant difference in the heart rate before and after passive stretching, while mean blood pressure (MBP) was slightly higher (±2mmHg) 30 min following both protocols (control, p=0.027 and stretch, p=0.035). Regarding HRV analysis, in the time domain, RMSSD was significantly increased 30 min following passive stretching (+15%; p=0.029), and this effect was also detected when using the frequency domain (high frequency: +37%, p=0.039). Of note, our major findings were not affected by sex. In conclusion, autonomic cardiovascular control shifts to a parasympathetic dominant state following passive calf stretch, and the effect peaks around 30 minutes after stretching. Passive stretching seems to be a safe, easy, and effective form of exercise that evokes autonomic cardiovascular responses during and following its cessation, even if it is performed in a single session of stretch.

CNPq 307764/2022-2; CAPES (001) QUT South America Scholarship.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Belonging and Representation in Physiology Teaching
Authors: Co Elizabeth
Published: May 2024

We teach in a discipline that should be agnostic to race, class, gender and ability, as we are literally in the work of learning about all bodies. Yet, so often we hold up one example and call it “normal.” By presenting images, using language and communicating an understanding that lacks representation we are committing a double failure. We uniquely have the opportunity to help raise awareness and ultimately contribute to a reduction in health care disparities by presenting more equitable and representative information to our students during their journey to become health care providers and researchers. Two, we have the ability to increase student beloning and reduce stereotype threat when we provide examples that include our students' identities. In this talk we will discuss some of the ways that representation and belonging can be addressed within undergraduate physiology curriculum.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Feasibility of Improving Glycemic Control via Heat Therapy in individuals at risk for Alzheimer’s Disease (FIGHT-AD): a pilot study
Authors: Blankenship Anneka , Kueck Paul , Vitztum Michelle , Jensen Reilly , Kemna Riley , John Casey , Vidoni Eric
Published: May 2024

Impaired glycemic control increases the risk for type 2 diabetes and Alzheimer’s Disease (AD). Mechanisms such as impaired energy metabolism, cellular bioenergetic function, reduced intracellular protein homeostasis, and inflammation are all potential contributors to AD pathology. Heat therapy, via hot water immersion, has been shown to improve blood glucose regulation, insulin resistance, and inflammation. Given the potential contribution of these factors to brain health, heat therapy could offer immense clinical benefit to individuals at risk for AD. We performed a pilot study to test the feasibility of utilizing heat therapy in older individuals at risk for AD due to metabolic risk. The study intervention involved two pre-visits which included a cognitive function screen, sleep, diet, and physical activity questionnaires, as well as a glucose tolerance test and MRI scan. The intervention consisted of four weeks of heat therapy (3 visits/wk) for a total of 12 visits, followed by two post-intervention study visits identical to the pre-study visits. A total of 18 individuals (9 male, 9 female), average age 71.1 ± 3.9 y completed the intervention. Participants demonstrated metabolic risk based on average HbA1c values of 6.6 ± 0.67, Body Mass Index (BMI) of 29.1 ± 5.4, and 15 of the 18 participants were on hypertensive medications. Our cohort was highly diverse, with 33% underrepresented minority group representation. We had 96% participant adherence for the study (8 missed visits out of 216 total visits), and 1 study related Adverse Event (mild dizziness/nausea) that was mild. Overall, the research participants responded to a post-intervention survey saying they enjoyed participating in the study and it was not a burden on their schedules. In addition, we obtained preliminary data demonstrating a significant effect of the heat therapy intervention on body mass index, mean arterial pressure, and cerebral perfusion (p<0.05), and a trend for improved self-reported sleep quality (Pittsburgh Sleep Quality Index; p=0.06). Future studies of longer duration are needed to provide a comprehensive understanding of the impact of heat therapy on glucose homeostasis and brain health.

NIH P30 AG035982 (KU ADRC), pilot funds to PCG.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Therapeutic potential of hiPSC-derived cardiomyocytes for Duchenne Muscular Dystrophy
Authors: Wang Ruchen , Perlingeiro Rita , van Berlo Jop
Published: May 2024

Duchenne Muscular Dystrophy (DMD) results in progressive and incurable cardiomyopathy, leading to significant morbidity and mortality due to heart failure. There is currently no effective cure for DMD that can correct the genetic defects and compensate for the lack of dystrophin. Therefore, the therapeutic strategies that focus on the transplantation of induced pluripotent stem cells (iPSCs) derived cardiomyocytes are promising options, and remain to be investigated to which extent they can restrain the cardiomyocyte loss phenotype and improve cardiac function. There has been significant progress in the differentiation of cardiomyocytes (CMs) from hiPSCs (human iPSCs). Three hiPSC lines: AICS-0011, 029 iPS clone 4-PCBC, and PCBC16iPS were investigated based on previously published culture and differentiation methods. We will inject differentiated CMs into the heart of Mdx mice that are mutated or deficient for NOD-scid, IL2Rg to allow for xenotransplantation engraftment. Having confirmed the effcient differentiation of CMs from all three hiPSC lines, the next step will be to transplant CMs. The engraftment rate after transplantation will be quantified by IHC staining for human lamin A/C and the relative level of genomic human DNA from isolated hearts. Correction of dystrophin expression will be measured via IHC for dystrophin. Echocardiography will be performed to measure improvement in cardiac systolic or diastolic function. If therapeutic transplantation of hiPSC-CMs is possible, it could improve the survival of DMD patients.

This project was supported by RMM091621DS008, NIH155993, and NIH160665.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Is the Serpin-Enzyme Complex Receptor an Orphan G-Protein Coupled Receptor?
Authors: Mahmood Ammar , Cortner Loki , Rahimi Nastaran , Samson Willis , Yosten Gina
Published: May 2024

Alpha-1 antitrypsin (α1-AT) is a member of serine proteinase inhibitors, collectively known as serpins, that inactivate their target enzymes by forming a stabilized serpin-enzyme complex. α1-AT molecules interact with elastase, forming biologically active complexes. It was suggested that the formation of α1-AT-elastase complex would expose a domain from α1-AT molecule that is recognized by a specific cell receptor. Thus, a synthetic peptide, called 105Y, was made based on the sequence of the exposed domain. The peptide binds specifically to human hepatoma HepG2 cells, human monocytes, human neutrophils, and rat pheochromocytoma cells (PC12). This binding is blocked by α1-AT-elastase complex and other serpin-enzyme complexes, suggesting an existence of a specific cell surface receptor, termed SEC receptor, that recognizes serpin enzyme complexes. However, the identity of SEC receptor is still unknown. Thus, we decided to use the Deductive Reasoning Strategy approach to investigate if the SEC receptor belongs to G-protein-coupled receptor (GPCR) family. We measured responsiveness of HepG2 cells as well as human neuroblastoma SHSY5Y cells to 105Y peptide by quantifying their expression of an early response gene c-Fos using real time quantitative polymerase chain reaction (qPCR) and measured their expression of orphan GPCRs using polymerase chain reaction (PCR) followed by gel electrophoresis. Our results indicate that the cells were responding to 105Y peptide and express certain orphan GPCRs. Our goal is to evaluate the necessity of these oGPCRs in 105Y peptide signaling in order to determine the best candidate(s) for the 105Y receptor. These results would shed light on the identity of the SEC receptor for better understanding of the molecular biology and physiology of the serpin-enzyme complexes and their receptors.

National Institute of Health.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Identification of Spinal Afferent Innervation in the Rat Heart: Atria and Ventricles: Anterograde Tracing
Authors: Ma Jichao , Bizanti Ariege , Barton Kayla , Kwiat Andrew M. , Nguyen Duyen , Bendowski Kohlton T. , Madas Jazune
Published: May 2024

The spinal afferent innervation of the heart regulates cardiac functions by sending sensory information from the dorsal root ganglia (DRG) to the brain. However, the distribution and morphology of spinal afferents in the whole heart are not well characterized. The challenges here are: 1) diffculty in surgically accessing the upper thoracic DRG to label only cardiac spinal afferents. 2) handling flat-mounts of whole atria and ventricles (thickness ~850 μm) without using sections or partial tissues that could disrupt the continuity of axonal structures. To overcome these challenges, we injected anterograde tracer dextran biotin (DB) into the left DRG (C8-T3) of male SD rats (3-5 months) and allowed them to recover for 14 days for tracer transportation. Flat-mounts of the left and right atria and ventricles were prepared, and DAB (3,3′-Diaminobenzidine) stained, followed by imaging, tracing, and digitization using the Neurolucida system. Our findings are: In the atria, the DB-labeled axons entered the atria potentially through the left precaval vein (LPCV), with predominant innervation of the left side of the atrial wall and extended their projection towards the auricles, middle region of the atrium, and pulmonary veins. Most of the spinal afferent axons were present in the myocardial layer. Varicose DB-labeled axons were also observed on cardiac targets at different regions, and distinct morphological structures were found. In the cardiac muscle, DB-labeled axons ran mainly in the direction of muscle fibers. Also, varicose axons ran along the small vasculature on the atria. Spinal afferents formed varicose contacts with individual principal neurons within some intrinsic cardiac ganglia (ICG). In the ventricles, DB-labeled axons were present in the left and right ventricles, which ramified and expressed spherical-like varicosities on the cardiac muscle. In both the atria and ventricles, spinal afferent axons formed simple, branching, and complex terminal structures. Thus, our work, for the first time, successfully labeled, traced, and digitized the spinal cardiac afferents in the flat-mounts of whole atria and ventricles, which will provide a foundation for specific labeling of cardiac spinal afferent fibers. In addition, it will lead to the future study of topographical cardiac spinal afferent innervation, functional studies, and their remodeling in pathological conditions.

This study was supported by NIH HEAL/SPARC U01 NS113867-01, NIH R15 R15HL137143-01A1, and UCF dissertation completion Fellowships.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
E-Cigarette Aerosol Inhibition of Compositionally Different Surfactants
Authors: Graham Emma , Gehani Sabrine , Veldhuizen Ruud
Published: May 2024

Introduction: Pulmonary surfactant lines the alveolar surface where it reduces surface tension (ST) thereby facilitating breathing with minimal effort. As such, impairment of surfactant’s surface tension reducing function can contribute to lung injury. Isolated surfactant from the lung consists of up of 85-90% by weight saturated and unsaturated phospholipids, 5-10% neutral lipids, mainly cholesterol, and 10% surfactant proteins, designated SP-A, SP-B, and SP-C. However, studies examining surfactant function and dysfunction have often utilized surfactants with simpler compositions. One recent area of interest is the impact of e-cigarette (EC) generated aerosols on surfactant. EC use remains a popular habit despite reports of vaping associated acute lung injury. Upon inhalation, EC aerosol comes into direct contact with pulmonary surfactant and previous studies have demonstrated that EC aerosol exposure can impair surfactant function using either bovine lipid-extracted surfactant (BLES) or simple lipid mixtures. Comparing inhibition by EC aerosol of a more diverse set of surfactant preparations can further elucidate which components of surfactant are most affected by EC aerosol. We hypothesized that EC aerosol would cause varying degrees of functional inhibition in compositionally different surfactants. Methods: The following surfactant preparations were tested: BLES, BLES + SP-A, natural bovine, SP-A deficient bovine, and synthetic surfactants composed of saturated lipids + cholesterol + SP-C, and saturated + unsaturated lipids + cholesterol + SP-C. To test the exposure to EC aerosol, 2ml of surfactant was placed in a syringe (30ml) attached to an EC. The generated aerosol was drawn into the syringe for 30 sec and then expelled, this was repeated 30 times. The functional impact was then tested on a constrained sessile drop surfactometer to analyse changes in ST reduction. Results: Upon exposure to EC aerosol, natural bovine surfactant had significantly higher minimum ST compared to non-exposed and BLES. This difference did not appear to be mediated by SP-A. Synthetic lipid mixtures containing only saturated phospholipids (DPPC) were not significantly inhibited by EC aerosol, but the addition of unsaturated lipids resulted in increased minimum ST. Conclusion: Functional impairment of pulmonary surfactant due to EC aerosol is dependent on aerosol interaction with unsaturated lipids. This effect is more pronounced in natural complete surfactants.

Western, NSERC, OGS.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Compound 48/80 causes overactive bladder without altering urothelial permeability in mice
Authors: Flood Emma , Jones Brothely , Jackson William , Tykocki Nathan
Published: May 2024

The urothelium, a transitional epithelium lining the urinary bladder, is essential for preventing leakage of urine into the underlying tissue. Disruption of this barrier by noxious stimuli or inflammatory mediators increases bladder wall permeability and causes bladder dysfunction. Compound 48/80 is a pro-inflammatory basic secretagogue that causes urothelium-dependent increases in urinary bladder contractility, as well as bladder overactivity in mice. We hypothesized that Compound 48/80 causes bladder dysfunction by increasing urothelial permeability. Intact bladders from male C57BL/6 mice (N=4) were cannulated, filled with HEPES-buffered physiological salt solution containing FITC-labeled-dextran (70 kDa), and pressurized to 25 mmHg. Z-stacks of baseline fluorescence were captured across the bladder wall using 2-photon laser microscopy. Compound 48/80 (50 μg/mL) was then instilled intravesically for 10 minutes before the bladder wall was imaged again. Average FITC intensity plots wall showed no consistent increase in fluorescence with or without Compound 48/80 from the lumen into the bladder wall. There was also no statistical difference in the area under the curve of these line graphs (p=0.5898). Our findings suggest that Compound 48/80 causes overactive bladder without affecting urothelial permeability. Future studies will investigate other secretagogues and lower molecular weight dextrans to clarify the mechanisms by which secretagogues cause a loss of urothelial barrier function.

This research is supported by NIH P20-DK127554 (NRT), NIH R01-DK119615 (NRT).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Effects of Aging and Fatigue on Human Skeletal Muscle Cellular Contractile Function
Authors: Ricci Austin , Privett Grace , Callahan Damien
Published: May 2024

Aging is associated with a reduction in skeletal muscle mass and function, known as sarcopenia. While reductions in contractile force are typically explained by loss in muscle cellular cross sectional area (CSA) loss of contractile power during high velocity contractions exceed reductions in force and cannot be solely explained by loss of muscle size and are observed at the single fiber within the same myosin heavy chain isoform (MHC). These phenomenon may be explained by myosin binding protein C (MyBP-C), which is known to modulate contractile force and velocity in a phosphorylation-dependent manner in both cardiac and skeletal muscle. Few studies have investigated the inherent contractile performance of single fibers between old and young adults, and none have explored the effects of altered MyBP-C phosphorylation on single fiber function. Therefore, the PURPOSE of this study was to investigate the effects of age and fatigue-induced MyBP-C phosphorylation on single fiber contractile performance. We HYPOTHESIZED that isometric tension will be enhanced in older adults but velocity and power will be reduced, and fatigue will enhance velocity and power in single fibers. To test this hypothesis, we recruited 4 young (18-35) and 3 older (65-80) adult males to perform a single bout of unilateral knee extensions at 30% maximal voluntary isometric contraction (MVIC) until task failure. Immediately following, a bilateral biopsy of the vastus lateralis (VL) muscle was performed on the fatigued and non-fatigued control limbs. Tissue was either flash frozen for western blot or prepared for mechanical analysis of single fiber tension (Tmax), velocity (Vmax), and power (Pmax) under optimal intracellular metabolic conditions. Our analyses were limited to MHC IIA due to differences in fiber type distribution between the groups. Our RESULTS showed that neither age nor fatigue had an effect on contractile performance in MHC IIA fibers. However, independent analysis of fatigue within age groups suggest trends towards an increase in velocity (p=0.055) in young (MHC IIA) and reduction in tension (p=0.085) in old (MHC I) adult fibers. We CONCLUDE that fatigue may modulate contractile function in the single fiber in an age- and fiber-type dependent manner. Future studies will be aimed at collecting multiple fiber types and investigating the role of biological sex.

Wu Tsai Human Performance Alliance.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The Integrated Stress Response Regulates Diurnal Rhythms in Liver Metabolism
Authors: Levy Jordan , Mirek Emily , Cao Ruifeng , Anthony Tracy
Published: May 2024

Disruptions in biological rhythms are associated with the development of metabolic diseases. General control nonderepressible 2 (GCN2), a primary sensor of amino acid insuffciency and activator of the integrated stress response (ISR), plays an integral role in liver metabolism. The objective of this work was to examine the impact of feeding a low protein quality (LPQ) diet on diurnal rhythms in liver metabolism. We hypothesized that activation of the ISR by GCN2 maintains metabolic rhythms within the liver during LPQ feeding. To address our objective, wild type (WT) and whole body Gcn2 knockout (GCN2KO) mice were housed in total darkness and provided free access to either a Control or a LPQ diet (devoid of leucine) for 8-days and then killed at 2 circadian time (CT) points 12-hours apart (CT3, CT15). WT mice fed a Control diet showed oscillations in hepatic ISR activation that were lost in the livers of GCN2KO mice. Diurnal patterns in the liver transcriptome including genes regulating triglyceride metabolism were also dampened in GCN2KO mice. WT mice fed LPQ showed increased hepatic ISR activation and greater abundance of ISR target genes relative to Control only at CT15 (p<0.05 by two factor ANOVA). GCN2KO mice fed LPQ failed to show oscillations in ISR activation and instead displayed reductions in liver intracellular amino acids alongside significant upregulation of genes encoding gluconeogenesis and amino acid catabolism at CT15 (q<0.05, Log2FC>1). In conclusion, GCN2 is required for diurnal ISR activation and execution in the liver. LPQ feeding increases hepatic ISR activation in a time dependent manner. Sensing of LPQ by GCN2 is necessary for the maintenance of rhythms in liver macronutrient metabolism.

NIH DK109714, Pilot award from the NJ IFNH Center for Human Nutrition, Exercise, and Metabolism (NExT).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sex-Specific Regulation of Catecholamine Signaling in Rats Exposed to Dexamethasone In Utero and Angiotensin in Adulthood
Authors: Alvarez Jared , Sharma Arpan , Madhavpeddi Lakshmi , Hale Taben
Published: May 2024

Pregnant women who are at risk of pre-term delivery are given the synthetic glucocorticoid dexamethasone (DEX) to stimulate fetal lung development as it is not degraded by 11ß-hydroxysteroid dehydrogenase, enabling DEX to freely cross through the placenta and act on the developing fetus. Our lab has previously found that in-utero DEX exposure increases stress-induced blood pressure and heart rate responses in female, as well as autonomic dysregulation in the adult offspring. Angiotensin II (Ang II) induces hypertension and cardiac remodeling in part through activation of the sympathetic nervous system. Given these prior findings, this project explores whether prenatal DEX exposure alters the response of Ang II on cardiac sympathetic nervous system regulation. Pregnant rats were administered either vehicle (20% w/v 2-hydroxypropyl ß-cyclodextran) or the glucocorticoid DEX (0.4 mg/kg body weight, i.p) on gestation days 18-21. When offspring reached ~15 weeks of age, groups were administered either subcutaneous AngII (200 ng/kg per min) as a cardiovascular challenge or saline as experimental control for four weeks. To measure local sympathetic signaling, tyrosine hydroxylase (TH) was analyzed as it serves as the rate limiting step of catecholamine synthesis while catechol-O-methyltransferase (COMT) was selected as it catalyzes catecholamine breakdown. Gene expression of adrenoreceptor ß1 ( Adrb1) was measured to assess receptor availability for sympathetic activity. Data were analyzed by 3-way ANOVA with sex, prenatal treatment (i.e., DEX vs. Vehicle), and postnatal treatment (i.e., saline vs. AngII) as the variables. There was an overall main effect of prenatal DEX treatment to reduce TH expression in the LV (p=0.018), an effect that was more pronounced in males. COMT expression was found to be significantly impacted by sex, prenatal treatment, and post-natal treatment (3-way interaction, p=0.016). Thus, the degree to which DEX and Ang II impacted COMT expression differed by sex. There was a sex x postnatal treatment interaction (p=0.013) on ADRB1 expression whereby expression was increased by Ang II only in female hearts. Although prior studies have shown that Ang II can increase local sympathetic activity in the heart, the present data suggest that prenatal treatments disrupt this response in a sex-specific manner. Moreover, sex and prenatal treatment were greater drivers of local sympathetic regulation than Ang II.

NIMH/ORWH 1U54MH118919.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
High Fat Diet Induced Lipid Deposition and Perilipin 2 Expression in Mouse Liver Is Attenuated by Endothelin-1 Receptor A Blockade
Authors: Sileshi Yamrot , Wilson Natalie , Mills Megumi , Speed Joshua
Published: May 2024

Obesity is associated with dyslipidemia and lipid deposition into liver tissue. Circulating endothelin-1 (ET-1) is elevated in patients with obesity, and our lab has demonstrated that ET-1 is increased in liver of mice fed high fat (HFD). Interestingly, treatment with atrasentan attenuates reduces circulating triglycerides and free fatty acids and reduces lipid deposition into liver of mice fed HFD for 10 weeks; however, the mechanisms are not known. Perilipin 2 (Plin2) is a protein expressed in adipocytes and hepatocytes that is integral to lipid droplet formation by forming a coating around the droplet. We hypothesized that ET-1 receptor blockade reduces liver lipid deposition in obese mice by reducing Plin2 expression. To test this hypothesis, mice were fed normal (NMD) or HFD for 10 weeks and treated with the ET-1 receptor A (ETA) antagonist atrasentan for weeks 9-10. ET-1 receptor expression was significantly increased in HFD fed mice compared to NMD. As previously demonstrated, HFD fed mice had significantly higher liver triglyceride content compared to NMD controls, and this was attenuated in mice treated with atrasentan (ATR). As expected, Plin2 expression in liver tissue was significantly elevated in HFD mice compared to NMD (91.7±17.4 vs. 60.8±14.4 copies/pg RNA), an affect that was abolished in mice treated with atrasentan (NMD, 60.8±14.4; HFD, 91.7±17.4; NMD + ATR, 70.2±10.8; HFD + ATR, 26.3±5.8 copies/10pg RNA). These data suggest that ET-1 promotes lipid accumulation in liver of obese mice by reducing Plin2 expression.

Funding: R01 DK124437, P30GM149404, and T32HL105324.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Genomic Insights into Diving Adaptations of Extreme Pinniped Divers: A Comparative Study of Elephant and Weddell Seals
Authors: Moreno Santillan Diana , Vazquez-Medina Jose Pablo , Hindle Allyson
Published: May 2024

Extreme pinniped divers are extraordinary models to study adaptations to hypoxia/reoxygenation events derived from extreme fluctuations in oxygen levels during deep diving. We analyzed the evolutionary adaptations of the Weddell seal ( Leptonychotes weddellii) and the Northern and Southern elephant seals ( Mirounga angustirostris and M. leonina), which have exceptional diving abilities, reaching depths of over 1000 meters for extended periods up to 90 minutes. To understand the molecular mechanisms underpinning these remarkable adaptations, we conducted a comprehensive comparative genomic analysis of thirteen pinniped species. Our gene family evolution analyses revealed a significant loss of function in genes involved in the enzymatic degradation of glutathione, an endogenous antioxidant that our functional analysis have previously shown to increase rapidly in response to hypoxia exposure in primary cells derived from extreme divers, likely to protect cells against oxidative damage. We also detected adaptive signatures in pathways involved in the optimization of mitochondrial respiration, energy metabolism, DNA repair and cardiovascular regulation in these extreme divers. Notably the Weddell seal exhibited more genes under positive selection compared to the Elephant seals, possibly reflecting adaptations to extreme environmental pressures. Pathways enriched in Weddell seals include those related to fat metabolism, oxidative damage against hydrogen peroxide and membrane lipid remodeling. Our analysis sheds light on the remarkable genomic adaptations that enable extreme pinniped divers to tolerate oxygen fluctuations associated with deep diving while offering valuable insights into their unique physiological and biochemical strategies for overcoming the challenges posed by hypoxia and reperfusion damage.

NSF OPP 2020664.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The Role of Microvascular Rarefaction in Dysfunctional Pericardial Adipose Tissue
Authors: Fopiano Katie Anne , Cotton Claire M , Patel Vijay S , Bagi Zsolt
Published: May 2024

Pericardial adipose tissue (PAT) in obesity has been shown to be an independent risk factor for coronary heart disease but the underlying mechanism remains incompletely understood. We aimed to elucidate the interrelationship between PAT expansion and the adipose tissue vascularization. PAT samples were collected from patients with coronary heart disease (19 patients; age: 48-79; BMI: 22.29-41.09). Tissue samples were stained using H&E and the number and size of adipocytes was quantified using unbiased techniques via AdipoCount and ImageJ. PAT samples, cut 40 μm thick, were immunolabelled using DyLight 594 fluorescent tomato-lectin dye followed by quantification of the tissue vasculature using an unbiased, automatic 3D reconstruction (Vesselucida360). Angiogenesis was quantified using an ex vivo angiogenic assay whereby pericardial vessels were isolated, cut, and embedded in a collagen matrix sustained with growth factors; number of sprouts were used as a measure of angiogenic potential and were further analyzed for length and branching in ImageJ. Patients exhibited an increased adipocyte size as BMI increased with measures of vascularization, such as number of branching nodes and total vessel length, showed a negative correlation to increasing BMI. Vessel volume and vessel surface area showed no correlation to patient BMI. Angiogenic potential, measured by the number of vessel sprouts, sprouting length, branching length, and branching interval, showed a significant association with increasing BMI. Our data show that while adipocyte size increases with an increasing BMI, the PAT vascularization had a negative correlation to increasing BMI. These results suggest that the vasculature is insuffcient to supply the increasing PAT demand, leading to impaired perfusion and eventual adipose tissue dysfunction. However, there was a significant increase in angiogenic potential that shows that when provided with growth factors, these vessels have the ability to increase their angiogenic potential, yet in vivo the vascular angiogenic response may be hindered, which needs to be further studied.

T32 HL155011 (KAF) F31 NS132564 (KAF).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Muscle function and structure in a mouse model of dysfunctional central nervous system myelin
Authors: Manzoor Iman , Dagostino Gino , Alshawabkeh Zaid , Tajaldeen Jawad , Greger Devin , Gow Alexander , Roche Joseph
Published: May 2024

INTRODUCTION. Claudin-11(CLDN11)-deficient mice have been reported to have dysfunctional central nervous system myelin, and altered motor control and muscle tone in their hindlimbs. OBJECTIVE. We compared CLDN11-deficient mice with strain-, age-, and sex-matched controls (CLDN11-suffent mice). We hypothesized that CLDN11-deficient mice will have reduced muscle strength and will show a greater resistance to high stretch velocities compared to their CLDN11-suffcient counterparts. METHODS. We studied the ankle dorsiflexor and plantarflexor muscles in a convenience sample of ten CLDN11-deficient and four CLDN11-suffcient mice (3-4 months, males). We recorded the maximum isometric contractile torque of the ankle plantarflexor and dorsiflexor muscles measured in milli-Newton-millimeter (mNmm), and the maximum contractile torque at low (100 °/s) and high (1200 °/s) muscle stretch velocities during eccentric contractions to assess spasticity. We also studied structural changes in muscle cross sections stained with hematoxylin and eosin. RESULTS. Data are reported as mean ± SD. Maximum plantarflexor contractile torque was 7800 ± 1651 mNmm and 9646 ± 2637 mNmm in CLDN11-deficient and -suffcient mice, respectively. Maximum dorsiflexor contractile torque was 1956 ± 347 mNmm and 2975 ± 195 mNmm in CLDN11-deficient and -suffcient mice, respectively. Spasticity assessed as the ratio of maximum eccentric torque measured at 1200 °/s to 100 °/s was 0.94 ± 0.07 and 0.93 ± 0.01 in the plantarflexors of CLDN11-deficient and -suffcient mice, respectively, and 1.41 ± 0.19 and 2.1 ± 0.33 in the dorsiflexors of CLDN11-deficient and -suffcient mice, respectively. One-way ANOVAs indicated that CLDN11-deficient and -suffcient mice were not statistically different (p>0.05) in maximum torque production and spasticity. CLDN11-deficient mice showed no remarkable alterations in muscle structure. CONCLUSION. Claudin 11 deficiency in mice does not affect maximum contractile torque and stretch-velocity-dependent muscle tone when studied by robotic dynamometry under general anesthesia, nor does it prominently affect muscle structure.

We thank the WSU UROP funding mechanism for supporting Ms. Iman Manzoor’s involvement on this project. We thank the Wayne State University Doctor of Physical Therapy (DPT) Program for supporting student research and providing research training through coursework and research experiences. We thank Dr. Alexander Gow for sharing mice and mentorship.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Cells expressing POLG loss-of-function variants can decrease mtDNA copy number and increased growth rates in neighbouring A7r5 and HeLa cells
Authors: Poburko Damon , Rothwell Samantha , Taha Omnia , Ng Irvin , Baniqued Angelica , Paris Italia , Shalchy-Tabrizi Sophia
Published: May 2024

Mitochondrial disfunction promotes vascular disease, and mitochondrial diseases offer valuable insights into the pathological mechanisms of mitochondrial dysfunction. We previously described a patient cohort with variants in the mitochondrial DNA gamma polymerase (POLG) that were prone hypertension. We hypothesized that the POLG variants promote hypertrophy or hyperplasia of vascular smooth muscle cells in a way that stiffens or thickens blood vessels to explain the high rate of resistant hypertension in this cohort. The objective of this study was to assess the cellular phenotype of cells over-expressing POLG variants: pathogenic Y955C and variants of unknown significance; R964C, I1098N, Y1138C. We transiently expressed human FLAG-tagged POLG variants in rat A7r5 and HeLa cells for 2-4 days. Transfection effciency ranged from 20-30% in A7r5 and >60% in HeLa cells. POLG variants increased cell density by nuclear counting (20-60%) and growth rates measured by 48-72 h of live-cell imaging (Y955C > R964C > I1089N » Y1138C). Compared to wild-type, Y955C and R964C reduced mtDNA copy number (mCN) measured by droplet digital PCR by 10-20%. Imaging mtDNA nucleoids (anti-dsDNA) and the FLAG-tag showed that reduced mCN was not restricted to transfected cells. Addition of a P2A-T2A-nuclear-EGFP to the POLG constructs demonstrated that faster growth rates were not specific to transfected cells. Resting and oligomycin-stimulated mitochondrial membrane potential imaged with TMRM were unaffected by Y955C and R964C. Mitochondrial ROS (mitoSox) was similar between cultures transfected with Wild-type versus POLG variants and lower than levels stimulated by antimycin-A’s inhibition of complex III. Notably, we found a linear relationship between mCN and cell density that was not simply due to smaller cell size at higher densities. Using Hoescht-33342 staining to assess cell cycle, no clear difference in cell-cycle distribution was evident in unsynchronized cultures. We conclude that modest reduction of mCN induces a mitogenic effect, likely via a diffusible messenger that further reduces mCN in a cell population. The signalling mechanism of this phenomenon remains to be identified, but our results confirm that POLG malfunction can alter smooth muscle physiology in a way that could support pathogenic vascular remodelling and could promote enhanced growth in cancerous cells.

Funded by the Natural Sciences and Research Council of Canada.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Chlorpyrifos-Induced Airway Hyperreactivity in Rats Is Dependent on NK1 Receptor Signaling
Authors: Grodzki Ana Cristina , Schelegle Edward , Lein Pamela
Published: May 2024

Occupational and environmental exposures to organophosphorus pesticides (OP) are associated with increased asthma incidence. While the canonical mechanism of OP neurotoxicity is acetylcholinesterase (AChE) inhibition, we previously demonstrated that the OP chlorpyrifos (CPF) causes airway hyperreactivity (AHR) in adult rats 24 h after exposure at levels that do not significantly inhibit AChE. Here we further investigated the persistence of CPF-induced AHR at 7 days post-exposure and tested the hypothesis that neurogenic inflammation contributes to CPF-induced AHR. Eight-week-old male Sprague Dawley rats were administered 30 mg/kg CPF subcutaneously, and AHR was assessed at 24 h or 7 days post-exposure using a Flexivent mechanical ventilator during electrical stimulation of the vagus nerves. CPF significantly increased airway resistance and elastance at 24 h and 7 days post-exposure. The NK1 antagonist SR140333 was used to evaluate the involvement of substance P and its receptor NK1 in CPF-induced AHR. SR140333 was injected into rats 1 h before mechanical ventilation and vagal stimulation. NK1 receptor inhibition decreased vagally stimulated bronchoconstriction in CPF-exposed male animals to that observed in vehicle controls, at 24 h and 7 days post-CPF exposure. These data suggest that substance P signaling contributes to both acute and persistent CPF-induced AHR. These findings have significant implications for assessing the risk to human health and safety of CPF, and potentially other OPs, and indicate a potential new therapy for mitigating AHR in intoxicated individuals.

This work was supported by the NIH (grants R01 ES017592 and T32 HL07013).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Development of a Case/Problem-Based and Teamwork-Focused Applied Physiology Course to Graduate Students Planning to Apply to Dental School
Authors: Schonhoff Christopher , Lopez Marisol , Lehman William , Young Aaron
Published: May 2024

The Master of Science in Oral Health Sciences (OHS) at Boston University Chobanian & Avedisian School of Medicine is explicitly designed for students who wish to improve their academic preparedness for dental school admission. Oral Health Sciences students take some courses, including the first-year Dental Physiology course, alongside dental students at Boston University Henry M. Goldman School of Dental Medicine (GSDM). Since students in the OHS program often struggle in the largely lecture-based Dental Physiology course, we developed a case/problem-based and teamwork-focused Applied Physiology course that ran parallel to the Dental Physiology course in the fall of 2023. The primary goal of the Applied Physiology course is to provide additional instruction and academic support and to present course material in a team-based learning mode for the OHS students. We hypothesized this approach to learning physiology would help to improve student mastery of physiology content critical to their future success. The objective of the current study was to assess the effectiveness of the new Applied Physiology course in enhancing OHS students' motivation and academic performance in the Dental Human Physiology course. We are evaluating the benefits of this course by comparing Dental Physiology final grades and individual exam grades between dental students and OHS students. In addition, we are comparing course performance for OHS students from previous class years who did not take the Applied Physiology course against students from the current academic year who took the course. Our preliminary results indicate students who took the Applied Physiology course in the fall of 2023 performed better in the Dental Physiology course than last year’s OHS students. The mean grade for Dental and OHS students in Dental Physiology in the fall of 2023 was 82.3% ± 12.3% and 80.3% ± 13.9% respectively. In contrast, the mean grades for Dental students in the fall of 2022 was 82.7% ± 8%, while OHS students’ mean was much lower at 74.7% ± 11%. Analysis and comparisons for individual course exams for the dental and OHS students are ongoing. In addition, analysis of a validated survey containing Likert-style questions to quantify how the new course enhances motivation, engagement, and perceived benefits of student learning is underway. Our results indicate that additional team and case/problem-based support can improve academic performance for students hoping to gain admission to Dental School.

No funding for this project.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Unraveling the Interplay of p21, Autophagy, and Mitophagy in Mitigating Skeletal Muscle Dysfunction during Aging and Obesity
Authors: Kim Siyun , Noh Sung Gi , Wang Lichao , Xu Ming , Kwon Oh Sung
Published: May 2024

Introduction: The accumulation of senescent cells accelerates aging, a process further exacerbated by obesity. The decline of muscle function is a hallmark of this progression due to muscle atrophy stemming from dysregulated autophagy and mitochondrial function in skeletal muscles. p21 is one of the major regulators, which accumulates in tissues with aging and obesity. Previous studies have demonstrated that the elimination of p21-highly-expressing ( p21high) cells improves muscle function. However, the connection between p21 and its influence on muscle function remains unclear. One possible explanation is associated with alternations in autophagy and mitophagy through mitochondria dysfunction and increased reactive oxygen species. Therefore, this study investigated the link between autophagy, mitophagy, and p21 in the context of aging and obesity. Methods: Four 18-month-old male p21-Cre/+; +/+ (P) and p21-Cre/+; DTA/+ (PD) mice, fed by high-fat diet for 15 months were administered with tamoxifen for twice. We previously observed the P group with accumulation of p21high cells, which were effectively eliminated in PD group. Soleus muscles were collected for subsequent immunoblotting analysis, employing primary antibodies targeting key proteins involved in autophagy and mitophagy cellular processes. Results: Our study elucidates dynamic changes driven by eliminating p21high cells in autophagy and mitophagy marker levels within the soleus muscles of mice exposed to a high-fat diet for 15 months. There was no significant difference in the body weight of P and PD mice (65.1±2.58 g vs. 64.3±2.22 g). In P mice, an increase in the upstream autophagy initiator, Beclin1, was observed, along with elevated levels of ATG4A, ATG7, and the ATG12-ATG5 complex, indicating elongation of autophagosome formation. Despite increased autophagosome marker p62, the LC3-II/LC3-I ratio remained unchanged. Lysosomal markers, LAMP1 and LAMP2, were both elevated in P mice. Conversely, PD mice exhibited heightened mitochondrial damage elimination markers, Parkin, VDAC1, and DRP1. Although PINK1 levels were not significantly changed, they showed an increasing trend. Conclusion: Our results suggest that eliminating p21high cells may be the potential therapeutic approach to enhance skeletal muscle function in the context of obesity and aging, possibly through autophagy and mitophagy.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.