bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of ovariectomy on catecholamine synthesis in rats exposed to dexamethasone in utero
Authors: Martinez Monique , Madhavpeddi Lakshmi , Alvarez Jared , Hale Taben
Published: May 2023

Previous studies have demonstrated that when pregnant rat dams are administered the synthetic glucocorticoid, dexamethasone (DEX), in late gestation, the female offspring exhibit altered autonomic regulation compared to females exposed to vehicle (Veh). This altered autonomic regulation is characterized by a reduced high frequency power component of heart rate variability and increased stress-responsive blood pressure and heart rate. Moreover, we have recently determined that heart rate in DEX-exposed females shows a greater reliance on sympathetic nervous system at rest and during stress, as compared to Veh-exposed rats. The purpose of the current project was to further investigate the effect of in-utero DEX exposure and gonadal steroid hormones on local autonomic regulation in adult female offspring. Specifically, we measured left ventricular and adrenal expression of tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and catechol-o-methyltransferase (COMT) as indicators of sympathetic regulation. Pregnant dams were administered DEX (0.4mg/kg per day) or Veh on gestation days 18-21. At 9 weeks, the female offspring underwent an OVX or Sham surgery. At 12 weeks, these rats were euthanized on diestrus and the left ventricles and adrenals were processed and subjected to western blot analysis to quantify protein expression of interest. TH expression tended to be reduced in left ventricle (0.57-fold, p>0.05) yet increased (1.5-fold, p>0.05) in adrenal gland in rats prenatally exposed to DEX. In both cases, there was no difference in expression of TH between vehicle and DEX rats following OVX. DBH expression was not different in adrenal gland, regardless of prenatal exposure or OVX. However, in the left ventricle, OVX resulted in an overall reduction in DBH expression that reached statistical significance in the DEX OVX rats (-50%, p=0.0079 vs Veh Sham). COMT expression was not influenced by prenatal DEX or OVX in the left ventricle. Taken together, the findings reveal a differential regulation of catecholamine synthesis in adrenal gland as compared to the left ventricle of the heart. The findings suggest that local regulation of catecholamine synthesis does not underlie our previous findings of increased sympathetic nervous system activation of females exposed to DEX in utero. Additional investigation of cardiac beta-adrenergic receptor expression, as well measures of the central autonomic nervous system circuitry, may provide further insight into the sex-dependent impact of DEX and gonadal hormones on local autonomic regulation.

NIH U54 MH118919, University of Arizona Clinical Translational Sciences, Maximizing Student Development Graduate Access Fellowship

This is the full abstract presented at the American Physiology Summit 2023 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.
Dynamic Regulation of Order Lipid Meso-domains in the Capillary Endothelial Cell Membrane
Authors: Franco Cristian , Gonzales Albert
Published: May 2023

The structure and function of ion channels are sensitive to direct interactions with lipids of the membrane and to the biophysical properties of the membrane microenvironment, such that membrane fluidity, lateral pressure profile, and thickness can modulate the channels. Cholesterol plays a significant role in regulating membrane fluidity and is capable of phase separation where cholesterol will spontaneously separate into its own domain, which is partially responsible for developing two distinct domains within the membrane. These ordered domains are regions of high cholesterol and low fluidity, and the disordered domains are regions of low cholesterol and high fluidity. Here we examine and provide evidence of the presence of ordered cholesterol membrane domains in capillary endothelial cells. We will test the hypothesis that capillary endothelial cell ordered domains function as a signaling hub for different phospholipids regulating ion channel function. Using the isolated retinal vasculature, confocal microscopy, and fluorescent Bodipy-cholesterol, a marker of ordered lipid domains, we observed large regions approximately 2.3± 0.9 μm long of cholesterol ordered meso-domains within capillary endothelial cells and not the feeding arteriole. To determine the dynamic nature of these meso-domains, we used membrane-disordering drugs to disrupt the organization of membrane lipids. The ordered meso-domains display dynamic membrane disordering by ethanol and can re-cluster into the large ordered meso-domains. In addition, we observed that the critical signaling phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) co-localized with the ordered meso-domains. To determine the cooperativity between these lipid molecules, we examined the effects of ethanol-dependent disordering of cholesterol on the membrane localization of PIP2. In addition, we examined the effects of PIP2 depletion with the G-protein couple receptor agonist, U46619, on the disordered state of the cholesterol meso-domains. These data suggest that ordered meso-domains might play a role as a signaling hub affecting the membrane fluidity and bioavailability of signaling lipids modulating ion channel function in capillary endothelial cell.

This is the full abstract presented at the American Physiology Summit 2023 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.
Super-resolution ultrasound imaging -- creating 3D in vivo images of the renal microvasculature
Authors: Sørensen Charlotte Mehlin , Soegaard Stinne , Andersen Sofie , Taghavi Iman , Nielsen Michael , Jensen Jørgen
Published: May 2023

Aim: Our overall aim is to create 3D in vivo microvascular imaging of the renal vasculature in healthy and diabetic rats in real time. Methods-1: Super-resolution ultrasound imaging (SRUS) using intravascular microbubbles (MBs) can generate in vivo images of the renal microcirculation. Spatially separated MBs are followed over numerous image frames to create anatomical vascular images showing MB direction and velocity. Presently, images with a resolution of 50 μm are obtainable. Results-1: As diabetes mellitus is associated with micro- and macrovascular diseases also affecting the kidneys we used SRUS on Zucker Diabetic Fat rats (ZDF) aged 12-, 20- and 40-weeks. We show a significant decrease in vascular density in the cortex at week 12 before onset of proteinuria when compared to age-matched lean Zucker rats. At week 20 vascular density decreased in the outer medulla and inner medulla. No significant changes were found in vascular tortuosity. However, the SRUS images are collected over several minutes, and are challenged by tissue motion and the lack of real-time imaging. The fragile MBs limit emission pressure and thus scan depth. Hypothesis: We hypothesize that tracking erythrocytes instead of MBs will reduce these obstacles and make the method non-invasive. Resolution and scan depth will increase and scan time will shorten. This will allow an easy transition into the clinic. Results-2: Using this innovative method, we have generated images of healthy rat kidneys. Within 24 seconds, we can create an image of the renal vasculature showing the vasa recta (the capillary network penetrating the medulla) and the arcuate and cortical radial arteries. μCT scans have verified the structure of the vascular tree. However, even at these short scan times, there is considerable tissue motion from heart-beat, respiration etc. moving the image out of plane. To clearly image the true microcirculation, 3D imaging is needed. We have recently obtained this amazing step and made a 3D in vivo scan of a healthy rat kidney.

The project is funded by an ERC Synergy Grant SURE, project no. 854796.

This is the full abstract presented at the American Physiology Summit 2023 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.
Decentering and baroreflex sensitivity in adults with elevated blood pressure
Authors: Bishop Reagan , Thivierge Grant , Larson Robert , Durocher John
Published: May 2023

Previous studies have linked the ability to decenter, a non-judgmental view of emotions, with lower arterial stiffness and better nocturnal blood pressure dipping in adults. It is unknown however if autonomic regulation of blood pressure is linked to decentering. Therefore, the purpose of this study was to determine if decentering ability is related to cardiovagal or sympathetic baroreflex sensitivity. Thirty-three adults (age 25±6 years; BMI 25±3 kg/m2) with resting blood pressure ≥120/80 mmHg volunteered for this study. All participants had a BMI <30 kg/m2, and had no history of smoking, diabetes, or prescriptions for blood pressure or cardiac function. Participants completed an 11-item experiences questionnaire to evaluate decentering, and then were equipped for a supine autonomic evaluation. The autonomic evaluation included continuous recording of heart rate via 3-lead ECG, muscle sympathetic nerve activity (MSNA) via microneurography, and beat-to-beat blood pressure via finger photoplethysmography. Cardiovagal baroreflex sensitivity (n=33) included estimation of vagal activation by evaluating up-up relationships between systolic arterial pressure (SAP) and R-R intervals of the ECG. Vagal withdrawal was also estimated via the down-down relationships between SAP and R-R intervals. Spontaneous sympathetic baroreflex sensitivity (n=26) was evaluated by evaluating the relationship between changes in diastolic arterial pressure (DAP) in 3 mmHg bins vs. changes in MSNA burst incidence (i.e., bursts / 100 heart beats). Results from 2-tailed Pearson correlation analyses revealed that there was not a relationship between decentering and vagal activation (r=-0.07; p=0.71) or between decentering and vagal withdrawal (r=-0.28; p=0.12). Likewise, there was no relationship between decentering and sympathetic baroreflex sensitivity (r=0.10; p=0.64). Our findings suggest that there is not a clear link between decentering and autonomic regulation of blood pressure as estimated through both cardiovagal and baroreflex sensitivity.

NIH (1R15HL140596-01); Nils K. Nelson Endowment Fund

This is the full abstract presented at the American Physiology Summit 2023 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 sodium diet and intestinal permeability in young, healthy adults
Authors: Kaseman Kathryn , Smiljanec Katarina , Lobene Andrea , Axler Michael , Lennon Shannon
Published: May 2023

High sodium diets (HSD) have been shown to both increase blood pressure (BP) and lead to gut dysbiosis in adults. Gut dysbiosis can increase intestinal permeability (IP), allowing for translocation of bacteria and their products into the systemic circulation. There, bacteria and their products are recognized by the immune system and can activate pro-inflammatory pathways such as TH17 in a dose dependent manner. HSD has been shown to activate those pathways and increase BP in men. However, the effect of a HSD on IP has not been explored as a potential mechanism of HSD induced BP changes. The objective of this research was to investigate if a HSD can increase IP and inflammatory markers. We hypothesized that plasma concentrations of two common biomarkers of IP, zonulin and LPS binding protein (LBP), and proinflammatory TH17 lymphocytes would increase, while anti-inflammatory Treg lymphocytes would decrease on a HSD compared to a recommended sodium diet (RSD). Twenty-seven healthy participants (15W/12M, age 24±3 yrs, BP 112±9/65±6 mmHg) underwent a 10-day HSD (6,900mg sodium/d, supplemented by salt pills) and a 10-day RSD (2,300 mg sodium/d) intervention in randomized order. On day 9 of each intervention, participants collected urine and wore an ambulatory BP monitor for 24hr. Blood was collected to measure plasma zonulin and LBP by ELISA. TH17 and Treg populations were characterized from PBMCs by flow cytometry. Paired t-tests were used to compare variables on day 9 between diets. Pearson correlations were used to assess the relation between markers of IP and BP. Twenty-four-hour sodium excretion was increased on the HSD (RSD: 135±57 mmol/24h, HSD: 290±68 mmol/24h, p<0.0001). Mean 24-hr SBP (RSD: 116±10, HSD: 117±11 p=0.70) and DBP (RSD: 66±6 mmHg, HSD: 66±5 mmHg, p=0.84) were not different between diets. Plasma zonulin concentrations (RSD: 2.6±1.6 ng/ml, HSD: 2.6±1.5 ng/ml p=0.88) and LBP concentrations (RSD: 3.2±1.7 μg/ml, HSD: 3.2±1.8 μg/ml, p=0.72) were not different between diets. The TH17/Treg ratio was not different between diets (RSD: 0.54±0.51, HSD: 0.41±0.38; p=0.21) however the ratio was inversely associated with zonulin (r=-0.57 p=0.04), and LBP (r=-0.61; p=0.012) on HSD when controlling for age and sex but not on RSD (all p>0.05). These data suggest that 10 days of a HSD did not change IP, BP or T lymphocyte populations in young, healthy individuals. However, the TH17/Treg ratio was associated with zonulin and LBP suggesting that the immune system may respond to changes in IP. Future research is needed to determine whether a HSD can affect IP and inflammation in salt sensitive populations.

NIH Grants R01 HL145055 and P20GM113125

This is the full abstract presented at the American Physiology Summit 2023 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.
Right ventricular function in hearts of a mouse model of Duchenne muscular dystrophy following increased ventricular load
Authors: Lambert Michelle , Behrmann Andrew , Nourian Zahra , Nyanyo Keith , Hanft Laurin , Krenz Maike , McDonald Kerry , Domeier Timothy
Published: May 2023

Duchenne muscular dystrophy (DMD) is an X-linked recessive myopathy caused by mutations in the gene encoding dystrophin. Dystrophin is present in striated muscle cells and stabilizes the sarcolemma to mitigate contraction-induced damage. The main cause of death in DMD is cardiopulmonary failure by age 30. Diaphragmatic weakness in DMD causes restrictive lung disease and excessive afterload on the right ventricle (RV). Thus, RV dysfunction in DMD patients is typically observed early in disease progression. The objective of this study was to investigate ex vivo RV function in a mouse model of muscular dystrophy and test the hypothesis that RV function is impaired following a sustained increase in ventricular preload and afterload. Right-ventricular pressure development (Pdev) and rate of pressure decay (dP/dtMin) were monitored in isolated perfused hearts of 2-6 month normal (C57BL/6, n=5) and dystrophic (mdx4CV, n=5) male mice. Measurements were obtained under unloaded conditions and during right-ventricular load challenge (10 mmHg preload; 20 mmHg afterload). Coronary effluent lactate dehydrogenase (LDH) levels were measured following 30 minutes of sustained load challenge to assess cardiac damage. Our results show dystrophic hearts exhibited greater RV Pdev than normal hearts under unloaded conditions (24±2 mmHg mdx4CV vs 15±2 mmHg C57BL/6, P=0.015). In response to load challenge, Pdev increased (P<0.05) in both groups, but it was similar between dystrophic and normal hearts (32±1 mmHg mdx4CV vs 33±3 mmHg C57BL/6). Rate of pressure decay was similar between dystrophic and normal hearts under both conditions. Levels of LDH following load challenge were higher (P<0.05) in dystrophic versus normal hearts. In conclusion, in the absence of ventricular load RV contractile function was enhanced in dystrophic hearts. With RV load both dystrophic and normal hearts exhibited similar contractile function, yet sustained load challenge increased cellular damage in dystrophic versus normal hearts.

National Institutes of Health, University of Missouri School of Medicine, University of Missouri System

This is the full abstract presented at the American Physiology Summit 2023 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.
Increased nitric oxide-soluble guanylyl cyclase signaling improves endurance capacity and contracting skeletal muscle oxygenation in healthy female rats
Authors: Weber Ramona , Schulze Kiana , Hageman K. Sue , Musch Timothy , Poole David
Published: May 2023

Introduction: During exercise skeletal muscle blood flow and O2 delivery (Q̇O2) as well as mitochondrial oxygen uptake (V̇O2) are regulated, in part, by nitric oxide (NO)-soluble guanylyl cyclase (sGC) signaling. Exercise-induced metabolic adaptations within skeletal muscle lead to a higher Q̇O2-V̇O2 ratio (measured as increased interstitial partial pressure of O2, PO2 is), which is driven partly via increases in NO bioavailability. The sGC activator BAY 60-2770 augments downstream NO signaling by targeting the heme-free sGC enzyme, which constitutes 20-60% of sGC in healthy smooth muscle cells. We tested the hypotheses that sGC activator BAY 60-2770 administration would increase skeletal muscle oxygenation (spinotrapezius PO2 is) and enhance endurance capacity. Methods: Healthy female Sprague-Dawley rats (n=6) performed a baseline time-to-exhaustion (TTE) exercise protocol and were then randomly assigned to vehicle (V) or sGC activator (sGC) groups. sGC rats were administered 0.3 mg/kg b.i.d for five days via oral gavage. Following the dosing regimen, repeated TTE testing determined running endurance capacity on a motor-driven treadmill. On a subsequent day, the PO2 is at rest and its temporal profile following the onset of 1 Hz twitch contractions in the spinotrapezius muscle were measured using phosphorescence quenching under pentobarbital anesthesia. Results: sGC rats evidenced a 34% increase in TTE (p < 0.05) compared to V rats. There was no statistical difference in arterial blood gases and pH or heart rate and mean arterial pressure between groups during anesthesia (p > 0.05). Phosphorescence quenching revealed a significant increase in PO2 is at rest and during contractions (p < 0.05) in sGC versus V rats. Conclusions: These findings demonstrate that increasing downstream NO signaling via augmented sGC activity has the potential to improve endurance exercise capacity and skeletal muscle oxygenation at rest and during contractions in female rats. Further studies will focus on increasing the sample size to assess the robustness of these observations and investigate whether there is any pertinent sexual dimorphism in sGC signaling. We will also resolve corollary molecular signaling pathways that might be upregulated by chronic sGC activation which may positively impact skeletal muscle contractile function and exercise performance.

This work was supported, in part, by the National Institute of Aging (1 R15 AG 078060) and a SMILE Award from Kansas State College of Veterinary Medicine.

This is the full abstract presented at the American Physiology Summit 2023 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.
Big data and genomics of Insulin to expand our knowledge
Authors: Cook Taylor , Prokop Jeremy
Published: May 2023

Physiology research must be guided moving forward by our significant investments represented by deposited data. We hypothesize that integrating these resources, namely our investments into genomics, makes it possible to discover many aspects of well-studied physiological pathways. Within this work, we build a genomics integration for the Insulin gene/protein, which serves as an example of data integrations that can be applied to any physiological system. The INS gene region has 2,076 unique variants from population genetics of hundreds of thousands of individuals (gnomAD, ClinVar, Geno2MP, Avada, dbSNP). Several variants are found near the transcriptional start site, enhancers, and following the INS transcripts that might influence the readthrough fusion-transcript INS- IGF2. This INS- IGF2 transcript splice site is confirmed within hundreds of pancreas RNAseq samples, lacks drift based on human genome sequencing, and has a possible elevated expression due to viral regulation within the pancreas/liver. Moreover, a rare, poorly characterized African-specific variant of INS-IGF2 results in a loss of the stop codon. INS transcript UTR variants rs689 and rs3842753, highly associated with Type 1 Diabetes, are found in hundreds of pancreas RNAseq datasets with an elevation of the 3’UTR alternatively spliced INS transcript. Finally, by combining literature, evolutionary profiling, and structural biology, we map rare missense variants involved in type-1 diabetes, type-2 diabetes, and monogenic/neonatal diabetes that influence Pre-Pro-Insulin translation, Pro-Insulin processing, dimer/hexamer secretory storage, receptor activation, and C-peptide detection for quasi-Insulin blood measurements. Finally, through these complex Insulin pathways and multiple animal model species, we highlight the many genes involved and how environmental factors such as cellular stress may interact with genetics to increase the prevalence of diabetes. Overall, our data integration strategy yields a platform for merging our investments into animal physiological model systems, human clinical genomics, and growing investments into genome sequencing to highlight the many exciting future research needs of physiological pathways.

This research was funded by the Gerber Foundation (to JWP), National Institutes of Health (K01ES025435 to JWP), and Michigan State University.

This is the full abstract presented at the American Physiology Summit 2023 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.
Objective cardiovascular autonomic abnormalities persist over time in patients with Post-Acute Sequelae of COVID-19 (PASC)
Authors: Hira Rashmin , Siddiqui Tanya , Baker Jacquie , Bourne Kate , Ranada Shaun , Soroush Ateyeh , Karalasingham Kavithra , Ahmad Hyeqa , Morillo Carlos , Sheldon Robert , Raj Satish
Published: May 2023

BACKGROUND: The novel coronavirus (SARS-CoV-2) has negatively impacted the health and economy of the world. While most patients recover, many are suffering from symptoms several months after resolution of the acute illness (“Post-Acute Sequalae of COVID-19” [PASC]). Symptoms include fatigue, light-headedness, and tachycardia/palpitations, similar to symptoms of cardiovascular autonomic disorders such as Postural Orthostatic Tachycardia Syndrome (POTS), Initial Orthostatic Hypotension (IOH), Orthostatic Hypotension (OH), and Inappropriate Sinus Tachycardia (IST). We have previously shown a high prevalence of autonomic abnormalities among PASC patients. We currently do not know if these autonomic abnormalities are chronic and persist in PASC patients over time. OBJECTIVE: We aimed to determine if the autonomic abnormalities seen in patients after COVID-19 infection are persistent or transient, by comparing hemodynamic criterion between baseline and follow-up visits. We hypothesize that patients will recover, and abnormalities will not persist between the visits. METHODS: PASC patients (n=64; F=51; 46±12y) completed baseline visits 411±133 days after their initial COVID-19 infection and follow-up visits 97±9 days later. Patients underwent autonomic function testing with beat-to-beat hemodynamics during 10min supine rest followed by a 10min active stand. Patients were evaluated for hemodynamic criterion for POTS (­­­­↑HR≥30bpm within 10min), IOH (transient ↓SBP≥40mmHg within 15s), OH (↓SBP≥20mmHg within 3min), and IST (supine HR>100bpm). Categorical data were analyzed with a McNemar’s test. RESULTS: 19 (30%) participants met POTS criterion at baseline vs. 15 (23%) at follow-up (p=0.1). 43 (67%) participants met IOH criterion at baseline vs. 37 (58%) at follow-up (p=0.08). The OH criterion was seen in 2 (3.1%) vs 5 (7.8%) patients (p=0.2) and IST was seen in 1 patient at both visits (1.6%). Overall, 48 (75%) patients met the hemodynamic criterion for at least one autonomic disorder at baseline and 43 (67%) patients met at least one criterion at follow-up (p=0.09). CONCLUSION: Many patients with PASC have evidence of cardiovascular autonomic abnormalities, most commonly IOH, followed by POTS. The prevalence of these abnormalities does not decrease over time. These findings suggest patients with PASC are not recovering from autonomic complications due to their COVID-19 infections. Treatment and management strategies for autonomic abnormalities are needed to improve the quality of life for these patients.

Funding: Canadian Institutes of Health Research (CIHR)

This is the full abstract presented at the American Physiology Summit 2023 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.
Osteopontin Expression is Upregulated in Gonadal Adipose Tissue During Early Menopause Stage in Female Mice
Authors: Hossain Mehorunnesa , Maddie Nicole , Carrillo-Sepulveda Maria
Published: May 2023

Background: Menopausal women are at high risk of developing atherosclerosis. Reduced ovarian hormone production is a key feature of menopause, and it often leads to increased visceral adiposity and atherosclerosis. Osteopontin (OPN) is an inflammatory cytokine found in high levels in menopausal women, and in human atherosclerotic plaque. While recent studies report that macrophages in male epididymal white adipose tissue are able to produce OPN, less is known about the gonadal white adipose tissue (gWAT) in females. We hypothesize that OPN protein expression is up-regulated in gWAT in early stages of menopause, conferring gWAT as a source of OPN.Methods: To address our hypothesis, a bilateral ovariectomy in a surgical menopausal murine model was utilized. Twelve-week-old female C57BL/6 sexually mature mice were randomized into two experimental groups: Sham group (n=5) whose ovaries remained intact, and OVX group (n=6), who underwent ovariectomies, and were observed for four weeks therafter. At terminal experiments, gonadal white adipose tissue (gWAT) was collected for biochemical analysis. Results: As expected, OVX mice exhibited increased body weights (24.07 ± 0.85 g vs 21.06 ± 0.38 g controls, p<0.05) and increased gWAT mass (13.69 ± 1.421 mg/g vs 9.58 ± 0.55 mg/g control, p<0.05), indicating that early decline in female hormones is able to promote adiposity. Strikingly, greater OPN expression (2.57 ± 0.50 a.u vs. 0.76 ± 0.13 a.u sham group, n=3, p<0.05) was observed in the gWAT from the OVX group. Conclusion: Our results indicate that OPN expression in gWAT is increased during early stages of menopausal status, and suggest that gWAT could be a potential source of high levels of OPN in menopause. Our data suggest that female gWAT is not only an expanded fat depot but a metabolically active tissue contributing to an inflammatory state in menopause by an increased production of circulating cytokines such as OPN, which can ultimately contribute to inflammatory processes, including atherosclerosis.

Funding: Diabetes Action to Maria Alicia Carrillo Sepulveda

This is the full abstract presented at the American Physiology Summit 2023 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.
Sodium channel protein alpha subunit genomics: building an integrated knowledgebase to translate between family members
Authors: Zieba Jacob , Wilstermann Amy , Hernandez Angel , Prokop Jeremy
Published: May 2023

The sodium channel alpha proteins consist of ten homologous human proteins (SCN1A, SCN2A, SCN3A, SCN4A, SCN5A, SCN7A, SCN8A, SCN9A, SCN10A, SCN11A), many involved in various human physiological pathways and clinical disorders/syndromes. Many human variants connected to these genes remain uncertain for human disease. To better support the understanding of challenging human variants, we have built an ortholog database of the alpha subunit proteins for the sodium channel. We combined 1,680 vertebrate species sequences of family members, protein modeling, molecular dynamic simulation of lipid embedded protein, screening of human variants (gnomAD, ClinVar, Geno2MP), and analysis of a large number of human RNAseq and single-cell RNA-seq to understand the function of each amino acid in the human proteins and how the amino acids are conserved across family members to contribute to sodium channel functions within diverse cells of human. There are 610 amino acids conserved across the alpha subunit family, representing the most conserved amino acids for each member. These amino acids drive the structural fold, membrane interactions, and channel opening. A cluster of amino acids is conserved between a subset of family members that defines subclusters of alpha subunit proteins. Expression analysis of each member reveals clusters of members co-expressed in various cells, where heart and brain datasets show the specificity of cell types that contribute to genotype-to-phenotype associations of each member. Further, to support variant characterizations, the ortholog alignment data provides a unique ability to discover loss vs. gain of function variants found between members, allowing for known pathogenic variants of one member to aid in the characterization of another member's uncertain variants. For example, a clinical variant of SCN8A linked to seizures was supported as loss-of-function through variants within SCN1A (epilepsy), SCN2A (seizures), SCN4A (Familial hyperkalemic periodic paralysis), and SCN5A (Brugada syndrome). Overall, we show an exciting and promising new tool for ortholog genomic mapping that can support clinical variant insights into physiological outcomes (genotype-to-phenotype relationship), which should be applied to other cellular ion channels and transporters.

This research was funded by the Gerber Foundation (to JWP), National Institutes of Health (K01ES025435 to JWP), and Michigan State University.

This is the full abstract presented at the American Physiology Summit 2023 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.
Transgenerational effects of opioids on cardiovascular outcomes of the rat offspring
Authors: Ahmed Nermin , LORIA ANALIA
Published: May 2023

Opioid use disorder (OUD) is one of the greatest public health threats in the US. In 2020, more than 69,000 Americans died of a drug overdose involving opioids. Starting in 2014, an alarming third wave is on the rise now caused by synthetic opioids, specifically illicit fentanyl (FEN). OUD among pregnant women is an understudied area related to the opioid epidemic, showing a 5-fold increase incidence of neonatal opioid withdrawal syndrome (NOWS). Currently, the only two FDA-approved medications indicated for medication assisted treatment (MAT) during pregnancy are methadone and buprenorphine. While some general guidelines have been established to place pregnant woman on MAT, the misuse of fentanyl has challenged the current pharmacotherapies, urging for the characterization of pre-clinical models.The aim of this study was to investigate the trasngenerational effects of opioids on the cardiovascular system. We subjected female rats to opioids exposure during pregnancy. We investigated: 1) In the newborns, the morphometrics and withdrawal symptoms; 2) In the adult offspring, the locomotor sensitization 3) The short and long-term plasma endogenous opioids peptides status, and 4) the transcriptomics of brain areas involved in the neural interface between motivation and action.We found that female and male neonates from opioids-treated dams are smaller through the lifespan compared to VEH-exposed counterparts (n=6, p<0.05). Also, adult offspring exposed to MOR in utero displayed sympathetic activation and increased cardiometabolic risk factors along with increased locomotor sensitization to MOR (n=4, p<0.05). In addition, we performed RNAseq analysis of the perivascular nucleolus of the hypothalamus in MOR-exposed offspring, showing increased FOSb expression (n=3 per group). ΔFosB, encoded by the fosB gene, is induced in the brain's reward regions by chronic exposure drugs of abuse and mediates sensitized responses to drug exposure.We also found that rat neonates exposed to opiods showed behavioral NOWS-like symptoms. Importantly, we found that the prenatal exposure to opioids induces a long-term dysregulation of the endogenous opioids peptides (EOP) pro-enkephalin and pro-dynorphin.Both endogenous and exogenous opioids can bind to opioid receptors, which are G-protein coupled receptors (GPCRs) that can dimerize and affect the function of other GPCRs with important neurobehavioral functions.This study provides insights regarding how opioids could affect the programming of the mechanisms regulating blood pressure control later in life.

This is the full abstract presented at the American Physiology Summit 2023 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.
MLN alters SERCA1a and SERCA2a kinetics but does not alter the apparent coupling ratio
Authors: Juracic Emma Sara , Brahmbhatt Aditya , Tupling A. Russell
Published: May 2023

The sarco(endo)plasmic reticulum Ca2+-ATPases (SERCAs) are responsible for inducing muscle relaxation and are integral to the maintenance of intracellular calcium (Ca2+) homeostasis. As such, their activity is modulated by multiple regulatory proteins. Myoregulin (MLN) is a newly discovered protein inhibitor of SERCAs that physically interacts with the pump to regulate Ca2+-handling in muscle. While MLN has emerged as a key regulator of Ca2+ homeostasis and muscle contractility, it is unknown whether MLN can uncouple Ca2+ transport from ATP hydrolysis by SERCAs and in doing so, alter SERCAs’ apparent coupling ratio. To that end, HEK-293 cells were co-transfected with cDNA encoding SERCA1a alone or with SERCA1a and MLN and SERCA2a alone or with SERCA2a and MLN. Both Ca2+ uptake and Ca2+-ATPase activity were measured on crude cell homogenate prepared from the transfected cells. Ca2+-dependent SERCA activity was assessed over Ca2+ concentrations ranging from pCa 6.85 to 4.80 in presence and absence of the Ca2+ ionophore A23187 using a spectrophotometric plate reader assay. SERCA-mediated Ca2+ uptake was measured in the presence and absence of the precipitating anion, oxalate, using the fluorescent dye Indo-1 and a fluorometer. SERCA coupling ratio was calculated by dividing Ca2+ uptake by Ca2+-ATPase rates across different pCa values. In both the presence (p < 0.05) and absence of ionophore (p < 0.05), MLN significantly depressed the maximal rate of ATP consumption (VMAX) and SERCA’s Ca2+ affinity, with this effect being more pronounced in the presence of ionophore. Similarly, MLN significantly reduced SERCA Ca2+ uptake in both conditions, with a greater effect in the presence of oxalate. The ability of MLN to reduce VMAX and impede Ca2+ uptake was greater for SERCA1a compared to SERCA2a. These results indicate that MLN does not affect the Ca2+/ATP coupling ratio of SERCA1a and SERCA2a pumps at maximal (presence of ionophore/oxalate) and physiological (absence of ionophore/oxalate) conditions.

NSERC

This is the full abstract presented at the American Physiology Summit 2023 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.
Bile acids altered by high fat feeding and oligofructose supplementation impact metabolic homeostasis
Authors: Meyer Rachel , Plett Rannon , Weninger Savanna , Wachsmuth Hallie , Duca Frank
Published: May 2023

The gut microbiota is recognized as a contributor to host metabolic homeostasis, as obesity and diabetes are associated with unique gut microbiome signatures. Further, strategies aimed at beneficially shifting the gut microbiome, such as prebiotic treatment, show promise in ameliorating metabolic disease; however, the mechanisms are not yet understood. A potential contribution of the gut microbiota to host metabolism is via modification of host and diet-derived metabolites. For example, bile acids, crucial to lipid digestion and absorption, are modified by gut microbes in the small intestine. Bile acids have also been identified as signaling molecules in the intestine, liver, adipose, and nervous system, playing a role in metabolic homeostasis. Despite their importance, few studies have examined the impact of bile acid signaling on mediating the metabolic benefits of prebiotics. We hypothesized that bile acid homeostasis is altered with dietary factors that shift the gut microbiome, including high fat diet (HFD) feeding and supplementation with the prebiotic fiber oligofructose (OFS), and that taurocholic acid (TCA) and glycodeoxycholic acid (GDCA) that are increased with HFD feeding and OFS supplementation, respectively, would recapitulate the metabolic effects of these diets. Therefore, we conducted an untargeted metabolomics analysis on small intestinal contents of rats fed chow, HFD, or HFD supplemented with OFS, identifying bile acid metabolism as a primary contributor to the observed between-group differences. We then quantified bile acid levels in the small intestine, portal vein, and liver of rats fed chow, HFD, or HFD supplemented with OFS, and identified several bile acids of interest that are altered with HFD or OFS supplementation, including TCA and GDCA. Because these bile acids activate the bile acid receptors, FXR and TGR5, that known to impact metabolic homeostasis, we treated HFD-fed mice with 50 mg/kg GDCA or TCA daily for 12 weeks and measured body weight, adiposity, glucose tolerance, food intake, and indirect calorimetry. We found that GDCA treatment improved glucose tolerance, decreased body weight and adiposity, and increased energy expenditure compared to controls. Further, TCA worsened glucose tolerance independent of body weight. The results of this study implicate GDCA and TCA in the beneficial and detrimental effects of OFS and HFD-feeding, respectively; however, more research is necessary to determine the mechanism underpinning the metabolic effects of GDCA and TCA treatment.

This work was supported by the NIH R01DK1804.

This is the full abstract presented at the American Physiology Summit 2023 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.
Respiratory instability in neonatal rats after exposure to gestational intermittent hypoxia
Authors: Sprenger Ryan , Marino Nicholas , Johnson Stephen , Baker Tracy , Watters Jyoti
Published: May 2023

Sleep disordered breathing (SDB) during pregnancy is a growing concern because it causes adverse outcomes for infant offspring. Recently, our lab developed a rat model of SDB during pregnancy in which pregnant dams were exposed to gestational intermittent hypoxia (GIH; 15 episodes/hr of 10.5% oxygen for 8h daily from days 10-20 of pregnancy). Control dams were exposed in parallel to gestational intermittent normoxia (GNX). We found that male (but not female) GIH offspring had increased apneas in adulthood compared to their GNX control counterparts. Thus, in this study, we tested the hypothesis that GIH would increase respiratory instability (i.e. increase the number of apneas) in neonatal male, not female, offspring. Plethysmography was performed on GIH and GNX male and female pups at postnatal (P) days 0, 10, and 15, and the number of apneas was quantified. An apnea was defined as two missed breaths (2x the average period between breaths). Preliminary data suggest that apnea frequency was sexually dimorphic and changed both with development and treatment. At P10 and P15 male GIH offspring had more apneas compared to GNX offspring (p<0.05). However, at P0, male GIH offspring (16 ± 2.4 apneas/10m) had surprisingly fewer apneas compared to GNX offspring (28 ± 1.9 apneas/10m). In female offspring in contrast, there was no difference in apnea frequency between GIH and GNX treatment at P0, but at P10 and P15 respectively, female GIH offspring (17 ± 2.8 and 9 ± 2.3 apneas/10m) had more apneas compared to their GNX counterparts (8 ± 1.2 and 2.9 ± 0.57 apneas/10m). Apnea frequency decreased with increasing age in both sexes, regardless of GIH and GNX treatment. Together, as expected, these results suggest that the increased apnea phenotype observed in the adult GIH male emerges as early as postnatal day 10. Unexpected however is the observation that female neonatal GIH offspring also experience respiratory instability in during the postnatal period despite its absence in adult female GIH offspring. Studies are currently underway to better understand the mechanisms underlying these sex differences in respiratory neural control, and the protective responses utilized by adult female GIH offspring to mitigate these respiratory deficits induced by intermittent hypoxia exposure in utero.

R01 HL142752

This is the full abstract presented at the American Physiology Summit 2023 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.
Impact of game-based learning strategies in student engagement in Health Professions education
Authors: Alarcon Fortepiani Maria
Published: May 2023

Learning is enhanced when students are involved and engaged. However, in the past years there has been an increase in student disengagement. Class attendance is decreasing and students do not complete their assignments or turn work on time. Research has demonstrated that engagement allows the student to develop higher-level critical thinking, which is essential in Health Professions. Providing opportunities for this intellectual engagement is necessary to capture the student’s attention and numerous technologies have surged to meet this goal. One of the teaching resources utilized as an engagement tool in the classroom is gamification and game-based learning strategies. In this study, we developed game based educational resources and assessed their impact in student engagement and learning in Optometry students. A total of 66 students were enrolled in a Systemic Pathology course. The course used flipped instruction and students were asked to watch pre-recorded lectures or videos on a topic before the on-site session, where they worked in groups on a case based on that topic. The game-based learning approach was used for some of the course cases and consisted in using multiple games provided by the instructor to provide a short answer for the case questions. At the end of the semester, all the students completed a feedback questionnaire. The students reported that solving cases during class, independent of the use of games, was beneficial to their learning (79%). They perceived the use of games as enjoyable (68%) and reported an improvement in their learning (69% reporting from beneficial sometimes to very often) when compared to the traditional cases without the game component. Furthermore, we compared this cohort to the same course offered the previous year with no game-based activities to determine the impact on student performance. We found that the two groups obtained similar scores in the quizzes, final exam, and course average. In conclusion, the use of game-based learning strategies increased the engagement of the students and their perception of what they learned, however, it did not seem to improve their academic performance in the course.

APS Teaching Career Enhancement Award

This is the full abstract presented at the American Physiology Summit 2023 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.
Microvascular constriction via fatty acid-mediated oxidative stress in humans
Authors: David Hannah , Holwerda Seth
Published: May 2023

Purpose: Excess plasma lipids promote oxidative stress and impair vascular function. Herein, we examined microcirculatory blood flow and tested the hypothesis that a co-infusion of a water-soluble antioxidant (ascorbic acid, AA) would attenuate reductions in retinal arteriole lumen diameter and increase resistance resulting from acutely elevated plasma lipids in healthy adults. Methods: A 20% IV fat emulsion (Intralipid) was administered for 2 hours to 8 healthy, middle-aged adults (2 men/6 women) with and without co-infusion of ascorbic acid (separate visits) in a double-blinded, crossover study design. Co-infusion of AA was administered at 0.06g/kg fat free mass in 100 ml saline at 5 mL/min over 20 min (bolus) followed by a drip infusion at 0.02 g/kg fat-free mass in 30 ml saline at 0.33 mL/min over 90 min. Retinal arteriole lumen diameter and resistance were assessed via Laser Speckle Flowgraphy at baseline and after infusion. Results: Lipid infusion significantly increase plasma fatty acid concentrations (lipid w/o AA: +36 ± 18 vs. lipid with AA: +41 ± 13 vs. μmol/L, P=0.84). AA infusion significantly increased plasma ascorbic acid concentrations (lipid w/o AA: -1 ± 7 vs. lipid with AA: +26 ± 11 μmol/L, P=0.04). A significant increase in retinal arteriole resistance was observed following lipid infusion (lipid w/o AA: +20 ± 8 %, vs. lipid with AA: +17 ± 8 %, P=0.40). In accordance, lipid infusion significantly reduced retinal arteriole lumen diameter; however, co-infusion of AA reversed the lipid-mediated decrease in retinal arteriole diameter (lipid w/o AA: -3 ± 1 % vs. lipid with AA: +3 ± 2 %, P=0.01). Conclusions: Although microvascular resistance was increased, co-infusion of the antioxidant (ascorbic acid) reversed the fatty acid-mediated reduction in arteriole lumen diameter. Therefore, these preliminary findings suggest that acute elevations in plasma fatty acids induce microvascular constriction via an oxidative stress pathway.

Funding and support: R01HL159370-01 (S.W.H.). This work was also supported by a CTSA grant from NCATS awarded to the University of Kansas for Frontiers: University of Kansas Clinical and Translational Science Institute (# UL1TR002366). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH or CTSA.

This is the full abstract presented at the American Physiology Summit 2023 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.