bluuebunny/crossref_metadata_2025 huggingface dataset:
Brachial Artery Flow-mediated Dilation Is Associated with Pulmonary Vascular Structure Among Patients with Chronic Obstructive Pulmonary Disease
Authors: D'Souza Andrew , Collins Sophie , Kuss Madeline , Kirby Miranda , Smith Benjamin , Bok Eli , Fuhr Desi
Published: May 2024

Background: Accumulating evidence indicates that pulmonary vascular insults, particularly at the level of the endothelium, may contribute to the pathogenesis of COPD. Further, the mechanism(s) underpinning pulmonary vascular remodeling/dysfunction in COPD may also contribute to systemic vascular dysfunction. Indeed, brachial artery flow-mediated dilation (FMD; an assessment of systemic vascular endothelial function) is inversely associated with emphysema among patients with COPD. However, it remains unclear whether systemic vascular function is related to pulmonary vascular structure in COPD. Thus, we aimed to evaluate the relationships between FMD and computed tomography (CT)-derived emphysema and pulmonary vascular structure in patients with mild-to-severe COPD. We hypothesized that FMD would be inversely related with CT-derived emphysema severity, and positively related with pulmonary vascular structure. Methods: 36 individuals with COPD (16 females, age: 69±6 years, FEV1: 62±19 %predicted) completed three experimental days: Day 1: Enrollment and full pulmonary function test. Day 2: Chest CT scan to quantify emphysema severity (LAA-950), total vessel volume (TVV), and the volume of vessels with a cross sectional area of <5mm2 (BV5) and between 5-10mm2 (BV5-10). Day 3: Brachial artery FMD (5-minute forearm occlusion followed by 3-minute reactive hyperemia). FMD was allometrically scaled and corrected for the prevailing shear stimulus (shear rate area under the curve). Results: FMD was not correlated with LAA-950, (r2=0.09; P=0.09); however, positive relationships were observed between FMD and TVV normalized to total lung volume (r2=0.24; P<0.01), as well as BV5-10 (r2=0.34; P<0.01). FMD was not correlated to BV5 (r2=0.09, P=0.10). Conclusion: Collectively, these preliminary data indicate that, among patients with COPD, impaired pulmonary vascular structure is associated with attenuated systemic vascular function; suggesting an interplay between the pulmonary and systemic vasculature in the pathogenesis of COPD.

Supported by the Canadian Institutes for Health Research, the Canadian Respiratory Research Network, and the “Fondation Baxter et Alma Ricard”.

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 Cytotoxic Chemotherapy and Endocrine Therapy on Hemodynamics and Oxygen Uptake During Handgrip Exercise in Patients Treated for Breast Cancer
Authors: Kofoed Jason , Borrelli Marta , Bisconti Angela Valentina , Craig Jesse , Laginestra Fabio , Colonna Sarah , Buys Saundra
Published: May 2024

Breast cancer therapies can alter skeletal muscle blood flow during exercise and decrease mitochondrial content and function. However, the impact of different therapies on the variables determining oxygen transport and utilization during submaximal exercise remain unknown. We tested the hypothesis that both chemotherapy and endocrine therapy would decrease blood flow and increase deoxygenated [hemoglobin+myoglobin] (HHb) with an unchanged oxygen uptake (VȮ2) during exercise compared to healthy controls. Participants were healthy females (CTRL; n = 5; age: 58 ± 8 years; body mass index: 25 ± 4 kg/m2) or female patients diagnosed with stage I-III breast cancer comprising three groups: 1) two to five weeks post completion of cytotoxic chemotherapy (CHEMO; n = 5; age: 55 ± 8 years; body mass index, BMI: 30 ± 4 kg/m2); 2) currently on endocrine therapy ≥5 months (ENDO; n = 9; age: 59 ± 7 years; BMI: 27 ± 6 kg/m2); and 3) completed cytotoxic chemotherapy and currently on endocrine therapy ≥5 months (CHEMO+ENDO; n = 8; age: 58 ± 6 years; BMI: 26 ± 5 kg/m2). Forearm blood flow, HHb, and estimated VȮ2 were measured during the final minute of a 3-minute intermittent isometric handgrip exercise at 3 and 6 kg. There were no group or group x intensity effects (all p<0.18) for forearm blood flow (CTRL: 260 ± 33 ml/min; CHEMO: 407 ± 96 ml/min; ENDO: 309 ± 140 ml/min; CHEMO+ENDO: 313 ± 86 ml/min), HHb (CTRL: 134 ± 58 μM; CHEMO: 73 ± 36 μM; ENDO: 118 ± 67 μM; CHEMO+ENDO: 101 ± 25 μM), or estimated VȮ2 (CTRL: 59 ± 28 ml/min; CHEMO: 48 ± 21 ml/min; ENDO: 54 ± 28 ml/min; CHEMO+ENDO: 53 ± 21 ml/min). These findings indicate that chemotherapy and endocrine therapy do not affect muscle hemodynamics and oxidative metabolism during submaximal handgrip exercise.

This study was funded, in part, by the Veterans Affairs Clinical Science Research and Career Development Award (IK2 CX002114).

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.
Mitochondrial peptides derived from exercising skeletal muscle increase oxidative stress in microvascular endothelial cells
Authors: Hansen Camilla Collin , Gudiksen Anders , Van der Stede Thibaux , Frisch Nicklas , Rol Josephine M. , Jung Jens , Hoier Birgitte
Published: May 2024

Introduction: Mitochondria-derived peptides are newly discovered small bioactive peptides thought to communicate metabolic status to other cells. Two such peptides, MOTS-c and Humanin, have been shown to have particularly strong local and systemic regulatory effects on metabolism and oxidative stress in tissues, but their effect specifically on vascular endothelial cells remains unclear. Furthermore, it has been proposed that skeletal muscle is a source of MOTS-c and humanin during exercise but this has not been directly shown. Methods: In seven healthy young males, muscle interstitial fluid was collected from microdialysis probes in the thigh muscle, blood was drawn from femoral arterial and venous catheters and thigh muscle biopsies were obtained before and after one acute bout of exercise. In addition, muscle biopsies were obtained before and after 14 days of leg exercise training. Samples were analysed for MOTS-c, Humanin protein and mRNA. To test the effect of MOTS-c on the microvasculature, human endothelial cells derived from the muscle biopsies were incubated for three days with MOTS-c and analysed for mitochondrial respiration and formation of reactive oxygen species (ROS). Furthermore, mice were injected with MOTS-c for 4-weeks to investigate the in-vivo effect of vessels and microvascular endothelial cells. Data was analyzed by linear mixed models performed with R. Results: Acute exercise resulted in an 88% and 55% ( p<0.001) increase in MOTS-c and humanin concentration, respectively, in muscle dialysate, with no effect on the femoral arterial-venous plasma concentration differences. Both MOTS-c and humanin mRNA levels increased (by 20 and 26%; p<0.05) after acute exercise and were 43% and 35% ( p<0.05) higher, respectively, after 14 days of training. A period of MOTS-c treatment of endothelial cells increased mitochondrial respiration and ROS formation by 3-fold and 5-fold, respectively ( p<0.01). Muscle derived endothelial cells from mice injected for 4-weeks presented a similar mitochondrial respiration but a 4-fold ( p<0.05) higher ROS emission. Conclusion: interstitium in response to exercise, muscle is not a likely source of these peptides in plasma. Our data from in vitro and in vivo experiments suggest that treatment with MOTS-c does not influence endothelial metabolism but leads to increased oxidative stress in microvascular endothelial cells.

The funding by Novo Nordisk Foundation (application number: 0070369) is gratefully acknowledged.

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.
Metabolic Function of Leucine-Rich Repeat Transmembrane Neuronal 4 Expressed by Hypothalamic AgRP Neurons
Authors: Kim Seungjik , Ko Jaewon , Sohn Jong-Woo
Published: May 2024

It is well known that the agouti-related peptide (AgRP)-expressing neurons of the arcuate nucleus of the hypothalamus regulate energy balance and glucose homeostasis. While it was previously shown that excitatory and inhibitory synaptic input onto the AgRP neurons influence the activity and metabolic function of AgRP neurons, little is known about the role of synaptic adhesion molecules therein. In this study, we focused on a synaptic adhesion molecule, leucine-rich repeat transmembrane neuronal 4 (LRRTM4), which is expressed by post-synaptic part of excitatory synapses to be involved in synapse formation and synaptic transmission. We generated conditional knockout mice which lacks LRRTM4 specifically in the AgRP neurons, and assessed the electrophysiological and metabolic phenotypes. Our results should provide insight how synaptic machinery of hypothalamic AgRP neurons can shape in vivo metabolic function.

This work was supported by the National Research Foundation of Korea (NRF-2022R1A2C3005613 to Jong-Woo Sohn) funded by the Korean Ministry of Science and ICT.

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.
Role of Dorsal Raphe Serotonergic Neurons in the Regulation of Sodium Appetite
Authors: Shin Yurim , Kim Seungjik , Sohn Jong-Woo
Published: May 2024

An animal with sodium deficiency develops sodium appetite which drives it to consume more sodium. A lot of studies have been performed to understand how sodium depletion may lead to the development of sodium appetite, but there are still unanswered questions. In particular, while the relationship between serotonin receptors and sodium appetite has been identified in previous studies, it is still unclear how serotonergic neurons control sodium appetite in response to sodium depletion. In this study, we focused on serotonergic neurons in the dorsal raphe nucleus (DRN) which releases more than 50% of serotonin in the brain. We found that DRN serotonergic neurons are activated in response to sodium depletion. In addition, we found evidence that angiotensin II is a key molecule herein to evoke sodium appetite in sodium depletion. Our results provide refined insight how sodium appetite develops in sodium depletion.

This work was supported by grants from Samsung Science & Technology Foundation (SSTF-BA1901-11) to Jong-Woo Sohn.

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.
Insulin and glucose tolerance assessment in guanylyl cyclase/natriuretic peptide receptor-A gene-targeted mutant mice
Authors: Neelamegam Kandasamy , Ramasamy Chandramohan , Pandey Kailash N.
Published: May 2024

Atrial natriuretic peptide (ANP), acting through guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) regulates blood pressure and cardiac homeostasis. The disruption of Npr1 (encoding NPRA) in mice exhibits hypertension and provokes renal and cardiac disorder. However, the underlying mechanisms are not yet precisely determined. The objective of this study was to determine whether Npr1 plays a role in regulating glucose homeostasis in global Npr1 gene-disrupted mice. The adult male (14-18 wks) Npr1 haplotype gene-knockout ( Npr1+/-, 1-copy), wild-type ( Npr1+/+, 2-copy), and gene-duplicated ( Npr1+ +/+ +, 4-copy) mice were fasted overnight (16 h) and given free access to water. The mice were administered with glucose both orally and intraperitoneally (2 g/kg body weight) to determine the oral glucose tolerance test (OGTT) and intraperitoneal glucose tolerance test (IPGTT). For the insulin tolerance test (ITT), mice were also fasted for 16 h and then received an ip-injection of insulin (1.0 UI/kg body weight). Blood glucose levels were determined by performing tail bleeds at 0, 15, 30, 60, 90, and 120 min using the AlphaTRAK blood glucose monitoring system. The results showed that administration of glucose resulted in a greater increases in blood glucose levels at 120 mins in 1-copy mice (OGTT: 237 ± 5 mg/dL, IPGT: 246 ± 6 mg/dL, ITT; 239 ± 7 mg/dL) than 2-copy male (OGTT: 131 ± 3 mg/dL, IPGT: 126 ± 6 mg/dL, ITT; 127 ± 6 mg/dL), respectively. The blood glucose was also significantly lower in 4-copy mice (OGTT: 113 ± 5 mg/dL, IPGT: 108 ± 7 mg/dL, ITT; 107 ± 3 mg/dL) than in 2-copy mice. Systolic blood pressure (SBP) was determined by non-invasive tail-cuff method (Visitech 2000). SBP was significantly greater in 1-copy mice (130 ± 4 mmHg) than 2-copy mice (100 ± 3 mmHg). Similarly, SBP was also significantly lower in 4-copy mice (90 ± 2) than 2-copy mice. The increase in plasma glucose levels was significantly lower in OGTT than in IPGTT. The present results suggest that decreased Npr1 gene copy number predisposes to hyperglycemia, insulin resistance, and hypertension. These results indicate that the Npr1 gene might regulate blood glucose homeostasis.

This work was supported by the NIH grant (DK133833).

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.
Evaluating Physiological and Organizational Properties of the Tight Junction ZO-1 ZU-5 Domain in MDCK Cells
Authors: Holloway Cristian , Palmer Garrett , Cooper Joshua , Eis Ainsley , King Jonathan
Published: May 2024

Zonula occludens-1 (ZO-1) is an essential TJ component contributing to junctional formation by mediating interactions between junctional proteins and the actomyosin cytoskeleton. MDCK II cells, a model epithelial cell line, with ZO-1 knocked-out (ZO-1 KO) have observable phenotypic changes such as alterations in the actin cytoskeletal organization and physiological barrier properties. This study focuses on the ZO-1-ZU5 domain by rescuing ZO-1 with full-length and a panel of ZO-1-ZU5 mutants. ZO-1-ZU-5 is known to bind cingulin and through this interaction ZO-1 adopts an extended conformation. We examined actomyosin cytoskeleton organization, ZO-1 mobility, gene expression and barrier function to determine whether the ZO-1-ZU5 mutants rescue full-length activity. We found that the ZO-1- ZU5 truncation mutant cell line rescued transepithelial electrical resistance (TER) but did not rescue tight junction distribution or the amount of total gamma-actin. We will present evaluation of additional ZU5 mutants. This study expands our understanding of how extended ZO-1 regulates the mechanical, genetic, and phenotypic properties of epithelial cells.

Trinity University Biology Summer Undergraduate Research Fellowship.

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.
Intermittent Fasting Causes Sex-Specific Effects On Metabolic Switching And Aortic Inflammation In A Mouse Model Of Diet-Induced Metabolic Syndrome
Authors: Tran Vivian , Wickramasinghe Buddhila , Jamal Abdulsatar , Hughes Tayla , Diep Henry , Dinh Quynh Nhu , Sobey Christopher G
Published: May 2024

Metabolic syndrome (MetS) is a complex multifactorial disease that increases the risk for cardiovascular disease. Despite various treatment strategies, such as restrictive caloric intake and drug therapies, MetS remains challenging to manage. Intermittent fasting (IF) has been proposed as an alternative to traditional treatment as a means of MetS management. However, the sex-specific responses to intermittent fasting during MetS are unclear. Using a mouse model of diet-induced MetS, we characterised the sex-specific effects of IF on metabolic disturbances and aortic inflammation. Six-week-old male and female C57BL/6 mice were fed either a high-fat diet (43% kcal) with high-sugar and high-salt (10% high-fructose corn syrup and 0.9% NaCl in drinking water; HFSS), or normal control diet (NCD). After 10 weeks, mice were randomly assigned to ad libitum (AL) feeding or IF (16 hours/day) for 10 weeks. Physiological parameters were measured during the diet regime and aortic inflammation was measured at endpoint using flow cytometry. HFSS feeding increased bodyweight and fasting blood glucose in both sexes ( P < 0.05), which were reversed by IF irrespective of diet or sex ( P < 0.05). IF increased fasting blood ketones in HFSS-fed females (vs. HFSS-AL females; P < 0.05), but not in HFSS males. Despite HFSS-induced MetS in both sexes, aortic proinflammatory monocytes (CD11b+Ly6CHi), patrolling monocytes (CD11b+Ly6CLo) and macrophages (CD11b+F4/80+) were increased in males mice only. IF reduced proinflammatory monocytes and macrophages in HFSS-IF males as well CD4+ and CD8+ T cells (vs. HFSS-AL males, P<0.05). In summary, IF improved HFSS-induced metabolic disturbances in both sexes, yet metabolic switching (ketosis) was only observed in females. Moreover, HFSS induced aortic inflammation in males only, highlighting the sexual dimorphisms in vascular inflammation during MetS. Our study is the first to report that intermittent fasting reduces aortic inflammation in metabolic syndrome. Further studies are underway to determine the downstream effects of aortic inflammation on end-organs such as the kidneys and liver.

National Health and Medical Research Council, Graduate Women Victoria, The Jack Brockoff Foundation.

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.
Blood Glucose Fluctuation Is Indicative of Adiposity
Authors: Apaflo Jehu , Sanders Ka'Delyn , Labadah Joshua , Narvaez Gabriel , Rocha Victoria , Villalobos Ulices , John Tomy Irene
Published: May 2024

Introduction: Continuous glucose monitoring (CGM) system is an effective tool for assessing a person’s glycemic control in real-time, in a “free living condition”. Poor glycemic control is strongly linked to cardiovascular disease, obesity, and the pernicious deposition of fat in the abdominal region. Emerging data show that surges in glucose levels after a meal (postprandial glucose excursions) are more tightly linked to cardiovascular disease, insulin resistance, and diabetic complications than the traditional clinical measure of glycemic control using glycated hemoglobin (HbA1c). Therefore, the purpose of this study is to determine if daily glycemic variability as measured by CGM is an indicator of total and regional body fat distribution and how CGM compares with HbA1c measurements. Methods: Twenty-seven volunteers participated in the study (Male: 11, Female: 16, Age: 32.15 ± 14.55 years, BMI: 28.43 ± 7.30 kg/m2). Total body and regional fat distribution (android, gynoid, android/gynoid) were determined using dual-energy x-ray absorptiometry. Fasting blood glucose and glycated hemoglobin (HbA1c) were measured from collected blood samples. Glycemic variability was measured by CGM attached to the abdomen. Results: CGM glycemic variability was positively correlated with total body fat% (r= 0.4278; p= 0.0329), android fat% (r= 0.5313; p= 0.0063), and android/gynoid ratio (r= 0.5981; p= 0.0016). HbA1c was only positively correlated with android/ gynoid ratio (r= 0.5534; p= 0.0041). Conclusion: Higher blood glucose variability/fluctuation measured by CGM was associated with greater body fat, android fat, android/gynoid fat ratio, which are indicators of cardiovascular disease risks. Blood glucose fluctuation monitoring should be considered in blood glucose management.

This study was funded by The University of Texas, El Paso Dodson Fund and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH) - R01DK132430.

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.
Comparative Study of Men and Knock-in Mice Expressing Red Cell Glycophorin B-A-B hybrid Protein Identifies Physiological Functions of SLC4A1 (band 3)
Authors: Hsu Kate , Chen Li-Yang , Chen Pin-Lung
Published: May 2024

GP.Mur is a common Southeast Asian red blood cell (RBC) type, with 4.7% prevalence in Taiwan (compared to 5.8% AB blood type). In people with the GP.Mur (glycophorin B-A-B hybrid) type, their expression of Cl−/HCO3− anion exchanger-1 (AE1; SLC4A1; band 3) on the RBC membrane is increased. Glycophorin A, as well as this glycophorin B-A-B variant, are chaperone proteins that promote SLC4A1 folding and protein formation by 10% or more. Healthy people with the GP.Mur blood type exhibit two unique physiological features: (1) slightly higher blood pressure, and (2) more effcient CO2 excretion. Human and mouse lacking SLC4A1 cannot survive postnatally. As the physiological impacts and mechanisms of SLC4A1 are unclear, we created a knock-in mouse model of human GYP.Mur. To verify whether these physiological features could indeed be the direct consequences of GYP.Mur expression, we tested the knock-in mice by (1) blood pressure measurements with antihypertensive drug challenges, and (2) whole-body plethysmorgraphy (WBP)-respiration measurements. We found that GYP.Mur knock-in mice also expressed more SLC4A1 on the RBC membrane. The knock-in mice exhibited significantly higher mean arterial pressure (MAP) than age-matched control C57BL/6J mice, with differential antihypertensive sensitivities. In WBP measurements on freely-moving mice, GYP.Mur knock-in and the control mice also showed differential respiratory patterns, which were diminished with acetazolamide pretreatments. Thus, GYP.Mur knock-in mice recapitulates the major phenotypes of people carrying the GP.Mur blood type.

Taiwan Ministry of Science & Technology (MOST 108-2628-B-195-001; 109-2628-B-195-001; 110-2628-B-195-001); Taiwan MacKay Memorial Hospital.

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 In Vitro Effect of Kynurenine Metabolites on Cell morphology, Cell cycle progression and the Induction of Apoptosis in Tumour Endothelioma Cells
Authors: Tatchum Sandra , Joubert Annie , Serem June , Bipath Priyesh , Nyakudya Trevor , Hlophe Yvette
Published: May 2024

Background: Cancer is one of the leading causes of death worldwide. The development of anticancer therapies plays a crucial role in mitigating tumour progression and metastasis. Kynurenine metabolites which include L-kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic acid and quinolinic acid have been shown to inhibit T-cell proliferation resulting in a decrease in cell growth of natural killer (NK) cells and T cells. Research showed that L-kynurenine inhibits proliferation of melanoma cells in vitro. Methods: The present study aimed to explore the in vitro influence of L-kynurenine, quinolinic acid and kynurenic acid on endothelioma sEnd-2 cells at concentration ranges of 1 mM – 4 mM for 24 h, 48 h and 72 h on cell morphology, cell cycle progression and induction of apoptosis. Results and Discussion: The half inhibitory concentration (IC50), as determined using GraphPad Prism, for L-kynurenine, quinolinic acid and kynurenic acid was 10.77 mM, 14.78 mM and 535.40 mM respectively. Optical transmitted light differential interference contrast and hematoxylin and eosin staining revealed the presence of cells blocked in metaphase, formation of apoptotic bodies and compromised cell density in L-kynurenine- and quinolinic acid- treated cells. A statistically significant increase in the number of cells present in the sub-G1 phase was observed in L-kynurenine-treated samples. Conclusion: It can be concluded that L-kynurenine exerts an antiproliferative effect on the sEnd-2 cell line by a decrease in cell growth and proliferation and metaphase block. These hallmarks suggest cell death via apoptosis. Further research will be conducted on L-kynurenine to assess the effect on cell adhesion in vitro and in vivo.

This research was supported by the following grants: The Research Development Programme at the University of Pretoria awarded to Dr YN Hlophe; National Research Foundation awarded to Dr YN Hlophe (A1F4685 & N1F580); The University Capacity Development Programme (UCDP) awarded to Ms Tatchum (A1D783 & N1F120).

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.
Strategies for Teaching About Physiological Mechanisms of Obesity in Undergraduate Pathophysiology Courses
Authors: Walton Kristen
Published: May 2024

Obesity is often viewed as a consequence of “lack of willpower” or other behavioral choices, rather than a complex array of biological and other factors. Many undergraduates in pre-nursing or biology programs have minimal exposure to the physiology and pathophysiology of obesity, including learning about leptin and other hormones involved in appetite control. Because obesity was not previously explicitly covered as s standalone topic in the pre-nursing pathophysiology course at my institution, I developed materials for teaching about the pathophysiology of obesity. These materials were designed at two different levels for use in two different pathophysiology courses: one, a survey of pathophysiology topics for pre-nursing majors, and the other, an in-depth exploration of the molecular and cellular basis of selected diseases for upper division biology majors. In both courses, a case of human leptin deficiency and the ob/ob mouse model are used to introduce the importance of hormones in appetite control and body weight. In the molecular basis of disease course, obesity is covered as part of a unit organized around metabolic syndrome. The discussion includes molecular and cellular mechanisms that link obesity to several other diseases, including type 2 diabetes and atherosclerosis. Informal feedback from students in the pre-nursing course at the end of the course suggested that students shifted their thinking about obesity from a purely behavioral phenomenon to a more nuanced understanding of obesity as a multifactorial condition. Overall, devoting class time to biological mechanisms of obesity has resulted in increased student understanding of the complex nature of body weight regulation.

None.

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.
Vascular Dysfunction and Inflammation in Liver Transplant Recipients
Authors: Barton Brittany , Chavez Domenico , Connelly Margery , Bohmke Natalie , Wolver Susan , Siddiqui Mohammad , Kirkman Danielle
Published: May 2024

INTRODUCTION Liver transplant (LT) recipients have an increased risk of developing cardiovascular disease (CVD) after transplant. The physiological mechanisms driving this risk are not fully understood. Vascular endothelial dysfunction is the initial pathophysiological step in the development of atherosclerosis. The objective of this study was to characterize vascular endothelial function in LT recipients. It was hypothesized that compared to matched healthy controls (HC), LT recipients would have impaired vascular function. METHODS. Conduit artery endothelial function was measured by flow-mediated dilation of the brachial artery (FMDBA) with duplex ultrasound in 40 LT patients (18 male, 22 female; mean ± SD: Age, 56±11 years) and 10 age matched HC (4 male, 6 female; Age 51±16 years). Central aortic blood pressures were derived from radial arterial tonometry and the use of the generalized transfer function. A venous blood sample was obtained for nuclear magnetic resonance spectroscopy assessment of the inflammation biomarker GlycA, and high-density lipoprotein (HDL) particle subspecies. A novel metabolic inflammation index was derived from plasma GlycA and HDL subparticle concentrations. RESULTS. LT recipients had higher peripheral (Median [IQR]: HC vs. LT, 119 [111-136] vs. 135 [124-147] mmHg, p=0.01) and central aortic (113 [102-126] vs. 124 [116-139] mmHg, p=0.03) systolic blood pressures. LT recipients had impaired vascular endothelial function (HC vs. LT, FMDBA: 6.08 [5.01-7.61] vs. 4.54 [3.31-6.24] %, p = 0.04). In LT recipients, the inflammation index (55 [45-62] AU) was negatively associated with vascular endothelial function ( r=-0.4, p=0.03). CONCLUSIONS. Despite optimal pharmacological intervention, LT recipients had higher systolic blood pressures and worse vascular endothelial dysfunction compared to HC. In LT recipients, a higher inflammation index was associated with worse endothelial function, suggesting that chronic low-grade inflammation may partly contribute to endothelial dysfunction in this patient population. These findings provide support for the vascular endothelium as a potential therapeutic target to improve cardiovascular health in LT recipients.

Supported by CTSA award No. UM1TR004360 from the National Center for Advancing Translational Sciences.

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.
Impact of exercise training on endothelial metabolism and skeletal muscle angiogenic potential in type 2 diabetes
Authors: Moller Sophie , Hansen Maria , Wickham Kate A. , Pedersen Thomas Å. , Åkerström Thorbjörn , Helge Jørn W. , Dela Flemming
Published: May 2024

Type 2 diabetes (T2D) is associated with vascular endothelial dysfunction and microvascular rarefaction in skeletal muscle tissue (1). Although endothelial dysfunction in metabolic disease is proposed to be associated with altered endothelial cell metabolism, there is to date a paucity of human data to support this notion. The aim of this study was to investigate the metabolism in microvascular endothelial cells derived from skeletal muscle biopsies. Moreover, as exercise training is known to reverse endothelial dysfunction and promote angiogenesis, the effect of a period of exercise training was assessed. Microvascular endothelial cells were isolated from m. vastus lateralis biopsies taken from obese individuals with (n = 7) and without (n = 8) T2D before and after 12 weeks of aerobic exercise training. Mitochondrial respiration, hydrogen peroxide (H2O2) emission, and nitric oxide (NO) formation were determined in the cells by the Oroboros Oxygraph-2K. In addition, angiogenic-, metabolic- and antioxidant enzymes and proteins, cell proliferation, and skeletal muscle capillarization were determined. At baseline, there was no difference between endothelial cells from obese control participants and T2D obese participants for any of the parameters measured: glycolytic capacity, as evidenced by a similar lactate production and PFK-1 protein content, respiratory capacity, H2O2 emission, NO emission, endothelial NO synthase protein (eNOS) content. The training period led to an overall increase in the respiratory capacity in endothelial cells from both groups (main effect, P = 0.021) whereas mitochondrial H2O2 emission remained unaltered. There was no change in glycolytic capacity, superoxide dismutase 2 or eNOS protein contents, or NO emission. Training did not influence the capillary-to-muscle fiber ratio in either group. The results of this study show that aerobic exercise training of obese control and obese diabetic subjects leads to an increase in the respiratory capacity of muscle microvascular endothelial cells. The data also indicate that there are no differences in endothelial metabolism and NO production between obese control and obese diabetic individuals. However, as the study is ongoing and only half of the subjects have been included at this time, power is limited and results may differ upon completion. Data from all subjects will be presented at the conference.

Funding: The study is funded by Novo Nordisk A/S.

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.
Mitochondrial Fragmentation Increases with Aging in Rats
Authors: Alamodi Maryam , Dasgupta Debanjali , Fogarty Matthew , Mantilla Carlos B. , Sieck Gary
Published: May 2024

The diaphragm muscle (DIAm) is the major pump muscle for breathing. Neural control of the DIAm involves recruitment of phrenic motor neurons (PhMNs) comprising motor units that vary in their mechanical and fatigue properties. Smaller PhMNs innervating fatigue resistant DIAm fibers are highly active being recruited during breathing, while larger PhMNs are infrequently recruited during more forceful expulsive behaviors. Previously, we found that to support their higher activity levels, smaller PhMNs have higher mitochondrial volume density and are less fragmented compared to larger PhMNs. With aging, larger PhMNs are more vulnerable and ~30% are lost, and those surviving display greater mitochondrial fragmentation. We also found that older rats exhibit elevated levels of the proinflammatory cytokine tumor necrosis factor alpha (TNFa), which in other tissue has been linked to mitochondrial fragmentation via activation of the IRE1a S724-mediated endoplasmic reticulum (ER) stress pathway. Accordingly, we hypothesized that in 24-month-old rats, increased TNFa levels activate the pIRE1aS724-mediated ER stress pathway, leading to XBP1s splicing, which transcriptionally increases expression of cyclin-dependent kinases (CDK1 and CDK5) that mediate phosphorylation of DRP1 at Serine 616 (pDRP1S616), and ultimately mitochondrial fragmentation. We found that serum TNFa levels increased ~3.5 fold in 24-month rats compared to 6-month rats. Consistent with elevated TNFa, we found increased pIRE1aS724 and XBP1s splicing in the cervical ventral horn of 24-month rats. In retrogradely labeled PhMNs, we found XBP1s was localized to the nucleus, consistent with transcriptional activation of gene expression. Bioinformatic analysis and ChIP assay confirmed XBP1s binding to the CDK1 and CDK5 promoter regions in rat cervical ventral horn. Both CDK1 and CDK5 mRNA and protein were elevated in the cervical ventral of 24-month rats. In aged rats, pDRP1S616 phosphorylation increased with a corresponding increase in mitochondrial fragmentation. Our results support our hypothesis that chronic inflammation (elevated TNFa levels) in older rats activate the pIRE1aS724-mediated ER stress pathway, leading to XBP1s splicing, which transcriptionally targets CDK1 and CDK5 expression mediating pDRP1S616 phosphorylation and mitochondrial fragmentation.

Research Supported by NIH R01 grant AG44615.

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.
Examining the relationship between Locus coeruleus (LC) activity and breathing in response to chemical exposure
Authors: Warden Matthew , Szujewski Caroline , Browe Brigitte , Garcia Alfredo J.
Published: May 2024

Objective: The control of breathing must continuously adapt in response to homeostatic changes. This is particularly important in the context of chemical exposure to substances such as opioids and anesthetic gases known to suppress the drive for breathing. While these agents suppress breathing through different modalities, how they affect neuromodulatory networks capable of influencing breathing remains unknown. This ongoing study aims to understand how exposure to the ultrapotent synthetic opioid (UPSO), fentanyl, and the anesthetic gas, isoflurane, affect the relationship between LC activity and breathing. Hypothesis: We hypothesize that fentanyl and isoflurane have divergent effects on the relationship between LC activity and breathing. Methods: Measurements were made using unrestrained whole-body plethysmography and fiber photometry in NET-cre positive mice expressing GCaMP8s while breathing room air (FiO2=21%) before and following the administration of either fentanyl (0.7 mg/kg i.p.) or exposure to isoflurane (1.5% inhaled). Post-hoc analyses were conducted using MATLAB. Results: Our analyses showed that awake mice (N=8) exhibited two types of LC activity. Type 1 LC activity coincided with high frequency respiratory transients (HFRTs); whereas Type 2 activity did not appear to coincide with changes in breathing. Both fentanyl (N=5) and isoflurane (N=3) suppressed breathing with a greater degree occurring with the UPSO. Furthermore, the frequency of LC activity increased during opioid-induced respiratory depression (OIRD) where both types of LC activity were evident. Isoflurane anesthetized mice showed decreased Type 1 LC activity and a reduction in the duration of Type 2 activity while breathing either room air or hypoxia (FiO2=10%). Conclusion: While isoflurane suppressed Type 1 LC activity in room air and hypoxia, fentanyl which caused a larger suppression in breathing, preserved Type 1 LC activity. These differential effects suggest that the contribution of LC activity to breathing fundamentally changes when exposed to either anesthesia or fentanyl, which may be relevant to understanding the physiological consequences of exposure to either agent.

This work was supported by NIH: R01HL163965, R01DA057767.

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 proteins differentially associated with Npt2a in the presence and absence of NHERF1
Authors: Lederer Eleanor , Gagnon Kenneth , Merchant Michael
Published: May 2024

Background: NHERF1 deficient mice are hypophosphatemic and phosphaturic due to failure of functional apical membrane localization of Npt2a. Wild type (WT) and NHERF1 knock out (KO) mice show similar proximal tubule protein expression of Npt2a. Previous studies have shown that dissociation of Npt2a and NHERF1 stimulated by PTH and FGF23 results in lysosomal degradation of Npt2a. The persistence of Npt2a expression in NHERF1 deficiency suggests a defect in Npt2a forward traffcking. Hypothesis: We hypothesized that comparison of Npt2a-associated proteins from WT and KO mouse kidney cortex would identify novel proteins critical for forward traffcking of Npt2a. Methods: We immunoprecipitated homogenized kidney cortex from WT and NHERF1 KO C57Bl6 mice using a polyclonal Npt2a antibody followed by proteomic analysis using liquid chromatography-mass spectrometry and the STRING database of known and predicted protein-protein interactions. Results: We identified 31 proteins that showed statistically significantly greater association with Npt2a in WT kidney cortex and 50 proteins that showed statistically significantly greater association with Npt2a in KO kidney cortex. We did not identify greater association of Npt2a from KO kidney cortex with any of the other known PDZ proteins known to associate with Npt2a including PDZK1 and PIST. Among the proteins more highly associated with Npt2a in KO were 14-3-3 and valacyclovir hydrolase. STRING analysis of the WT-associated proteins identified membrane transport, phosphate ion homeostasis, and oxidative phosphorylation as important biological processes. Analysis of the KO-associated proteins identified DNA unwinding, regulation of cytoplasmic translation, and clathrin-dependent endocytosis were identified as important biological processes in the absence of NHERF1. Conclusions: We conclude that the aberrantly-traffcked Npt2a in KO has successfully traversed the Golgi and is correctly folded but may interact with 14-3-3 through its PDZ binding motif, preventing forward traffcking. We also conclude that the function of Npt2a may significantly change when the cotransporter does not properly forward traffc in the absence of NHERF1 expression.

Support for EDL from Dept Veterans Affairs CX0001614 and the Pak Mineral Metabolism Center.

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.
Theoretical modeling of tumor angiogenesis: the opposing effects of vascular endothelial growth factor and angiopoietin-2
Authors: Nguyen Vivian , Secomb Timothy
Published: May 2024

Tumor microvascular networks are highly unstable, disorganized structures that obstruct cancer therapeutics by poorly distributing blood flow and oxygen. The elevated release of vascular endothelial growth factor (VEGF) by solid tumors has been widely implicated in pathological angiogenesis, or the growth of new blood vessels. However, how VEGF overexpression leads to the malformation of vascular networks is incompletely understood. Angiopoietin-2 (Ang2) is a destabilization factor that has been shown to promote sprouting in the presence of VEGF with hypoxia, but regression in its absence. Here, we hypothesize that the tumor environment, which sustains VEGF production under conditions of normoxia, also promotes Ang2-induced regression. A theoretical model is developed representing the 3-dimensional growth, remodeling, and pruning of microvascular networks in early-stage tumors to investigate the combined effects of VEGF and Ang2. Oxygen transport by the growing vascular network is simulated. VEGF production is induced by hypoxia and also elevated independent of oxygen levels in the expanding tumor region. Angiogenesis is stimulated in response to elevated VEGF levels. The model predicts that the release of VEGF in normoxic regions without counteracting factors results in very high tumor vascular densities compared to normal tissue, which is not observed experimentally. Introducing the regressive effects of Ang2 limits vascular density and produces greater variability in oxygen levels in the tumor region. Vascular networks in the tumor generated from the model show comparable densities to surrounding tissue, in which an elevated rate of sprouting is balanced by Ang2-induced regression. In this state, continuous turnover of vessels is predicted, while a relatively constant vascular density is maintained. These simulations suggest that the destabilizing role of Ang2 is an important factor that should be included in theoretical models for tumor angiogenesis. While Ang2 activity is already targeted in a number of clinical trials, clarifying the dynamic role of Ang2 may help advance angiogenesis-based therapeutic approaches.

Supported by NIH grant HL034555.

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.
Role of potassium as a coronary metabolic vasodilator
Authors: Warne Cooper , Heard Michael , Essajee Salman , Tucker Selina , Tune Johnathan , Dick Gregory
Published: May 2024

K+ release from the myocardium is associated with decreased coronary vascular resistance. Accumulation of extracellular K+ has been linked to mechanisms of vasodilation in the coronary circulation including activation of the electrogenic Na+-K+ pump in smooth muscle (Murray and Sparks, Circ. Res. 1977) and endothelial-mediated hyperpolarization via Kir2.1 channels (Zhao et al., PNAS 2020). Our objective was to examine K+ as a coronary metabolic vasodilator in vivo. Further, we addressed two potential shortcomings of previous studies: the short duration of the bolus K+ stimulus employed and the seemingly high concentrations required to produce vasodilation. We hypothesized that continuous, steady-state intracoronary infusions of K+ would produce sustained coronary vasodilation in a concentration-dependent manner. Our methods involved instrumenting anesthetized, open-chest Yorkshire swine (male and female, 60 kg) for measurements of coronary blood flow, as well as arterial and coronary venous blood sampling. The left anterior descending coronary artery was cannulated and perfused under the control of a pressure servo, allowing us to determine flow and infuse K+. Our results show small, but statistically significant (* represents p < 0.05), effects of K+ on coronary hemodynamics. The coronary venous K+ concentration was 4.0 ± 0.1 mM at baseline. Infusing K+ into the coronary artery at increasing rates increased coronary venous K+ to 4.9 ± 0.2*, 6.4 ± 0.2*, and 7.9 ± 0.2* mM. Higher K+ concentrations caused fatal arrhythmias. Coronary blood flow was 0.73 ± 0.14 ml/min/g at baseline. Infusing K+ into the coronary artery at increasing rates increased coronary blood flow to 0.78 ± 0.14*, 0.82 ± 0.15*, and 0.86 ± 0.16* ml/min/g. These small coronary blood flow changes were sustained during continuous K+ infusion. We conclude that K+ is a coronary vasodilator, as has been demonstrated previously. Importantly, however, we emphasize that the effects of K+ are extremely modest and the concentrations required to produce physiologically significant vasodilation are life-threatening. With the assumption that the venous K+ concentration is in equilibrium with that surrounding the smooth muscle and cardiac muscle of the working heart, we urge caution in interpreting isolated artery studies that routinely use 15-20 mM K+ to elicit hyperpolarization and vasodilation. Our data do not support the idea that K+ plays a major role in regulating coronary vascular resistance.

This work was supported by National Institutes of Health grant R01 HL158723.

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.