bluuebunny/crossref_metadata_2025 huggingface dataset:
Skeletal muscle derived pro-brain derived neurotropic factor promotes ischemia-reperfusion induced inflammation
Authors: Aby Katherine , Antony Ryan , Li Yifan
Published: May 2023

Skeletal muscle ischemia-reperfusion (IR) injury is prevalent in trauma, peripheral vascular diseases, and following surgical procedures, however, effective prevention and treatment for skeletal muscle IR injury are lacking. Brain-derived neurotrophic factor (BDNF), originally discovered in the brain, is expressed and released from skeletal muscle as a myokine. However, the transcription splice variants, posttranslational modifications, and functions of BDNF in skeletal muscle are poorly defined. In this study, we first showed that skeletal muscle expressed unique splice variants of BDNF compared to the brain. At the protein level, Western blot comparing BDNF in brain and skeletal muscle revealed that skeletal muscle expresses significantly more proBDNF than mature BDNF under basal conditions, opposite to brain tissue. Consistent with this, the levels of the major protein convertases in skeletal muscle were significantly lower compared to the brain, suggesting that the high level of proBDNF is at least partially due to the low cleavage activity in skeletal muscle. The potential function of the proBDNF in disease conditions was then examined in mice with skeletal muscle IR injury. IR injury was induced in 3-month-old male and female C57BL/6 mice by placing a tourniquet on one hind limb for 1 hour, then removing it, allowing reperfusion for 1-14 days, with the contralateral hind limb serving as a control. We hypothesize that proBDNF may be necessary for facilitating the inflammatory response, while mature BDNF may be necessary for promoting inflammation resolution and myogenesis following IR injury. Remarkably, the level of proBDNF, but not mature BDNF, was increased significantly in IR muscle compared to the contralateral control (p=0.013). This was accompanied by increased proinflammatory cytokines and macrophage infiltration in the injured muscle. Mice with skeletal muscle-specific knockout of BDNF showed a significant reduction in proinflammatory cytokine production and macrophage infiltration following IR injury compared to wild-type animals. To confirm the role of proBDNF in this finding, the receptor for proBDNF, p75NTR, was blocked using the small molecule LM11A-31. In IR injured muscle, LM11A-31 treatment significantly reduced the proinflammatory response and macrophage infiltration compared to control animals, similar to what is seen in BDNF knockout animals. Collectively, these results indicate that myokine proBDNF promotes inflammation and macrophage recruitment in the IR-injured muscle, and therefore is a potential target for the treatment of skeletal muscle injury.

This work was funded by NIH grant R01HL147105 and NIH Training Grant T32-GM136503.

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.
Use of Simplex Learning Index to Identify a Course Deficit
Authors: Bao Sujin
Published: May 2023

Difficulty index and its derivative performance index (PFI) have been commonly used to measure student learning outcomes. However, these indices have a high volatility and low sensitivity. This work has established simplex learning index (SLI) that has a low volatility and high sensitivity. To construct SLI, students were divided into two groups based on their scores on the whole quiz. The item SLI and lecture SLI were derived from the results of students in the high-scoring group. Exam results from 9 cohorts of medical students in two phases of learning were analyzed. The volatility, measured by the ratio between the standard deviation and the mean, was >65% lower in SLI than in PFI. Using the lecture SLI as a metric, one lecture B22 (Metabolism of Amino Acids) was identified that had an average SLI of 0.66 in earlier four student cohorts in Phase 1 learning. Two major changes were made on the lecture – lecture organization and the delivery method – in Phase 2. Students from recent five cohorts in Phase 2 had an average SLI of 0.84, which was 26.6% higher than that in Phase 1 ( P<0.02). In contrast, when using PFI, the change was only 13.46% and insignificant ( P=0.29). In the same period, implementation of the same delivery method did not yield significant changes in learning outcomes in lecture B24 (Metabolism of Nucleotides). Taken together, this work shows that SLI is a better indicator for learning outcomes and suggests that lecture reorganization is the key to improved student learning.

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.
Identification of a panel of plasma protein biomarkers for determining Chronic Traumatic Encephalopathy in adults
Authors: Zafar Umema , Habib Syed Hamid , Bashir Shahid
Published: May 2023

Importance: Chronic Traumatic Encephalopathy (CTE) which results from trauma to the head can be a debilitating condition. If the patient luckily has no complications immediately, the long-term effects like gradually progressing tauopathy can seriously affect the individual's quality of life. This review aims to identify a panel of plasma neurobiomarkers that can be used to screen CTE in adults. Observations: This is a scoping review based on the methodological framework presented by Arksey & O'Malley, in 2005. Keywords were used to search the literature and articles were screened to identify the plasma biomarkers involved in chronic brain injury. A total of 38 plasma protein biomarkers were identified. A rubric was designed keeping in view the characteristics highlighted in the literature. The biomarkers were then scored on the basis of the rubric devised. The biomarkers which obtained the highest scores were Neurofilament Light chain (NfL), Phosphorylated forms of tau (P-Tau), and Neuron specific enolase (NSE) with 12, 12, and 11 scores respectively. Both NfL and p-Tau are present in serum and Cerebrospinal fluid (CSF) with equal sensitivity. Both originate mainly from the brain, are present at the pico level of quantification, and represent chronic brain injury. NSE on the other hand is detected with higher sensitivity in CSF than in blood. The rest of its qualities equate with those of NfL and p-Tau. Conclusion and relevance: In conclusion, NfL, p-Tau, and NSE have the optimum characteristics that are the best fit for diagnosing CTE as compared to other biomarkers. The specificity in terms of origin from the brain, representation of chronic brain trauma, and detecting the smallest amount present in plasma with almost the same detection sensitivity as CSF, are the qualities that make these biomarkers the most suitable ones.

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.
The prevalence and predictors of tidal expiratory flow limitation during peak exercise do not differ between genders in healthy adolescents and young adults.
Authors: Welch Ryan , Kolbe John , Kevin Ellyett
Published: May 2023

Introduction: Tidal expiratory flow limitation (EFLT) occurs when the tidal breath reaches its maximal capacity to generate flow despite increased expiratory effort. It has been suggested there are gender differences; females tend to develop EFLT due to lower markers of ventilatory capacity, and the primary determinants of EFLT in males relate to higher oxygen demand. Aim/hypothesis: This study aimed to determine the prevalence and predictors of EFLT during peak exercise in healthy subjects aged 10-24 years. We hypothesised that the prevalence and predictors of EFLT would not differ between males and females. Method: Healthy, physically active subjects (n=122, 69M:53F) with normal spirometry and gas exchange completed a maximal cardiopulmonary exercise test. The presence and degree of EFLT during peak exercise was determined by the vector-based analysis technique described by Welch et al (2021). Student’s T-test compared continuous variables and predictors of EFLT were determined by two-way ANOVA for sex and the presence of EFLT. Results: EFLT was present in 70% of subjects, with no difference in the prevalence between males and females (74 vs. 66%). The degree of EFLT was significantly greater in the males compared to females (40 vs. 30% of tidal volume, p<0.05). Subjects demonstrating EFLT had relatively lower forced expired volume in the first second (FEV1), FEV1/forced vital capacity ratio, and mid expiratory flows. During peak exercise, male and female subjects demonstrating EFLT had higher relative peak oxygen consumption, ventilatory equivalents, breathing frequency, and minute ventilation relative to body weight. Conclusion: This study showed no gender difference in the prevalence of EFLT in healthy, physically active subjects. For both genders, lower markers of ventilatory capacity and higher markers of oxygen demand were predictors of EFLT.

This research was supported by an award from The Green Lane Research and Education Fund Board.

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.
Effect of Rebreathing-Induced Intermittent Hypoxia on Glucose Tolerance in Adults with Type 2 Diabetes
Authors: Zhao Jiahui , Guei Jamie , Lalande Sophie
Published: May 2023

Hypoxia stimulates glucose uptake through an insulin-independent pathway. The aim of this study was to examine the acute effect of rebreathing-induced hypoxia on plasma glucose and insulin levels in adults with type 2 diabetes. We hypothesized that rebreathing-induced hypoxia would attenuate the increase in glucose and insulin levels during an oral glucose tolerance test. Nine individuals with type 2 diabetes (5 men, age: 53±10 years, body mass index: 35±7 kg/m2, HbA1c: 7.1±0.5%) visited the laboratory on two occasions. On both visits, a 2-hour, 75 g oral glucose tolerance test was conducted while simultaneously performing a rebreathing-induced hypoxia protocol (RIH) or breathing room air (Norm). Venous blood samples were collected 0, 30, 60, 90, and 120 min following ingestion of the high-glucose drink to measure plasma glucose and insulin levels. The rebreathing-induced hypoxia protocol consisted of two series of five 2-min rebreathing bouts in a low-volume, closed circuit system interspersed with two minutes of breathing room air. The first and second series of rebreathing bouts were performed within the first 30 min and 30-60 min after ingestion of the high-glucose drink, respectively. Rebreathing-induced hypoxia resulted in a nadir oxygen saturation of 88±4 % and a nadir fraction of inspired oxygen of 12±5%. Plasma glucose responses to the oral glucose tolerance test were not different between conditions, however, insulin levels were lower during rebreathing-induced hypoxia than normoxia (RIH vs. Norm: 0: 17±13 vs. 21 ±14; 30: 37 ±28 vs. 42±26; 60: 57±32 vs. 77±52; 90: 88±67 vs. 116±81; and 120: 114±96 vs. 136 ±111 ulU/ml, p=0.03), suggesting an acutely improved insulin sensitivity. Accordingly, the insulin area under the curve was lower during rebreathing-induced hypoxia than normoxia (124±84 vs. 157±102, p=0.02). In conclusion, exposure to short and intermittent rebreathing-induced hypoxia following the ingestion of a high-glucose drink acutely improves insulin sensitivity in adults with type 2 diabetes. Rebreathing-induced hypoxia could therefore represent a novel and simple strategy to improve glycemic control in individuals living with type 2 diabetes.

College of Education Small Grants Program

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.
Melanocortin 4 receptor signaling in Sim-1 neurons permits sexual receptivity in female mice
Authors: Hill JH , Harberson Mitchell , Semple Erin
Published: May 2023

Female sexual dysfunction affects approximately 40% of women in the United States, yet few therapeutic options exist for these patients. The melanocortin system is a new treatment target for Hypoactive Sexual Desire Disorder (HSDD), but the neuronal pathways involved are unclear. In this study, female MC4R knockout mice lacking melanocortin 4 receptors (MC4Rs) paired with males were found to approach males less and have reduced receptivity to copulation, as indicated by a low lordosis quotient. The mice were then bred to express MC4Rs exclusively on Sim1 neurons (tbMC4RSim1 mice) or on oxytocin neurons (tbMC4ROxt mice). Lordosis behavior was normalized in tbMC4RSim1 mice and improved in tbMC4ROxt mice. In contrast, approach behavior was unchanged in tbMC4RSim1 mice but greatly increased in tbMC4ROxt animals. The changes were independent of melanocortin-driven metabolic effects. These results implicate MC4R signaling in Oxt neurons in appetitive behaviors and MC4R signaling in Sim1 neurons in female sexual receptivity, while suggesting melanocortin-driven sexual function does not rely on metabolic neural circuits.

R01HD081792

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.
Potential role of brown adipose tissue-derived extracellular vesicles in mediating the cardioprotective effect of CNS leptin infusion after ischemia/reperfusion injury
Authors: Omoto Ana Carolina Mieko , Vechetti Ivan , Rule Blake , do Carmo Jussara , da Silva Alexandre , Aitken Nikaela , Dai Xuemei , Nelson Benjamin , Wang Zhen , Li Xuan , Mouton Alan , Hall John
Published: May 2023

Ischemic heart disease is the leading cause of death in the U.S. and worldwide. We recently demonstrated that infusion of leptin into the central nervous system (CNS) dramatically improves cardiac metabolism and function following ischemia/reperfusion (IR) injury. How the brain communicates with the heart during central leptin infusion to improve cardiac function after IR injury is still unknown. One potential mechanism may be via activation of brown adipose tissue (BAT), as central leptin administration has been shown to induce BAT-mediated thermogenesis. Furthermore, BAT has been proposed as an important source of extracellular vesicles (EVs) carrying bioactive molecules with cardioprotective effects. Thus, we investigated whether BAT contributes to the cardioprotective effect of central leptin infusion and the potential role of EVs in this protection. Male Sprague-Dawley rats (~8 weeks of age) were submitted to interscapular BAT ablation (iBATx) and instrumented with an intracerebroventricular (ICV) cannula in the brain lateral ventricle. After recovery and baseline assessment of cardiac function by echocardiography (ECHO), myocardial IR was induced by temporary (60 min) ligation of the left anterior descending coronary artery. Vehicle (saline, 0.5 μL/hr) or leptin (0.62 μg/hr) was infused chronically for 28 days starting 30 min after reperfusion using osmotic pumps implanted subcutaneously in the scapular region and connected to the ICV cannula. Cardiac function was assessed weekly by ECHO. Another set of animals with intact iBAT was treated with ICV leptin or vehicle for 2 weeks and had their iBAT collected for EVs isolation and quantification by differential ultracentrifugation and nanoparticle tracking analysis, respectively. Compared to vehicle-treated animals, ICV leptin infusion increases iBAT-derived EVs (5.6x109 vs 1.6 x109 particles/mg of tissue), and removal of iBAT prevent leptin’s CNS-mediated cardioprotective effects after IR injury as indicated by a lack of improvement in ejection fraction (26.9±2.5 vs 40.9±1.2%), stroke volume (154.6±15 vs 275.3±8μL) and global longitudinal strain (-7.4±1.1 vs -13.9±0.5%) at week 4 post-IR. These results suggest that the BAT plays an important role in mediating the cardioprotective effect of CNS leptin administration after I/R injury and that iBAT-derived EVs may be involved in delivering protective molecules to the heart during central leptin infusion.

AHA 835218, NIGMS P20GM104357, NIDDK R00DK113280, R01DK121411 and P20GM104320

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.
Impaired Erythropoietin Response to Intermittent Hypoxia in Patients with Type 2 Diabetes
Authors: Wojan Frank , Stray-Gundersen Sten , Zhao Jiahui , Lalande Sophie
Published: May 2023

Patients with type 2 diabetes (T2D) exhibit, on average, a 20% decline in maximal oxygen consumption when compared to healthy adults. Hemoglobin mass strongly correlates to maximal oxygen consumption. A reduced total blood volume has been observed in patients with T2D, suggesting that a reduced hemoglobin mass contributes to the decreased maximal oxygen consumption in this population. Hypoxia stimulates the release of erythropoietin (EPO), the hormone regulating red blood cell production. We previously showed that intermittent hypoxia, consisting of alternating short bouts of breathing hypoxic and normoxic air, increases EPO levels. Thus, the objective of this study was to determine the effect of a single session of intermittent hypoxia on serum EPO levels and hemoglobin mass in patients with T2D. We hypothesized that a single session of intermittent hypoxia would raise serum EPO levels and lead to an increase in hemoglobin mass in patients with T2D. Ten patients with T2D (4 women, age: 53 ± 10 years, body mass index: 36.2 ± 8.5 kg/m2, HbA1c: 7.2 ± 1.2%) were exposed to an intermittent hypoxia protocol consisting of eight 4-min cycles at a targeted oxygen saturation of 80% interspersed with normoxic cycles to resaturation. Air was made hypoxic by titrating nitrogen into a breathing circuit. Pulmonary gas exchange, oxygen saturation, and hemodynamics were continuously measured throughout the protocol. EPO levels were measured before and 4.5 hours after the beginning of the protocol. Hemoglobin mass was assessed via carbon monoxide rebreathing before and seven days following intermittent hypoxia. Intermittent hypoxia lowered oxygen saturation (­­97 ±­ 2 to 81 ± 2%, p<0.01), which resulted in a lower fraction of inspired oxygen (20.8 ±­ 0.1 to 11.1 ± 1.0%, p<0.01). There was no significant change in EPO levels following exposure to intermittent hypoxia (11.9 ± 5.3­ to 12.1 ± 4.3 mU/ml, p=0.83). There was also no change in hemoglobin mass in response to intermittent hypoxia (864 ± 152­ to 850 ± 150 g, p=0.64). Intermittent hypoxia did not affect mean arterial pressure (94 ± 5 to 97 ± 7 mmHg, p=0.18) but increased cardiac output (9.1 ± 2.7 to 9.8 ± 2.8 L/min, p=0.03) due to an increase in heart rate (78 ± 9 to 84 ± 10 bpm, p<0.01). In conclusion, a single session of intermittent hypoxia did not increase serum EPO levels or hemoglobin mass in patients with T2D. These findings suggest an impaired EPO response to decreased oxygen levels in patients with T2D, which may contribute to the reduced hemoglobin mass and total blood volume observed in this population.

College of Education Small Grants Program

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.
Effect of cyclooxygenase inhibition on thermal hyperemia in skeletal muscle of humans
Authors: Richey Rauchelle , Cope Heidi , Ruiz Ysabella , Moore Amy , Walsh Mackenzie , Olivencia-Yurvati Albert , Romero Steven
Published: May 2023

Acute heat exposure increases skeletal muscle blood flow in humans. However, the vasodilator mechanisms mediating this hyperemic response remain unknown. The cyclooxygenase pathway is active in skeletal muscle, is heat sensitive, and contributes to cutaneous vasodilation during heat exposure in young healthy humans. Therefore, the purpose of this investigation was to test the hypothesis that inhibition of cyclooxygenase via high dose ingestion of ibuprofen would attenuate blood flow in the vastus lateralis muscle during localized heating. Four participants (26 ± 2 yrs) were studied on two separate occasions: 1) time control; 2) ingestion of 800 mg ibuprofen, a non-selective cyclooxygenase inhibitor. Experiments were randomized, counter-balanced, and separated by at least 10 days. Microdialysis was utilized to bypass the cutaneous circulation and directly measure local blood flow in the vastus lateralis muscle of each leg via the ethanol washout technique. Pulsed short-wave diathermy was used to induce deep heating of the vastus lateralis for 90 min, whereas the contralateral leg served as a thermoneutral control. Local muscle temperature was measured within ~1-2 cm of each microdialysis probe via a thermocouple. Temperature of the vastus lateralis measured through 90 min of heating did not differ between conditions (control, 39.2 ± 1.0 °C; ibuprofen, 39.7 ± 1.0 °C; P = 0.6 for interaction). Interestingly, local blood flow increased during heat exposure, but did not differ between control (baseline, 15 ± 11 mL· min-1 · 100g-1; 30 min, 23 ± 12 mL· min-1 · 100g-1; 60 min, 25 ± 12 mL· min-1 · 100g-1; 90 min, 38 ± 12 mL· min-1 · 100g-1) and ibuprofen (baseline, 14 ± 11 mL· min-1 · 100g-1; 30 min, 29 ± 12 mL· min-1 · 100g-1; 60 min, 32 ± 12 mL· min-1 · 100g-1; 90 min, 53 ± 12 mL· min-1 · 100g-1; P = 0.2 for interaction) conditions. Muscle temperature and local blood flow did not differ between conditions or across time for the thermoneutral leg (both P > 0.3). Taken together, cyclooxygenase-derived vasodilator prostanoids do not appear to contribute to thermal hyperemia in skeletal muscle of young healthy humans.

This work was supported by grants from the National Institutes of Health (T32 AG020494; R01AG059314) and the American Heart Association (TPA958179).

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.
Endothelin-1 Contributes to Reduced Endothelial Function in Middle-aged/Older Men with Low Testosterone
Authors: Babcock Matthew , DuBose Lyndsey , Stauffer Brian , Moreau Kerrie
Published: May 2023

Male aging is associated with a general decline in serum testosterone (T) concentrations. Low endogenous T is associated with increased cardiovascular disease risk, and we recently demonstrated accelerated age-related endothelial dysfunction, measured by brachial artery flow mediated dilation (FMD), in middle-aged/older (MA/O) men with low T compared with age-matched men with normal T. Endothlin-1 (ET-1) is a potent vasoconstrictor that is modulated by sex hormones and contributes to age-associated endothelial dysfunction. However, whether ET-1 contributes to reduced FMD in MA/O men with low T has yet to be determined. PURPOSE: to determine if ET-1 contributes to reduced FMD in MA/O men with low T. HYPOTHESIS: we hypothesized that MA/O men with low T would have higher ET-1 concentrations compared with young and MA/O men with normal T. Additionally, we hypothesized that there would be an inverse relation between ET-1 and FMD. METHODS: 60 men were categorized as either young (18-40 years, T: 400-1000 ng/dL) or MA/O (50-75 years) with low (<300ng/dL) or normal (400-1000 ng/dL) serum total T. T was determined from a venous blood draw using a one-step competitive enzyme linked immunosorbent assay. Endothelial function was determined using brachial artery FMD and ET-1 concentrations were determined using radioimmunoassay from a venous blood sample. RESULTS: T concentrations were significantly lower in MA/O men with low T (269±48 ng/dL) compared to young (500±58 ng/dL; p<0.001) or MA/O men with normal T (512±115, ng/dL; p<0.001). There was no difference in T between MA/O men with normal T and young men (p=0.995). MA/O men were similar in age (low T=59±8, normal T=60±6 years; p=0.996) and older than young men (29±4 years; p<0.001 compared to MA/O with both low and normal T). Age-associated reductions in FMD (young=7.3±1.3 vs. MA/O normal T=5.7±2.2%; p=0.019), were exaggerated in MA/O men with low T (4.0±1.7%; p=0.010 vs. MA/O normal T, p<0.001 vs. young). ET-1 concentrations were similar between young and MA/O men with normal T (young= 5.6±0.9 vs. MA/O normal T=6.0±1.4 pg/mL; p=0.768), and higher in MA/O men with low T (7.7±2.8 pg/mL; p=0.002 vs. young, p=0.016 vs. MA/O normal T). There was a moderate inverse association between FMD and ET-1 (r=-0.374, p=0.003). CONCLUSIONS: These data suggest that the greater age-associated endothelial dysfunction in MA/O men with low T may be related to elevations in ET-1. Future studies should examine the effects of low T on endothelin receptors ETA and ETB, as well as factors that could explain the increase in ET-1 in MA/O men with low T.

Supported by NIH Grants R01AG049762, U54AG062319, and T32AG000279-16A1

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.
Single-Cell RNA Sequencing Reveals Roles of Renal Lymphatic Endothelial Cells in Cisplatin Induced Acute Kidney Injury
Authors: Creed Heidi , Rutkowski Joseph
Published: May 2023

In the United States an estimated 50% of ICU patients develop Acute Kidney Injury (AKI) which is associated with a 50% mortality rate. A single occurrence of AKI predisposes a patient to develop chronic conditions such as Chronic Kidney Disease (CKD). The mechanism of the AKI to CKD transition is still unknown but is likely mediated by the extent and length of the inflammatory response following the initial injury. Lymphatic vessels help to maintain tissue homeostasis through fluid, macromolecule, and immune modulation. Increased lymphatic growth, or lymphangiogenesis, often occurs during inflammation and plays a role in acute and chronic disease processes. We have previously demonstrated that an expanded lymphatic network in KidVD mice increases the CD4:CD8 Tcell ratio and that this may afford protection from an AKI-to-CKD transition. The primary objective of this study was to understand what roles renal lymphatic endothelial cells (LECs) play in AKI recovery and CKD progression, a role which remains largely unknown. To determine if LECs have protective immunomodulatory roles in kidney injury, we utilized male C57/BL6 mice and a single 20 mg/kg Cisplatin dose to induce AKI and isolated renal LECs 72hrs post-injury. Using Seurat, ENRICHR, and STRING protein interaction analyses we defined and identified three LEC populations. Upon Cisplatin injury differences in gene expression revealed alterations in signaling pathway enrichment for (1) immunoregulatory interactions; (2) blood and lymphatic vessel development; and (3) T cell development. These findings illustrate specific differences in immune pathway activation between uninjured and injured renal LECs in regulating the inflammatory response in AKI. Together, this data indicates renal LECs may alter immunological outcomes in injury and uncovers previously unknown molecular roles in kidney injury.

NIDDK R01(JMR): 1R01DK119497-01A1, AHA Predoctoral Fellowship (HAC): 916334

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.
An Evolutionarily Conserved Olfactory Receptor Is Required for Sex Differences in Blood Pressure
Authors: Xu Jiaojiao , Choi Rira , Gupta Kunal , Warren Helen , Santhanam Lakshmi , Pluznick Jennifer
Published: May 2023

Olfactory receptor 558 (Olfr558) is expressed in the kidney where its functional role is unknown. Using RNAScope, we find that Olfr558 localizes to vascular smooth muscle, including the renal afferent arteriole. Thus, we measured blood pressure (BP) in Olfr558 wild-type (WT) and knockout (KO) mice. Systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) were measured in whole-body Olfr558 wild-type (WT) and knockout (KO) via telemetry. It is known that males have a higher BP than premenopausal females in both humans and mice; indeed, we find Olfr558WT males (M) have higher BP than females (F, n=7-9 per group), including MAP (M:101.0±1.6 vs. F:89.0±0.9 mmHg, p<0.0001), SBP (M:113±2 vs. F:102±1mmHg, p=0.0025), and DBP (M: 89±2 vs. F:75±01mmHg, p<0.0001). However, sex differences in BP are entirely absent in Olfr558 KO (MAP M: 96±2 vs. F: 95±1mmHg; SBP M: 110±2 vs. F: 108±2mmHg; DBP M: 81±2 vs. F: 82±2mmHg). Of note, other sex differences (body weight) are intact in KO, and KO males and females are fertile. To characterize this phenotype, renin expression was analyzed by qPCR, plasma renin activity (PRA) was measured by ELISA, and vasoreactivity was examined ex vivo by wire myography (responses to potassium chloride (KCl), phenylephrine (PE), acetylcholine (Ach), and sodium nitroprusside (SNP) in aortic and mesenteric rings). In male KOs (n=10-12), there was a decrease in kidney renin mRNA (0.4±0.1 vs WT: 1±0.1 p=0.001) and PRA (201±21 vs WT: 402±15, p=0.001); these parameters were unchanged in female KOs. Male KO aortic rings exhibit less constriction to PE, male KO mesenterics exhibit more relaxation to SNP, and female KO aortic rings exhibit more constriction to KCl. In females, pulse wave velocity (PWV) and tensile testing revealed that KO females have increased PWV (KO: 4.6±0.4 vs WT: 3.2±0.2 m/s, p=0.0069, n=8-11), but no changes in tensile testing. The human ortholog of Olfr558, OR51E1, was previously identified as a locus associated with DBP. Using UK Biobank data (N~450k), we find that a rare OR51E1 missense variant has a statistically significant sex interaction effect with DBP ( p=0.015), increasing DBP (+6.28mmHg) in women but decreasing it (-4.77mmHg) in men (similar to the phenotype in M and F Olfr558 KO mice). Finally, we express OR51E1 variants in HEK 293T cells and characterize how two different clinically relevant OR51E1 variants influence OR51E1 signaling. In sum, our findings demonstrate that an evolutionarily conserved olfactory receptor is required for sex differences in BP. Olfr558 regulates BP in males via renin and vascular reactivity, but via arterial stiffness in females.

Funding: R56DK107726

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.
The impact of food insecurity on academic motivation
Authors: Nagorny Katerina , Welch Megan , Rosenberg Lexis , Chowdhury Ushima , Bubis Sabrina , Begdache Lina
Published: May 2023

Food insecurity is a pressing issue affecting many people nationwide, although it disproportionately affects college students. The association between food insecurity and academic performance has been addressed in the literature; however, its impact on academic motivation has yet to be studied. Food insecurity is defined as the lack of access to reliable and nutritious food. Typically, obtaining enough food is a significant focus for those who are food insecure and may hinder time spent on other responsibilities, such as academics. This study aims to analyze the impact of food insecurity on the motivation to devote time and resources to succeed academically. It is hypothesized that food insecurity is inversely related to academic motivation and diet quality and positively correlated to mental distress. An anonymous survey was administered through social media to individuals over the age of 18. The survey included demographic questions and seven validated scales, including the Food Mood Questionnaire, Brief Resilience Scale, Academic Motivation Scale, Food Insecurity Experience Scale, Perceived Stress Scale, Kessler-6 Psychological Distress Scale, and the Stress Mindset Measure. These scales measured dietary and exercise habits, food insecurity status, academic motivation, stress, resilience, mental distress, and perceived stress. Data from 1005 individuals were analyzed using Spearman’s Rho correlation in IBM SPSS Version 25.0. The results indicate that skipping a meal and not having enough to eat are positively correlated with not having a good reason to go to college (p<0.01), and being hungry but not eating due to lack of money or resources is positively correlated with feeling like time is being wasted in school (p<0.01). Further, it was found that being unable to eat healthy and nutritious food was positively related to eating fast food (p<0.01). Our results suggest that increased food insecurity and a nutritiously deficient diet may negatively impact academic motivation. Further, food insecurity may increase mental distress, negatively impacting academic motivation.

Binghamton 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.
Cardiomyocyte-specific GPR22 overexpression ameliorates cardiac injury in mice with acute myocardial infarction
Authors: Leu Steve
Published: May 2023

The activation of G protein-coupled receptors (GPCR) signaling by external stimuli has been thought to play roles in inducing cardiac stress and stress responses. GPR22 is an orphan GPCR expressed in brains and hearts, while its expression level is associated with cardiovascular damages in diabetes. Previous studies indicated that loss of GPR22 expression increases the susceptibility to heart failure-post ventricular pressure overload, suggesting a protective role of GPR22 in mechanical cardiac stress. However, the participation and underlying signaling of GPR22 in cardiac stress response to ischemic stress remain unknown. In this study, we applied cultured cells and a transgenic mouse model with cardiomyocyte-specific GPR22 overexpression to examine the influence of ischemic stress on GPR22 expression as well as to determine the role of GPR22 in myocardial ischemic injury. To induce acute myocardial infarction (AMI), left coronary artery ligation was performed on eight-week-old male GPR22 transgenic mice, followed by histopathological and biochemical examination four weeks post-induction of AMI. Results showed that GPR22 expressions in H9C2 and RL-14 cells, two cardiomyocyte cell lines, were reduced by cobalt chloride (CoCl2) treatment. Reduced expression of myocardial GPR22 was also observed in mice with acute myocardial infraction (AMI). Histopathological examinations demonstrated the protective role of GPR22 overexpression in ameliorating myocardial infarction in mice with AMI. Furthermore, the myocardial level of Bcl-2 and activation of PI3K-Akt signaling were reduced by ischemic stress and increased by GPR22 over-expression. In conclusion, myocardial ischemic stress reduced the cardiac expression of GPR22, while overexpression of GPR22 in cardiomyocytes upregulated Akt signaling and ameliorated myocardial injury induced by ischemic stress.

This research was funded by the Chang Gung Medical Foundation (CMRPG 8K0321) and the National Science and Technology Council, Taiwan (NSC 111-2320-B-182A-005-MY2)

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.
Aging Associated Changes in Autophagy Markers in Mouse Lumbar Motor Neurons
Authors: Jahanian Sepideh , Pareja-Cajiao Miguel , Gransee Heather , Sieck Gary , Mantilla Carlos
Published: May 2023

Autophagy is a process through which damaged cytoplasmic structures are recycled and degraded within the cell. Aging can affect autophagy regulation in different steps and lead to the accumulation of altered proteins, leading to cell damage and death. Motor neuron (MN) loss is an important contributor to sarcopenia age-dependent motor dysfunction. Understanding the regulatory mechanisms of autophagy can help elucidate the motor dysfunction that occurs with aging and provide a target for developing future therapeutic agents. Previous immunofluorescence imaging studies in phrenic MNs showed an age-dependent increase in key autophagy proteins LC3 and p62, reflecting autophagosome accumulation and autophagy impairment. Accordingly, we hypothesized that aging in lumbar MNs leads to autophagy impairment reflected in regulatory protein expression. The current study assessed autophagy in choline acetyltransferase-positive MNs from spinal levels L1-L6, focused on crural muscles (extensor digitorum longus and soleus), using confocal immunofluorescence imaging. Expression of LC3 and p62 proteins in MNs were determined in male and female C57BL/6 mice at 6-, 18- and 24- months of age. Increased expression of LC3 in lumbar MNs was observed with aging across all three age groups and p62 expression in lumbar MNs was significantly increased by 24- and 18-months compared to 6-months (p<0.001). There was no sex effect observed in LC3, but p62 was significantly higher in lumbar MNs of female mice (p=0.007). Expression of both LC3 and p62 increased diffusely in ventral lumbar gray matter regions with age (p<0.001), an effect that was predominant in male and not female mice. Taken together, the results of this study provide evidence for that age-dependent changes in autophagy markers expression occurs in regions of the spinal cord (motor neurons and ventral horn gray matter). The neuronal mechanisms of aging effects include dysregulation of autophagy.

Supported by NIH R01 AG057052.

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.
Ryanodine receptor 3 impacts on the expression of aminopeptidase in mammalian skeletal muscle cells during myogenic differentiation
Authors: Ito Rika , Yokoyama Shingo , Ohashi Kazuya , Hagiwara Arisa , Takeo Yusuke , Egawa Tatsuro , Asakura Atsushi , Goto Katsumasa
Published: May 2023

In mammalian skeletal muscle, ryanodine receptor (Ryr) expresses in the membrane of sarcoplasmic reticulum (SR), and is known as Ca2+-releasing channel. Ryr in mammalian skeletal muscle consists of 2 isoforms, Ryr1 and Ryr3. Ryr1 is coupled with dihydropyridine receptors (DHPRs) in transverse tubules, and Ca2+ release is a key step for the excitation-contraction coupling (E-C coupling). However, a physiological role of ryr3 is still unclear. Recently, we confirmed that Ryr3 knockdown induces abnormal myotube formation of C2C12 cells. Further, it is reported that the abnormal shape of C2C12 myotubes were observed by the knockdown of puromycin-sensitive aminopeptidase, a selective hydrolyze of amino acid residue from the N-terminus of peptide and proteins. In the present study, we investigated that the molecular mechanisms for the abnormal myotube formation of C2C12 cells following the knockdown of Ryr3. Aggregation of phalloidin-stained actin fibers were observed in Ryr3-knockdown myotubes. On the other hand, a significantly decrease in the mRNA expression level of puromycin-sensitive aminopeptidase and endoplasmic reticulum aminopeptidase 1 was observed in Ryr3-knockdown C2C12 cells (p<0.05). Therefore, Ryr3 may play a crucial role in the quality control of proteins and peptides during myogenic differentiation via the up-regulation of puromycin-sensitive aminopeptidase and endoplasmic reticulum aminopeptidase 1.

This study was partially supported by JSPS KAKENHI (18H03160, K.G.; 19K22825, K.G.; 19KK0254, K.G., S.Y., T.E.; 22H03474, K.G., T.E.; 22K19722, K.G., T.E.; 22H03319, K.G., T.E.; 22K18413, K.G., T.E.), a grant from Graduate School of Health Science, Toyohashi SOZO University (K.G.), and a research grant from Toyohashi SOZO university (K.G.). All authors declare that they have no conflicts of interest.

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.
TRPV1 on the endings of thin fiber muscle afferents is not needed to evoke the exercise pressor reflex
Authors: Anselmi Laura , Ruiz-Velasco Victor , Stocker Sean , Higgins Shannon , Ducrocq Guillaume , Kaufman Marc
Published: May 2023

Laura Anselmi, Victor Ruiz-Velasco, Sean D. Stocker, Shannon P. Higgins, Guillaume P. Ducrocq and Marc P. Kaufman. The role played by the transient receptor potential vallinoid-1 (TRPV1) on the endings of thin fiber muscle afferents in evoking the exercise pressor reflex is controversial. To shed light on this controversy, we used TRPV1-/- rats that were made by a CRISPR-Cas9 deletion to introduce a 26-bp frameshift deletion in exon 3. We compared the magnitude of the reflex between TRPV1 +/+ wild-type rats (WT), TRPV1+/- heterozygous rats (HET), and TRPV1-/- knockout rats (KO). The exercise pressor reflex was evoked by stimulating the tibial nerve (40Hz, 0.01ms, 1.5 times motor threshold) in precollicular decerebrated unanesthetized rats whose femoral arteries were either freely perfused or were occluded for 30 sec before the start of contraction. We found that there was no difference between the magnitude of the reflex in the three groups of rats with freely perfused hindlimbs (p=0.61). Specifically, the exercise pressor reflex averaged 16.4 ± 2.2 mmHg in WT rats (n=9), 21.1 ± 5 mmHg in HET rats (n=9), and 17.7 ± 2.3 mmHg in KO rats (n=9). No difference was also observed among the three groups of rats that received acute femoral artery occlusion (p=0.79). Specifically, the peak exercise pressor reflex averaged 15.3 ± 2.2 mmHg in WT rats (n=4), 19.8 ± 4.7 mmHg in HET rats (n=6), and 19 ± 8 mmHg in KO rats (n=3). Stimulation of the tibial nerve after paralysis of the rats with pancuronium (iv) had trivial effects on arterial pressure indicating that the pressor responses to contraction were not caused by electrical stimulation within the axon of the tibial nerve. Intra-carotid arterial injection of the TRPV1 agonist, capsaicin (0.5 mg), evoked a significant pressor response in the WT rats (34.7 ± 9.2 mmHg) and in the HET rats (36.3 ± 7.2 mmHg), but not in the KO rats (3.2 ± 0.4 mmHg). In electrophysiological studies of dorsal root ganglion cells innervating the gastrocnemius muscles, capsaicin evoked inward currents in the WT and HET rats, but not in the KO rats. Moreover, immunofluorescence revealed the presence of TRPV1 in the DRG of WT, but not in the DRG of KO rats. We conclude that TRPV1 is not needed to evoke the exercise pressor reflex either in rats whose femoral arteries were either freely perfused or were occluded. These results are consistent with our previous finding that pharmacological antagonism of TRPV1 had no effect on the exercise pressor reflex.

Supported by HL156594 and HL 156513

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.
Lipoprotein lipase activation is a novel vascular anti-contractile mechanism that is lost in aging
Authors: Wilson Emily , Costa Tiago , Fontes Milene , Waigi Emily , Townsend Paul , McQuail Joseph , Wenceslau Camilla , McCarthy Cameron
Published: May 2023

Increasing incidence of cardiovascular events with age can be attributed to the natural deterioration in organ function, and manifests through a range of vascular phenotypes that include, endothelial dysfunction, hypercontractility, stiffening and remodeling, inflammation, and oxidative stress. Given the aging global population, the identification and translation of novel mechanisms and therapeutics will be essential to increase longevity and prevent premature death and disability. Physiologically, perivascular adipose tissue (PVAT) is known to impact vasculature by exerting an anti-contractile effect mediated by the biosynthesis and liberation of a myriad of anti-contractile molecules (e.g., adipokines). However, this anti-contractile function declines with age and in related diseases. Therefore, our study aimed to restore the anti-contractile effect of PVAT in arteries from aged animals. Specifically, we predicted that increasing lipoprotein lipase (LPL) activity would reinstate the anti-contractile effect of PVAT on aged arteries. To assess this hypothesis, mesenteric resistance arteries (MRA), with (+) and without (-) PVAT, were isolated from male Fisher 344 rats aged 3 (3M) or 16 months (16M) and mounted on a wire myograph. Phenylephrine (PE) concentration-response curves were measured in the presence or absence of LPL activator, NO-1886 (Ibrolipim, 10uM). As expected, PVAT exerted significant anti-contractile effect in MRA, regardless of age [PE 100uM (%), 3M (-PVAT): 112.4±13.3 vs. 3M (+PVAT): 27.6±28.5 {Figure 1.a.} and 16M (-PVAT): 115.4±23.1 vs. 16M (+PVAT): 35.0±34.1 {Figure 1.b.}]. Contrary to our hypothesis, NO-1886 had no effect on the anti-contractile effect of PVAT in 3M or 16M rats [PE 100uM (%), 3M (+PVAT +vehicle): 30.0±34.3 vs. 3M (+PVAT +NO-1886): 47.9±29.8 {Figure 1.c.} and 16M (+PVAT +vehicle): 48.6±42.3 vs. 16M (+PVAT +NO-1886): 60.0±36.9 {Figure 1.d.}]. Surprisingly, we observed an effect of NO-1886 in MRA in the absence of PVAT. Specifically, NO-1886 significantly decreased phenylephrine-induced contraction in 3M rats, but not 16M rats [PE 100uM (%), 3M (-PVAT +vehicle): 112.4±13.3 vs. 3M (-PVAT +NO-1886): 37.8±22.2 {Figure 1.e.} and 16M (-PVAT +vehicle): 115.4±23.1 vs. 16M (-PVAT +NO-1886): 103.1±23.1 {Figure 1.f.}]. Overall, this suggests that LPL has an important physiological role in controlling vascular contraction and this novel anti-contractile mechanism of LPL diminishes with biological age.

Funding: NHLBI (R00HL151889), NIGMS (1P20GM103641 - Pilot Project), NIA (K01AG061263), UofSC SOM (Startup funds)

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.