bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial decrease in muscle activation induced by acute passive static stretching: a possible neuromuscular compartmentalization of the gastrocnemius muscle
Authors: Esposito Fabio , Toninelli Nicholas , Longo Stefano , Coratella Giuseppe , Rampichini Susanna , Limonta Eloisa , Borrelli Marta , Doria Christian , Padulo Johnny , Cè Emiliano
Published: May 2023

Recently, spatial adaptation of muscle excitability during sustained muscle voluntary contractions (MVC) up to fatigue has been reported, suggesting a functional muscle compartmentalization. Acute passive stretching (PS) can induce a reduction in surface electromyography (sEMG) amplitude; however, it is not clear whether PS may decrease motor-unit activity heterogeneously, similar to what occurs with fatigue. Therefore, the aim of the study was to evaluate possible heterogeneity in muscle activation following PS intervention in the gastrocnemius muscle. Thirty healthy men (age: 24±2 yrs., stature: 1.78±0.07 m, body mass: 77±6 kg) underwent a 5-min PS intervention (5 x 45s-on/15s-off cycles). Before (PRE), immediately after (POST) and after 5 (POST5) and 10 min (POST10), participants performed MVCs of the plantar-flexor muscles. Spatial muscle activation was recorded by means of high-density sEMG (HD-sEMG) in the gastrocnemius medialis and lateralis of the stretched and of the contralateral, non-stretched limb. The HD-sEMG root mean square (RMS) and its centroid were calculated. During stretching, the fascicle length and pennation angle (ultrasound approach) were measured for the proximal and distal portion of both muscles, together with the perceived level of discomfort (0-10 visual analogue scale). HD-sEMG RMS was reduced in POST, POST5 and POST10 in both gastrocnemius medialis (p<0.05 in all) and lateralis (p<0.05 in all) of the stretched limb, while the centroid shifted toward a more caudal direction (p<0.05). Interestingly, the same behaviour was found in the contralateral limb in POST for both muscles (both p<0.05). No differences were found in control. During stretching, no differences were found in fascicle length and pennation angle between the proximal and distal portion, whereas a higher discomfort was perceived in the distal portion of both muscles (p<0.05 in all). The uneven spatial decrease in muscle activation following acute PS suggests differences in neuromuscular organization of the gastrocnemius muscle. Possibly, a different discomfort perception between the proximal and distal portion could have induced a different inhibitory effect.

The study was funded by a grant of the Universitnà degli Studi di Milano

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.
A novel therapeutic Ang(1-7) analogue improves neurovascular function in mice with vascular contributions to cognitive impairment and dementia
Authors: Hoyer-Kimura Christina , Hoyer-Kimura Christina , Konhilas John , Pires Paulo , Banek Christopher , Dennis Melissa , Salcedo Victoria , Hay Meredith
Published: May 2023

Dynamic cerebral blood flow (CBF) regulation via neurovascular coupling (NVC) is essential to meet localized brain oxygen and nutrient demands. Cerebral microvascular dysfunction contributes to the pathogenesis of many types of dementias. Previous studies suggest that oxidative stress play a critical role in endothelial disfunction, cerebral microvascular impairments, and blunted NVC responses. Increased reactive oxidative species (ROS), inflammatory cytokines, and decreased brain blood flow contribute to the progression of both vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer's disease related dementia (ADRD).Our novel synthetic glycosylated Angiotensin-(1-7) derivative, PNA5, reverses cognitive deficits, inhibits brain ROS and inflammatory cytokine production, and limits microglial activation in our preclinical model of heart failure (HF)-induced VCID. We hypothesize that heart failure (HF) impairs cerebral vascular dilation and NVC, and that treatment with extended release PNA5 (PNA5ER) will improved cerebral vascular dilation and NVC. Adult male C57BL/6J mice (6-10/group) were subjected to HF via left anterior artery ligation or sham surgery 5 weeks prior to treatment with either 1) Vehicle (DMSO) or 2) 1.5mg PNA5ER (30uL of 50 mg/mL). Treatments were delivered subcutaneously at time= 3 weeks and again at t= 1 week prior to vascular evaluation and sacrifice. NVC was assessed using laser speckle imaging. Basal cerebral perfusion and NVC after somatosensory stimulation were assessed by laser speckle contrast imaging. NVC was calculated as a percent change in perfusion from baseline induced by stimulation. Basilar arteries were mounted on a wire myograph to assess cerebral vascular function. HF mice receiving vehicle treatment (n=2, mean= 4.41, Std Deviation=2.32) trend to have decreased NVC response compared to Sham (n=5, mean= 13.63, Std Deviation= 10.35), which may be rescued by PNA5ER (n=3, mean= 10.32, Std Deviation= 4.499). Endothelium-dependent dilation of basilar arteries, induced by cumulative concentrations of NS309 and 2-Methylthio-ADP, was impaired in HF compared to Sham mice; PNA5ER improved vasodilatory responses in the basilar artery.Our preliminary data suggest that PNA5ER protects against NVC impairments and improves basilar artery vasodilation in mice with HF-induced VCID, thereby potentially increasing the ability of the vasculature to meet the localized metabolic demands of the brain.

Supported by NIA

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.
Optogenetic activation of enkephalinergic neurons reveals excitatory effects in the respiratory rhythm generating network
Authors: Loginov Grigory , Baertsch Nathan
Published: May 2023

The primary cause of death during opioid overdose is respiratory depression. Opioid-induced respiratory depression (OIRD) is characterized by a pronounced decrease in the frequency and regularity of inspiratory efforts. This rhythm suppression is caused, in part, by activation of mu-opioid receptors (MORs) in the preBötzinger Compex (preBötC), a region in the ventral medulla that generates respiratory rhythm. In response to exogenous opioids, MOR-expressing preBötC neurons undergo modest hyperpolarization and glutamatergic synaptic transmission is suppressed via effects on presynaptic release. While MOR activation often leads to [LG1] destabilization and cessation of the inspiratory rhythm, under conditions of elevated network excitability it can also stabilize rhythm generation. In addition to MOR-expressing neurons, the preBötC also contains neurons that express enkephalin, an endogenous ligand for the MOR encoded by the Penk gene. Yet, little is known about how enkephalinergic neurons and endogenous MOR signaling affect respiratory rhythm generation. We hypothesized that activation of Penk neurons in the preBötC would suppress rhythm generation which under conditions of high excitability stabilizes network activity. To test this hypothesis, we optogenetically stimulated enkephalinergic preBötC neurons while recording respiratory activityin brainstem slices from PenkCre; Rosa26Chr2:YFP neonatal mice. To our surprise, optogenetic activation of Penk neurons strongly excited, rather than suppressed, the preBötC network. Specifically, brief 200-ms light pulses evoked inspiratory bursts with a high probability and low latency, consistent with the effects of activating glutamatergic preBötC neurons. Further, prolonged 30-Hz or continuous stimulations of Penk neurons increased the frequency of the inspiratory rhythm and these effects persisted following blockade of MORs with Naloxone. Based on the initial results, we predict that Penk neurons predominantly affect preBötC activity through glutamatergic signaling. The co-release of enkephalin may serve as a negative feedback mechanism that regulates the presynaptic release of glutamate to protect against network over-excitation. Understanding the role of endogenous MOR signaling in this vital respiratory network may inspire strategies to prevent respiratory depression during administration of exogenous opioids.

R00 HL145004 (Baertsch)

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.
Allelic modulation of mesenteric artery mechanical properties in young and adult APOE3 and APOE4 mice
Authors: Frantz Jana , Wagner Katherine , Dunlap Jazmin , Sharma Nikhil , Pathan Khalil , Gallo Jason , Gusek Brikena , Jones Carleton , Eckman Delrae
Published: May 2023

Previous studies from our lab have demonstrated age-related changes in vascular structure/function in posterior cerebral arteries (PCA) and left common carotid artery (CA) in male and female mice expressing human-ApoE targeted replacement of APOE3 (B6.129P2-Apoetm2(APOE*3)MaeN8) and APOE4 (B6.129P2-Apoetm3(APOE*4)Mae N8) (Taconic Labs). Therefore, we hypothesized that similar changes may be observed in the peripheral circulation. We isolated 3rd-order mesenteric arteries (MA) from young (Y, 3 to 4 mo) and adult (A, 7 to 10 mo), male and female mice expressing hPOE3 and hAPOE4. Mesenteric artery segments (5-8 mm in length) were isolated and cannulated on an arteriograph to assess vascular mechanical properties (lumen diameter (LD), wall thickness (WT), wall cross-sectional area (CSA), wall:lumen ratio (WL), distensibility (Dist), and stress/strain (SvS) under passive conditions (Ca2+-free Krebs + diltiazem) at intraluminal pressures ranging from 10-140 mmHg. Data were analyzed using two-way ANOVA, Student’s t-test, and analysis of nonlinear fit. Values were considered statistically different at P<0.05. Our data indicate that LD was greater in YE4 compared to YE3 mice (P<0.05), but was smaller in AE4 compared to AE3 mice (P<0.05). WT and WL was greater in YE3 mice compared to YE4 mice (P<0.05), but greater in AE4 compared to AE3 mice (P<0.05). While Dist was similar between YE3 and YE4 mice, AE4 mice exhibited less Dist than AE3 mice (P<0.05). Interestingly, distensibility increased between YE3 and AE3 mice (P<0.05), but was not significantly different between YE4 and AE4 mice. While compliance was similar between YE3 and YE4 mice, and similar between AE3 and AE4 mice, AE4 mice displayed decreased compliance compared to YE4 mice. No difference was seen between YE3 and AE3 mice. Wall stress was greater in YE4 mice compared to YE3 mice, but smaller in AE4 mice compared to AE3 mice (P<0.05), and an analogous pattern was observed in Einc for young and adult mice (P<0.05). These data indicate contrasting patterns of age-related vascular changes between allelotypes. Furthermore, these preliminary findings suggest that MA from A E4 mice exhibit a trend toward a hypertensive phenotype.

Support: ABRC/ADHS18-205211 (DME, CBJ), Arizona Alzheimer's Consortium (funded by the Arizona Department of Health Services, Contract No. CTR040636) and matching funds from Midwestern University (DME), Biomedical Sciences Program (JF, KW, JD, DME), Biomedical Sciences Start-up Funds (DME)

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.
Wheel running intensity effects on mice tendon mechanics
Authors: Valencia Miles , Ibáñez Rincon Apolo , Monroy Jenna , Garland Theodore , Horner Angela
Published: May 2023

Exercise has numerous effects on the musculoskeletal system, including muscle hypertrophy and tendon remodeling. Although exercise is well documented to affect tendon materials properties, the impacts of exercise intensity are less understood. To study the effects of exercise intensity on adult tendon, we used a line of mice artificially selected for high voluntary wheel running for over 90 generations (High Runner, HR). HR and control line mice were separated into wheel running and sedentary training groups at 9-weeks of age. Wheel activity was quantified using tachometers and collected weekly. After 9 weeks of exercise, mice were sacrificed and stored at -20 °C until the plantarflexor tendons were isolated for processing. Tendon cross-sectional area and length were measured in ImageJ. Tendons were marked with indelible ink for direct strain measurements and then were attached to an ergometer for sinusoidal and ramp-to-failure excursions. Force and lever displacement were recorded directly from the ergometer while actual tissue strain was obtained via high-speed videography. When analyzing our data with body mass as a covariate, our results suggest that exercise or linetype have no significant effect on tendon morphology; however, tendon length is significantly affected by the interaction of linetype and exercise. The interaction of exercise and linetype significantly affected yield and failure strain where wheel training increased strain in control mice and decreased strain in HR mice. Interestingly, wheel exercise and training intensity do not synergistically affect tendon material properties but result in varying changes. Total kilometers ran per day had an inverse relationship with yield and failure strain for control mice whereas HR mice showed no correlation for either; ultimately, no relationships with total kilometers ran per day were significant. Future studies should incorporate histological approaches to understand the tendon compositional changes leading to these variable responses.

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.
Epicatechin effect in an experimental pre-eclampsia model
Authors: Tufiño Cecilia , Soto Luis , Rodríguez Betzabel , Madrigal Damián , Bobadilla Rosa
Published: May 2023

Epicatechin effect in an experimental pre-eclampsia model Cecilia del Carmen Tufiño Martínez, Luis Jonathan Soto Ramírez, Betzabel Reyes Rodríguez, Damián Arturo Madrigal Aguilar, Rosa Amalia Bobadilla Lugo.Escuela Superior de Medicina del Instituto Politécnico Nacional (Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, 11340 Ciudad de México, CDMX)Preclampsia (PE) is a pregnancy specific disorder characterized by de novo development of hypertension and proteinuria. Both the pathophysiology and the treatment of this disease are not clearly established. Epicatechin is a natural product that has shown beneficial effects in several conditions including hypertensive as well as having recognized antioxidant capacity. The objective of this work was to evaluate if the Epicatechin can reduce blood pressure and vascular contractility in an experimental model of preclampsia. For this purpose, 250g ± 50 pregnant female Wistar rats at term were divided into control and with subrenal aortic coarctation or PE, and treated: a) Vehicle, b) epicatechin (10 mg/Kg/day) p.o. during the first two weeks or c) epicatechin (10 mg/Kg/day) p.o. during the last two weeks of gestation. Blood pressure and weight were recorded, and a glucose tolerance curve was performed. The animals were sacrificed at term (day 20) to assess vascular contractility in aortic rings using a conventional isolated organ device. The results showed that rats with PE have an increase in systolic blood pressure, blood glucose and vascular contractility (abdominal aorta) compared to rats with normal pregnancy. Epicatechin administration during the 1st and 2nd week decrease systolic blood pressure, and the contractile response to phenylephrine and angiotensin II in the abdominal segment but not in the thoracic segment of the aorta of preclamptic rats. We conclude that preventive epicatechin treatment improves systolic blood pressure increase observed in the preclampsia model. However, results suggest epicatechin effect is more relevant on resistance than conductance vessels.

Funding: Consejo Nacional de Ciencia y Tecnología (CONACyT)

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.
Chemosensory deficits and increased apneas in the 5XFAD mouse model of Alzheimer's disease
Authors: Sprenger Ryan , Romero Phinea , Ewald Andrea , Marino Kaitlyn , Gumnit Maia , McCann Erin , Ulland Tyler , Watters Jyoti , Baker Tracy
Published: May 2023

Alzheimer’s disease (AD) is a neurodegenerative disease commonly associated with aging. Along with a decline in cognition and memory, individuals with AD often have respiratory disturbances such as sleep apnea, insufficient ventilation during sleep, and shortness of breath. Mechanisms underlying respiratory dysfunction in AD are unknown but may involve chemosensory deficits since at least one chemosensitive region, the locus coeruleus, undergoes significant neurodegeneration during AD progression in humans. To test the hypothesis that chemoreflexes are impaired in a mouse model of AD, we measured the hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses using whole body plethysmography in 5XFAD mice as amyloid pathology progressed. We evaluated 2 timepoints of amyloid beta (Aß) pathology: early (4 months of age) and late (8 months of age). Compared to WT mice, 8-month-old male and female 5XFAD mice had a significantly reduced capacity to increase ventilation following challenge with 5% inspired CO2 (males: 5XFAD 99 ± 11% vs WT 168 ± 18%; females: 5XFAD 126 ± 12% vs. WT 212 ± 12%) or 5% inspired O2 (males: 5XFAD 141 ± 20% vs. WT 201 ± 20%; females: 5XFAD 75 ± 7.6% vs. WT 134 ± 12%). In addition, both male and female 5XFAD mice experienced significantly more apneic events (~120 apneas per/h) than their WT counterparts (~50 apneas/h) during presumptive sleep. Consistent with impaired ventilation, Aß plaques were abundant in medullary regions of the brainstem where both central chemosensors and rhythm generating neurons reside. Preliminary data suggest that chemoreflex dysfunction may emerge early in disease progression since a trend toward a reduced HCVR (5XFAD 133 ± 23% vs WT 206 ± 39%, combined sexes) was apparent in 4-month-old 5XFAD mice. Surprisingly, and contrary to findings at 8 months, preliminary data in 4-month-old 5XFAD mice indicate that the HVR may be slightly higher indicating that 5XFAD mice may be hypersensitive to hypoxia early in disease progression. Together, these data suggest that responses to ventilatory challenges become significantly disrupted by Aß pathology late in disease progression, deficits which may manifest early in disease and could promote disease progression. Results from our studies will identify the contributions of Aß deposition to respiratory dysfunction in 5XFAD mice, and may have implications for therapeutic interventions in individuals with AD.

NIH R01 HL142752, HL142752S1, and T32 AG000213

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.
Multi-omics Analyses Identify Galectin-1 as a Potential Novel Mediator of Heart Failure with Preserved Ejection Fraction in Mice and Humans
Authors: Wassenaar Jean , Smart Duncan , Fehrenbach Daniel , Dungan Matthew , Doran Amanda , Shuey Megan , Madhur Meena
Published: May 2023

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome where patients present with symptoms of volume overload despite having a normal systolic function. HFpEF is associated with elevation of inflammatory biomarkers, but the precise pathways leading to cardiac dysfunction is not known. In a deoxycorticosterone acetate (DOCA)-salt model of hypertension and HFpEF, we performed CITE-Seq analysis on total leukocytes isolated from the heart, which revealed significant differential gene expression primarily in the myeloid population. We then took the top 20 genes that were differentially expressed between myeloid cells from DOCA-salt vs sham treated mice and performed a genetic analysis called PrediXcan in Vanderbilt’s DNA databank, BioVU. Genetically predicted expression of two genes were associated with a HFpEF phenotype in humans. Of these, the gene encoding galectin 1, Lgals1, had the lowest p-value (0.02) and highest beta coefficient (0.32) corresponding to an odds ratio for HFpEF of 1.38. The role of galectin-1 in heart failure is unknown, we hypothesized that overexpression of Lgals1 exacerbates HFpEF. We found that siRNA knockdown of Lgals1 in bone marrow derived macrophages stimulated with lipoprotein saccharide and IFNγ, they expressed significantly more inflammatory genes such as IL-1α (p<0.0001), IL-6 (p=0.0219), iNOS (p=0.043), and TNFα (p=0.0031) using a 2-way ANOVA followed by Sidak’s multiple comparison test. Next, we explored the role of Lgals1 in the pathophysiology of HFpEF using Lgals1-/- mice. Surprisingly, despite both in vitro and in vivo data supporting a role of galectin-1 in HFpEF, Lgals1-/- mice did not show a significant difference in HFpEF phenotype (blood pressure, exercise tolerance, echocardiography, heart weight, or pulmonary congestion) after DOCA-salt treatment compared to littermate Lgals1+/+ controls in either males or females (p > 0.05 using Student’s t-test for all parameters measured, n=10-12). One hypothesis for this negative result is that Lgals1 is ubiquitously expressed, and a total body knockout may have compensatory mechanisms. We therefore created Lgals1 floxed mice and future studies will determine the effect of macrophage specific deletion of galectin-1 on HFpEF. In conclusion, while multi-omics approaches in mice and humans identify galectin-1 as a novel mediator of HFpEF, further studies in mice are needed to confirm its roles as a potential therapeutic target.

1R01HL161212-01A1, 19EIA34480023,,19IPLOI34760558, and 1T32HL144446-01

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.
Ibuprofen causes mitochondrial and proteasome dysfunction in murine hearts
Authors: Sule Rasheed , Tiwari Shuchita , Rivera Gabriela , Gomes Aldrin
Published: May 2023

Ibuprofen is one of the most commonly used compounds in the treatment of pain, fever, and inflammation. Despite its beneficial effects, the long-term use of ibuprofen has been previously associated with increased risks for cardiovascular diseases and all-cause mortality. Relatively little is known about the signaling pathways or mechanism(s) involved in ibuprofen’s ability to increase the risk of cardiovascular diseases. Very little is also known about sex-related differences with respect to ibuprofen. We investigated the effects of ibuprofen (100 mg/kg/day, equivalent to about a 500mg tablet/day for humans) on mouse hearts using proteomics. Proteomic results suggest that female mice hearts exposed to ibuprofen for 7 days had tenfold more changes than male mice hearts exposed to ibuprofen for 7 days. Both the expression and activity of β5i immunoproteasome was significantly increased in female mice heart relative to ibuprofen-treated male heart mice. Ibuprofen treatment altered mitochondrial function in both male and female mice. Ibuprofen also induced ROS generation and decreased mitochondrial membrane potential in both male and female mice. However, ibuprofen attenuated mitochondrial complex I activity only in female hearts. Several other signaling pathways were also altered only in female mouse hearts. This study found major ibuprofen-mediated selective effects on male and female mice hearts, with specific sex differences in mitochondrial and proteasome function in mice hearts.

NIEHS/Superfund P42 ES004699

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 bitter melon extract on cell survival and cell division markers in human metastatic breast cancer cells.
Authors: Bhetwal Bhupal , Remedi Marissa , Kopecek Kalie
Published: May 2023

Introduction: Bitter melon extract (BME) is known to exhibit cytotoxic effects on breast cancer cells (MCF-7). However, the molecular mechanisms by which BME exerts cytotoxic effects are not established. Aims: We aimed to investigate if BME exerts cytotoxic effects on MCF-7 cells via inhibiting cell division and cell proliferation pathways. We hypothesized that BME inhibits proliferation of MCF-7 cells by decreasing activities of mitogen-activated protein kinase (MAP kinase) & cyclins. The MAP kinase and cylcins play critical roles in mitotic cell division and cell survival respectively. Methods: Fresh bitter melons were purchased from an Asian grocery store and the extract (BME) was extracted, centrifuged, and filter sterilized. The MCF-7 cells were cultured in DMEM medium with 1% BME (v/v). After culturing cells for 48 hours, pictures of cultures were taken to confirm cytotoxic effects on cells. In our earlier experiments, BME induced decrease in cell viability was also confirmed using Trypan blue exclusion and MTT assays. The cells were harvested and changes in the protein expression of Cyclin B1 and phosphorylated MAP kinase (P42/44, which is also known as Erk 1/2) were determined using anti-Cyclin B1 and anti- Phospho- Thr202/Tyr204 Erk1/2 antibodies in the western blotting. Results & Discussion: BME exerted cytotoxic effects on MCF-cells (N=4). BME almost completely wiped out the expression of cyclin B1 protein and phospho-Erk 1/2 (N=3 with duplicate gels). However, total Erk and GAPDH protein expressions were not affected by the BME treatment (N=3).The data together supports our hypothesis. In the future, we will be running more sets of experiments to confirm our findings.

FRD-MUCOM. All authors contributed equally to this work.

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.
Multi-omic analysis of the cardiac cellulome defines a vascular contribution to cardiac diastolic dysfunction in obesity
Authors: Bender Shawn , Dona Malathi , Hsu Ian , Meuth Alex , Brown Scott , Bailey Chastidy , Aragonez Christian , Chandrasekar Bysani , Martinez-Lemus Luis , DeMarco Vincent , Grisanti Laurel , Jaffe Iris , Pinto Alex
Published: May 2023

Coronary microvascular dysfunction (CMD) is associated with cardiac dysfunction and predictive of cardiac mortality in obesity, especially in females. Emerging evidence suggests development of heart failure with preserved ejection fraction in females with CMD and that mineralocorticoid receptor (MR) antagonism may be more efficacious in obese female, versus male, HFpEF patients. Accordingly, we examined the hypothesis that smooth muscle cell (SMC)-specific MR deletion prevents obesity-associated coronary and cardiac diastolic dysfunction in females. Obesity was induced in female mice via western diet (WD) feeding alongside littermates fed standard diet. Initial studies revealed that global MR blockade with spironolactone prevented impaired coronary vasodilation and diastolic dysfunction in obese females. Importantly, specific deletion of SMC-MR similarly prevented obesity-associated coronary and cardiac dysfunction. Cardiac gene expression profiling suggested reduced cardiac inflammation in WD-fed mice with SMC-MR deletion independent of blood pressure, aortic stiffening, and cardiac hypertrophy. Further mechanistic studies utilizing single-cell RNA sequencing of non-cardiomyocyte cell populations revealed novel impacts of SMC-MR deletion on the cardiac cellulome in obese mice. Specifically, WD feeding induced inflammatory gene signatures in multiple non-myocyte populations (B/T cells, macrophages, and endothelium), independent of cardiac fibrosis, that was prevented by SMC-MR deletion. Further, SMC-MR deletion induced a basal reduction in cardiac mast cells and prevented WD-induced cardiac pro-inflammatory chemokine expression and leukocyte recruitment. These data reveal a central role for SMC-MR signaling broadly impacting the cardiac cellulome and underlying obesity-associated coronary and cardiac dysfunction thus supporting the emerging paradigm of a vascular origin of cardiac dysfunction in obesity.

Supported by NIH R01 HL136386 (Bender), NIH R01 HL119290 (Jaffe), the University of Missouri Research Core Facilities Grant Program (Bender), NHMRC Ideas Grant GNT1188503 (Pinto), VA Merit I01 BX004220 and RCS IK2 6004016 (Chandrasekar). The work was also supported by resources and the use of facilities at the Harry S. Truman Memorial Veterans Hospital in Columbia, MO.

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.
Antioxidant Flavonoid Diosmetin Is Cardio-Protective in a Rat model of Myocardial Infarction induced by Beta 1-Adrenergic Receptor Activation
Authors: Ahmad Taseer , Khan Taous , Kirabo Annet , Shah Abdul
Published: May 2023

Myocardial infarction (MI), is a common and life-threatening manifestation of ischemic heart diseases. The most important risk factor for MI is hypertension. Flavonoids have been found to be efficacious in ischemic heart diseases by alleviating oxidative stress and beta-1 adrenergic activation but the mechanistic link is not clear. We hypothesized that antioxidant flavonoid diosmetin is cardio-protective in a rat model of MI induced by beta 1-adrenergic receptor activation. To test this hypothesis, we evaluated the cardioprotective potential of diosmetin on isoproterenol-induced myocardial infarction in rats by performing lead II electrocardiography (ECG), cardiac biomarkers including troponin I and creatinine kinase by using biolyzer 100, as well as histopathological analysis. We found that diosmetin (1 and 3 mg/kg) attenuated isoproterenol-induced elevation in T-wave and deep Q-wave on the ECG, as well as heart to body weight ratio (0.53 ± 0.01 vs. 0.34 ± 0.02, p< 0.001), and infarction size (55 ± 3.16 vs 13.33 ± 1.83 p< 0.001). In addition, pretreatment with diosmetin attenuated the isoproterenol-induced increase in serum troponin I (0.68 ± 0.012 vs 0.310 ± 0.0115, p< 0.001). These results demonstrate that flavonoid diosmetin may provide therapeutic benefit in myocardial infarction.

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.
Dipsogenic Role of Angiotensin II during Fear Memory Retrieval
Authors: Iyer Laxmi , Yu Zhe , Paronett Elizabeth , Swiercz Adam , Marvar Paul
Published: May 2023

Motivational cues of thirst, sleep, and hunger impact memory and behavioral responses across species. Brain angiotensin II (AngII) is a potent thirst-producing peptide, where prior research demonstrated that angiotensin receptor blocker affects conditioned fear memory. We therefore hypothesized that acute water deprivation (WD) concurrent with angiotensin receptor blockage increases endogenous AngII levels and contributes to fear memory retrieval plasticity.C57BL/6J male mice underwent both auditory and contextual fear conditioning and received a single retrieval tone to initiate memory recall. During this time, mice were water restricted (24hrs) or ad-libitum in the presence/ absence of the angiotensin type1 receptor antagonist losartan (10mg/kg i.p.) given post fear memory retrieval. RT-qPCR, mass spectrometry, IHC, and ELISAs were performed to analyze specific synaptic plasticity and memory markers.Mice, which underwent WD during auditory memory retrieval, showed a significant reduction in freezing behavior in comparison to the non-WD controls during long-term memory (LTM) tests at 24hrs (p= 0.0019, n=12) and 1 week (p = 0.002, n=12). No difference in freezing response was observed in losartan-WD mice. Fear memory tests, after concurrent WD and contextual fear memory retrieval, showed no difference in freezing behavior between non-WD controls and WD with and without losartan (n=12). There was no significant difference in the baseline anxiety and locomotion behavior after water restriction. Following water deprivation, mass spectrometry revealed an elevated level of AngII peptide in the Subfornical region (SFO), an area essential for fluid regulation. The mRNA expression of RAS and synaptic plasticity genes - Agtr1, Agt and Bdnf (p<0.01, n=6) - were also significantly up-regulated only in WD saline mice. WD mice also had increased circulating aldosterone and angiotensin II (p<0.05, n=7) levels.Our findings indicate that elevated angiotensin II as a result of WD, reduced LTM, only during auditory fear memory reconsolidation, while altering the expression of specific RAS genes in SFO. Peripheral administration of losartan however blocked this effect. We propose that endogenous AngII as a dispogenic neuromodulator affects memory in a physiological state-dependent manner.

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.
Role of Rho kinase & Rhotekin in the bitter melon extract mediated cytotoxic effects on human metastatic breast cancer cells
Authors: Bhetwal Bhupal , Miller Claire , Kotlinski Henry , George Marie , Bleeke Jadyn
Published: May 2023

Introduction: Bitter melon extract (BME) is known to exhibit cytotoxic effects on breast cancer cells (MCF-7). However, the molecular mechanisms by which BME exerts cytotoxic effects are not established. Aims: We aimed to investigate if BME exerts cytotoxic effects on MCF-7 cells via inhibiting Rho kinase (ROK) activity and Rhotekin expression. Both TOK and Rhotekin mediate several cellular processes such as cell division, attachment, migration etc. We hypothesized that BME exerts cytotoxic effects on MCF-7 cells by decreasing ROK activity and Rhotekin expression. Methods: Fresh bitter melons were purchased from an Asian grocery store and the extract (BME) was extracted, centrifuged, and filter sterilized. The MCF-7 cells were cultured in DMEM medium with 1% BME (v/v). After culturing cells for 48 hours, pictures of cultures were taken to confirm cytotoxic effects on cells. In our earlier experiments, BME induced decrease in cell viability was also confirmed using Trypan blue exclusion and MTT assays. The cells were harvested and changes in the protein expression of phospho-MYPT1 and Rhotekin were determined using anti-phospho-MYPT1 and anti- Rhotekin antibodies in the western blotting. Since ROK directly phosphorylates MYPT1, reduced expression of phospho-MYPT1 would indirectly suggest reduced ROK activity. Similarly, reduced expression of rhotekin is a downstream mediator of ROK activation pathway and reduced level of rhotekin would also contribute to the reduced viability of cells. Results & Discussion: BME exerted cytotoxic effects on MCF-cells (N=4). However, BME did not decrease expression levels of phospho-Thr 853-MYPT1 (N=3, duplicate gels). Also, BME did not affect Rhotekin expression (N=3, duplicate gels). Three different loading control proteins (actin, myosin lighta chain, and GAPDH) were used and none of them were affected by the BME. The data together rejects our hypothesis. In the future, we will be running more sets of experiments to confirm our findings.

FRD-MUCOM. All authors contributed equally to this work.

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.
Pain and Plasticity: Spike Sorting Based Approach for Characterizing the Neural Circuitry Mediating Nociceptive Sensitization of the Defensive Strike Response in M. sexta
Authors: Valtierra Christian
Published: May 2023

Nociception is the neural process of encoding and processing noxious stimuli; this sensation is transduced by specialized sensory neurons called nociceptors. Activation of nociceptors typically evoke so called “nocifensive behavioral responses,” that are generally aimed at decreasing exposure to the noxious stimulus. Intense activation of nociceptors can result in long lasting changes in the nervous system, as well as a subsequent decrease in the threshold for perceiving and acting upon stimuli as if it were harmful—this persistent change in the organism is nociceptive sensitization. The hornworm, Manduca sexta, displays rapid defensive “striking” behavior that accurately targets the cite of noxious stimulation of the abdominal body wall. Nociceptive sensitization of the defensive strike response has been induced behaviorally and recapitulated in vitro through extracellular electrophysiology, where it appears to be encoded by an increase in the firing frequency occurring within the central nervous system, rather than changes in peripheral nociceptor signaling. The current model proposed by Tabuena et al. (2017), argues that central neural alterations are responsible for the neural correlate of nociceptive sensitization (Tabuena et al., 2017), rather than changes in spiking activity of the primary sensory neurons. While the changes in firing frequency centrally are undisputed, relegating sensitization to the CNS alone may be overly simplistic, as the model is based on the comparison of threshold crossings of purported multiunit activity, rather than of single cell activity of known populations of sensory and/or higher order neurons. Moreover, studies in the vertebrate and invertebrate literature alike have reported retrograde sensitization of primary nociceptors (Parada et al., 2003; Xie et al., 2022; Babcock et al., 2000), mediated by inflammatory signals from the cite of injury, thus complicating the question of central versus peripheral sensitization. Therefore, it is worth re-examining the possibility of presynaptic plasticity as an added contribution to nociceptive sensitization. In this work, we propose leveraging available neuroanatomical data to re-analyze the Tabuena et al. dataset, by performing spike sorting and spike train analyses to tease apart the signals originating from the peripheral sensory neurons to obtain input/output relationships between the identified sensory units and VNC spiking during stimulation. Distinguishing the nociceptor and tracking its stimulus dependent firing is expected to elucidate the contribution of nociceptor activity in nociceptive sensitization.

Genentech Scholars Foundation

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.
Skeletal muscle regeneration at different phases of the menstrual cycle
Authors: Ahmadi Mohadeseh , Pfeifer Brandon , Shimizu Krista , Hunter Werner , Altuhov Stepan , Nielsen Madeline , Hyldahl Robert
Published: May 2023

INTRODUCTION: The effect of estrogen on muscle function and recovery from damage has been studied, but the effects of estrogen fluctuations during the menstrual cycle on muscle regeneration remain inconclusive. PURPOSE: The purpose of this study was to examine the effects of menstrual cycle phases on muscle regeneration after electrically stimulated muscle damage. We hypothesized that muscle damage during the late follicular (LF) phase results in better muscle regeneration as compared to muscle damage during the early follicular (EF) phase. METHODS: 23 premenopausal females (21.3±2 yrs) were recruited and split into two groups, EF and LF. After menstrual cycle tracking and phase confirmation, subjects underwent 200 electrically stimulated eccentric muscle contractions one week after providing a muscle biopsy. 7 days after inducing muscle damage, the subjects reported to give a final biopsy. Sections from muscle samples were stained for markers of laminin, dystrophin, satellite cells (SCs; Pax7), nuclei, total macrophages (CD68), and anti-inflammatory macrophages (CD206/CD68). Data for SCs, and %CD206+CD68+ cells are presented as mean±SD, and damaged fibers and CD206+CD68+ cells/fiber are presented as median±interquartile range. RESULTS: Electrical stimulation caused muscle fiber necrosis (0.005±0.018 damaged fiber/fiber, p=0.0002) as measured by the laminin-containing and dystrophin-deficient fibers. There was no difference between EF and LF groups for the number of damaged fibers (p=0.055) Muscle damage resulted in ~200% increase in the total number of CD68+ macrophages (p=0.008), and ~ 40% increase in the number of SCs (p=0.001) in both groups. However, there was no significant difference between EF and LF groups for the change in total macrophages per fiber (p=0.07) or SCs/fiber (p=0.25) in response to electrically stimulated muscle damage. Anti-inflammatory macrophages increased by about 104%±127 in EF and 240%±390 in LF group, but the difference between groups was not significant (p=0.39). A comparison of the proportion of anti-inflammatory macrophages per total macrophages before and one week after muscle damage did not show any time effect (p=0.25), which could indicate the regenerative and anti-inflammatory state of skeletal muscle one week after damage. CONCLUSION: Contrary to our hypothesis, our data indicate that skeletal muscle regeneration is not affected by different phases of the menstrual cycle. However, this finding is limited to only some of the markers of regeneration one week after muscle damage.

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.
Oxidative stress-related impairment of endothelial function in uncomplicated obesity
Authors: Kovarik Jack , Holwerda Seth
Published: May 2023

Purpose: Visceral obesity is associated with vascular oxidative stress and development of hypertension. Therefore, we tested the hypothesis that suppression of vascular oxidative stress in adults with visceral obesity would improve endothelium-dependent dilation. Methods: IV infusion of a water-soluble antioxidant (ascorbic acid) was performed in 15 middle-age obese adults (3 men/12 women) without diabetes or hypertension in a placebo-controlled, double-blinded, crossover study design. Ascorbic acid was infused at 0.06g/kg fat free mass in 100 ml saline at 5 mL/min over 20 min (bolus) followed by a drip infusion at 0.02 g/kg fat-free mass in 30 ml saline at 0.5 mL/min over 60 min. Endothelium-dependent dilation was assessed via brachial artery flow-mediated dilation (FMD) and expressed as % increase in diameter from baseline before forearm occlusion. Results: Android fat distribution in the visceral cavity (VAT%) was 39 ± 10% and body mass index (BMI) was 37 ± 6 kg/m2. IV infusion significantly increased plasma ascorbic acid concentrations (Baseline: 42 ± 2 vs. Bolus: 66 ± 6 vs. End: 62 ± 4 μmol/L, P<0.001). Compared with baseline, bolus infusion of ascorbic acid significantly increased FMD (Baseline: 5.8 ± 2.5 vs. Bolus: 9.0 ± 4.0 vs. End: 8.0 ± 4.2 %, P=0.01), which remained after statistically adjusting for the stimulus (shear rate area under the curve) via analysis of covariance (P=0.04). No significant change in FMD was observed following placebo (saline) during a separate study visit (Baseline: 8.0 ± 4.4 vs. Bolus: 8.3 ± 3.9 vs. End: 8.6 ± 2.9 %, P=0.86). Conclusions: These preliminary findings suggest that acute elevations in plasma ascorbic acid concentrations improve endothelium-dependent dilation in middle-aged adults with visceral obesity. Future studies should target mechanisms by which mediators of oxidative stress in obesity (e.g., hyperlipidemia, hyperinsulinemia) inhibit nitric oxide-mediated vasodilation.

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

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The role of contraction mode in determining exercise tolerance, torque-duration relationship, and neuromuscular fatigue
Authors: Ducrocq Guillaume , Al-Assad Simon , Nabil Kouzkouz , Hureau Thomas
Published: May 2023

Purpose: Critical torque (CT) and work done above it (Wʹ) are key predictors of exercise performance associated with neuromuscular fatigue. The aim of the present study was to understand the role of the metabolic cost of exercise in determining exercise tolerance, CT and Wʹ and the mechanisms of neuromuscular fatigue. Methods: Twelve subjects performed four knee extension time-trials (6, 8, 10, and 12-minutes) using eccentric, isometric, or concentric contractions (3s-on/2s-off at 90° or 30°/s) to modulate the metabolic cost of exercise. Exercise performance was quantified by total impulse and mean torque. CT and Wʹ were determined using the linear relationship between total impulse and contraction time. Cardiometabolic, neuromuscular, and ventilatory responses were quantified. Neuromuscular function was evaluated by maximal voluntary contraction, resting potentiated single/doublet electrical stimulations, and superimposed single electrical stimulation to quantify neuromuscular, peripheral, and central fatigue, respectively. Results: Compared to isometric exercise, total impulse (+36±21%; P<0.001), CT (+27±30%; P<0.001), and Wʹ (+67±99%; P<0.001) were increased during eccentric exercise whereas total impulse (-25±7%; P<0.001), critical torque (-26±15%; P<0.001) and Wʹ (-18±19%; P<0.001) were reduced in concentric exercise. Conversely, the metabolic response and the degree of peripheral fatigue were reduced during eccentric exercise whereas they were increased during concentric exercise. CT was negatively associated with oxygen consumption gain ( R2=0.636; P<0.001) and Wʹ was negatively associated with rates of neuromuscular and peripheral fatigue indices ( R2=[0.252-0.880]; P<0.001). Conclusion: The contraction mode influenced both CT and Wʹ, and consequently exercise tolerance, indicating that the metabolic cost of contraction played a key role.

This work was supported by the University of Strasbourg Initiative of Excellence (2021-022-10 and ANR-10-IDEX-0002-02)

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.