bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-dose opioid analgesics (Morphine, Fentanyl, and Sufentanil) do not produce profound cardiovascular effects or reduce survival time in a rat model of traumatic hemorrhage
Authors: Marshall Stephanie , Marshall Stephanie , Ryan Kathy , Calderon Mariam , Connor Bryan , Hinojosa-Laborde Carmen , Klemcke Harold
Published: May 2023

Objective: To determine the impact of analgesic doses of opioids on cardiovascular function and survival time in a severe hemorrhage and extremity trauma rat model. Hypothesis: Using opioids for appropriate pain management, not sedation, will not exacerbate the pathophysiological shock process in a model of polytrauma. Background: Morphine has been doctrinally discarded for use in pain management following battlefield hemorrhage due to its effects on cardiovascular suppression. However, the effects of new opioids, Fentanyl and Sufentanil, on cardiovascular function have yet to be fully described. The current study was conducted to evaluate and compare effects of three opioid analgesics on cardiovascular function and survival after severe hemorrhage in conscious rats in the presence of extremity trauma (ET). Methods: Male rats (n=10/group) were randomly assigned to receive either 0.9% saline (S), 2.0 mg/kg morphine (M), 10 μg/kg fentanyl (F) or 1 μg/kg sufentanil (SuF). Two weeks prior to experimentation, rats were surgically implanted with a telemetry unit to measure mean arterial pressure (MAP) and heart rate (HR). A carotid catheter was then placed. After 24 hours, rats were anesthetized briefly to undergo soft tissue injury and fibula fracture. Rats were allowed to awaken, and 90 min later underwent a conscious hemorrhage (~50% of blood volume). At the end of hemorrhage, rats received one dose of either S, M, F, or SuF via the carotid catheter. Rats were observed for a maximum of 4 hr after the start of hemorrhage. Results: From 70 to 195 min after the end of hemorrhage, there was a significant (p≤0.04) decrease in the MAP of M rats relative to that of V rats, while SuF decreased MAP (p≤0.02) only at t=100, 220 and 240 min. There was no significant effect of treatment on HR (p=0.37) throughout the experiment. Neither survival times (p=0.88) nor percent survival (p=1.0) differed between treatment groups. Conclusions: At the analgesic dose previously shown to ameliorate behavioral indices of pain in rats, both M and SuF depressed blood pressure following severe traumatic hemorrhage. Despite this hypotensive effect, none of the opioids tested decreased survival time or survival rate.

Funding disclosure: Applied Pain Research Program, US Army Clinical and Rehabilitative Medicine/Joint Program Committee 8, and US Army Combat Casualty Care Research Program, US Army Medical Research and Development Command.

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.
Tools for studying enteroendocrine cell subtype development and physiology in zebrafish
Authors: Morash Margaret , Kay Richard , Wen Jia , Padilla-Mercado Gilberto , Ye Lihua , Reimann Frank , Gribble Fiona , Rawls John
Published: May 2023

Enteroendocrine cells (EECs) are sensory cells in the intestinal epithelium that respond to ingested nutrients and microbial products in the gut lumen by releasing over 30 different hormones and neurotransmitters. These signaling molecules travel throughout the body to influence a wide variety of metabolic functions, including glucose metabolism, satiety, and gut motility. EECs are typically divided into subtypes based on their predominant hormone. As enteroendocrine hormones have different and sometimes antagonistic metabolic effects, this subdivision enables fine-tuned control of metabolism in response to a variety of stimuli. While many aspects of EEC development and physiology have been defined, the mechanisms underlying EEC subtype-specific development and physiologic adaptations to diet and microbiota remain largely unknown. To investigate these questions, we recently established zebrafish as a model system for studying EEC physiology. The optical transparency of larval zebrafish enables live imaging to observe EEC adaptations in vivo and in real time. We used single-cell RNA sequencing to profile sorted intestinal epithelial cells from zebrafish larvae and identified secretory lineages including 7 EEC subtypes that we identified by expression of EEC hormones and transcription factors. Many zebrafish EEC subtypes we identified correlate with subtypes described in the mammalian small intestine, suggesting an evolutionary preserved role for EEC subtypes in regulating animal physiology. We also conducted LC-MS/MS peptidomics on EECs sorted from adult zebrafish intestine to reveal extensive homology in EEC hormone peptide sequence and post-translational processing. Using this information, we have begun to create transgenic lines to label and manipulate each of the EEC subtypes. For example, we identify a single EEC subtype that expresses genes encoding ghrelin, somatostatin, and glucose dependent insulinotropic peptides. Peptidomic analysis reveals striking conservation in their posttranslational processing including octanoylated and decanoylated isoforms of the ghrelin peptide. We have generated a transgenic line using the ghrelin gene and are using it to test how the number, distribution, and function of ghrelin positive cells vary as a function of diet and microbial colonization status. Establishment of a toolkit for zebrafish EEC subtype biology will provide an important alternative to the prevailing mammalian models and help unravel their unique developmental programs, physiologic functions, and adaptations to environmental variables.

NIH R01-DK093399 and the Gordon & Betty Moore 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.
Chronic sodium-glucose co-transporter 2 (SGLT2) inhibition reduces renal sympathetic nerve activation and fluid retention in rats with congestive heart failure
Authors: Zheng Hong , Liu Xuefei , Patel Tapan , Patel Kaushik
Published: May 2023

Congestive heart failure (CHF) is a pathophysiological state characterized by the activation of neurohumoral systems and sodium and water retention. Previously we have shown enhanced tonic renal sympathetic nerve activation in CHF increases the expression and functional activity of renal sodium-glucose co-transporter 2 (SGLT2). This study was to investigate the beneficial effects of chronic SGLT2 inhibition on renal sympathetic activity in CHF. Three weeks after coronary ligation surgery to induce CHF, Sprague Dawley rats were treated with SGLT2 inhibitor dapagliflozin (1mg/kg/day) via subcutaneous infusion for two weeks. Cardiac function, hemodynamic parameters, renal sympathetic nerve activity (both efferent and afferent activity), and renal excretory function were monitored. Compared with saline infusion, dapagliflozin significantly attenuated left ventricular end-diastolic pressure (13.6 ± 3.7 vs. 20.3 ± 3.9 mmHg, P<0.05) in rats with CHF. A slight decrease in mean arterial pressure was observed by telemetry in dapagliflozin-treated CHF rats. Dapagliflozin infusion increased urine volume (18.6 ± 3.1 vs. 9.2 ± 3.8 ml/day, P<0.05) and sodium excretion (4.8 ± 1.0 vs. 2.0 ± 0.6 mEq/day, P<0.05) in CHF rats. In CHF rats, dapagliflozin reduced urinary norepinephrine excretion (4.6 ± 0.4 vs. 8.3 ± 0.7 ug/day, P<0.05), basal renal sympathetic nerve activity (2.1 ± 0.3 vs. 3.8 ± 0.4 uV.s, P<0.05), and renal afferent sympathetic nerve activity (35.6 ± 5.7 vs. 58.4 ± 5.8 %Amax, P<0.05). These data suggest that chronic long-term treatment with SGLT2 inhibition exerts a potential protective effect on CHF through attenuating renal afferent and efferent sympathetic activity and consequent reduction in sodium retention.

Funded by NIH R01-DK-114663 & R01-DK-129311

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.
Beta-Adrenergic stimulation is necessary but not sufficient to promote CIH-induced Multiple Myeloma progression
Authors: Johnson Olivia , Vasileva Anastasiia , Vasilyev Mikhail , Lane Carter , Kalra Hardik , Jedlicka Charlie , Berschel Mackenzie , Tomasson Michael , Bates Melissa
Published: May 2023

Multiple myeloma (MM), a terminal cancer of bone marrow plasma cells, affects about 35,000 people yearly, and kills 13,000. The KaLwRij mouse model spontaneously develops pre-malignant myeloma disease (MGUS) and is receptive to myeloma development. In the C57BL/6 mouse model, chronic intermittent hypoxia allows lethal engraftment of malignant myeloma cells. Our central hypothesis is that myeloma susceptibility in both models is modulated by the sympathetic nervous system and beta-adrenergic receptor activation. 8 - week old C57BL/6 female mice were exposed to either propranolol, isoproterenol, or saline for 6 weeks. At week 2, mice were injected with either 5TGM1/GFP+ (MM) cells or saline. Heart rate and heart rate variability were collected using MouseOx and LabChart Pro to monitor expected drug effects. All animals were monitored for terminal paralysis. Bone marrow and spleen cells were harvested for qPCR analysis to quantify 5TGM1 cell proliferation. C57BL/6 mice did not have decreased survival when treated with isoproterenol, but propranolol was protective against CIH-induced MM susceptibility. Propranolol did not increase survival in KalwRij mice. In order for Multiple Myeloma to progress in the CIH mouse model, β2-adrenergic receptor activation is required but is not sufficient. This experiment can be used to understand the role of sympathetic nervous system stimulation and its contribution to MM engraftment and growth.

Supported by NIH 1R56HL152365.

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.
Automated analysis of smooth muscle calcium sparks in line-scan recordings of intact arteries
Authors: Nelapudi Nikitha , Boskind Madison , Williamson Grace , Juarez Rucha , Zhang Lubo , Blood Arlin , Wilson Christopher , Puglisi Jose , Wilson Sean
Published: May 2023

Activation of ryanodine receptors on the sarcoplasmic reticulum are well known to cause subcellular rapid Ca2+ events that are commonly referred to as Ca2+ sparks. These Ca2+ spark events regulate vascular reactivity through activation of potassium channels on the plasma membrane. Intracellular Ca2+ signals are commonly examined using fluorescent imaging approaches using high speed confocal microscopes. Over the past two decades, analysis of these events has advanced from visual observation and manual analysis by trained observers to more automated approaches. The purpose of the current study was to test whether fully automated approaches could accurately detect Ca2+ sparks in line-scan images and analyze spatial and temporal aspects to the events. This evaluation was addressed by re-analyzing a published “gold standard” dataset, where original analysis was performed through experimenter guided analysis of Ca2+ signals from recordings made in pulmonary arterial myocytes of en face arterial preparations. Ca2+ sparks were detected and analyzed automatically post-hoc using a customized Ca2+ spark analysis program, Sparklab 5.8. Increasing the threshold for detection led to incremental decreases in the percentage of cells with activity and the firing frequency. Raising the threshold also impacted the PPV, sensitivity and false discovery rate, which was examined through comparison to visually observed Ca2+ spark events. Interestingly, changing the threshold had little impact on spatial and temporal aspects of the Ca2+ spark events. Overall, automated Ca2+ spark detection and analysis with Sparklab 5.8 is expected to greatly improve experimental workflow and can be well optimized with low false discovery rates and reasonable levels of sensitivity.

NIH R01HL155295, R01HL149608

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.
Physiological Significance of Macula Densa Neuronal Nitric Oxide Synthase-1 in Renin Release and Renin-dependent Blood Pressure Maintenance
Authors: Liu Catherine , Parris Colby , Naeem Muhammad , Wang Lei
Published: May 2023

The role of macula densa nitric oxide synthase 1 (NOS1) in regulation of renin release is controversial. This study was conducted to further elucidate the role of macula densa NOS1 in renin release and blood pressure regulation in response to salt challenges and hemorrhagic shock.Tissue specific macula densa-NOS1 knockout (KO) and wild type (WT) mice were given low (0.1% NaCl) and high (1.4% NaCl) sodium diets or induced hemorrhagic shock by retro-orbital bleeding of 0.4 ml blood. Mean arterial pressure (MAP) was measured by radio-telemetry system. Plasma renin concentration (PRC) was determined by radioimmunoassay.PRCs were 496 ± 74 and 552 ± 68 ng/ml/hr in WT and KO mice fed a normal sodium diet, respectively. Low salt intake stimulated the renin release by about 220% in WT mice (PRC = 1364 ± 217 ng/ml/hr) compared to the level of normal salt diet, however, the stimulation was significantly blunted in KO mice (PRC = 688 ± 104 ng/ml/hr). High salt intake suppressed the PRC to the level of about 61% of PRC under normal salt diet. Deletion of macula densa-NOS1 further inhibited renin release to 43% of the levels of normal salt diet.Hemorrhagic shock induced about a 3-fold increase in PRC in WT mice, while only about 54% increase in the KO mice. The MAP values were significantly higher in WT mice than in KO mice during the first 6 hours following hemorrhagic shock. Thus, WT mice showed much quicker recovery in MAP than KO mice.Our study demonstrated that macula densa NOS1 plays an important role in mediating renin release. This mechanism is essential in maintaining blood pressure under hypovolemic situations such as hemorrhagic shock.

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.
Chronic unpredictable stress changes left ventricular geometry and activation of the inflammasome
Authors: Churillo Amelia , Freeburg Lisa , Stegmann Kyle , Doster James , Frambes Noelle , Crockett Alexia , Priviero Fernanda , Hollis Fiona , Wood Susan , Webb Clinton , Ryan Michael , Spinale Francis
Published: May 2023

Background: Psychosocial stress, particularly chronic unpredictable stress (CUS) has been identified as a risk factor for cardiovascular disease, but the effects of CUS on left ventricle (LV) function, geometry and systemic hemodynamics remains unclear. Moreover, whether and to what degree CUS activates intracellular formation of the inflammasome, including the NOD-LRR pyrin containing protein 3 (NLRP3) remains unknown. Accordingly, the central hypothesis of this project was that in a murine model of CUS, shifts in LV geometry and systemic hemodynamics would occur and be associated with the induction of NLRP3. Methods and Results: Mice (C57BL/6, 10wks of age, equal sex, n=16) were subjected to CUS for 4 weeks which entailed daily random stressors including tilted cage, wet bedding, and overnight light. Referent age and sex matched non CUS mice served as controls (n=16). LV function was assessed by high fidelity ultrasound and blood pressure measurements by tail cuff for both referent control and CUS mice. The changes in ambient heart rate (HR), LV end-systolic volume (LVEDV), and systolic blood pressure (SBP) were expressed as a function of referent control. All results are reported as mean ± SEM. While LV ejection fraction was equivalent between CUS and control groups (70 ± 3 vs. 67 ± 3%, respectively, p=0.48), HR trended higher (4.5 ± 3.1%, p=0.08), LVEDV was lower (-11 ± 5%, p=0.03) and SBP was elevated (12.1 ± 4.9%, p=0.04) - all indicative of heightened sympathetic tone. LV myocardial NLRP3 (rtPCR) was increased (1.47 ± 0.22 fold change, p=0.04) with CUS as was IL-1β (1.43 ± 0.20 fold change, p=0.05), a downstream cytokine activated by NLRP3. Conclusion: CUS, in and of itself, shifts LV geometry, causes mild hypertension and induction of the myocardial inflammasome- all of which would exacerbate/contribute to cardiovascular disease.

This work was supported in part by National Institutes of Health grant R01HL130972-01A1 (F.G.S.), R01HL5949 (F.G.S.), RO1DK132948 (C.W. & F.P.), R01 MH129798 (SKW) and P20GM109091 (F.H.) as well as a Merit Award from the Veterans Health Administration, BX000168-10A1 (F.G.S.), BX005320 (F.G.S.), BX002604 (M.J.R.), and VISN7 RDA (F.H.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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 5-HT1A agonist 8-OH-DPAT reverses the suppression of breathing but not swallowing caused by opioid administration in female rats
Authors: Frazure Michael , Morimoto In , Greene Clinton , Kimberly Iceman , Pitts Teresa
Published: May 2023

The objective of our study was to determine the role of 5-HT1A receptors in modulating breathing and swallowing following opioid administration. Our previous experiments in anesthetized male and female Sprague Dawley rats demonstrated that swallow is suppressed by the opioid buprenorphine, and that female rats are more susceptible to buprenorphine-induced respiratory arrest (71% mortality at 0.3 mg/kg) than male rats (100% survival at 0.3 mg/kg). We hypothesized that following buprenorphine administration, intravenous administration of the 5-HT1A agonist 8-OH-DPAT would restore breathing and swallowing. Experiments were performed in spontaneously breathing female Sprague Dawley rats anesthetized with sodium pentobarbital ( n = 7). Bipolar electromyography (EMG) wires were inserted into various muscles to measure breathing and airway protective behaviors. Swallow was stimulated by oral water infusion. Intravenous buprenorphine was administered in doses that yield respiratory arrest in female rats. Sustained apnea occurred in 86% of animals following buprenorphine administration (one animal resisted respiratory depression). 8-OH-DPAT was then administered to effect (100, 300, or 1,000 μg/kg i.v.). 8-OH-DPAT did not restore swallow, but breathing was recovered in 100% of animals (33% at 100 μg/kg, 50% at 300 μg/kg, and 17% at 1,000 μg/kg). This effect of 8-OH-DPAT was reversed by the 5-HT1A antagonist WAY 100635 (1 mg/kg i.v.), which abolished breathing in all animals. These results indicate that 5-HT1A agonists may be utilized to restore breathing following respiratory arrest, and that opioid-induced depression of breathing and swallowing are mediated by potentially separate mechanisms.

This work was supported by NIH grants HL 111215, HL 103415 and OT20D001983, the Craig H. Neilsen Foundation Pilot Research Grant 546714, Kentucky Spinal Cord and Head Injury Research Trust, and the Commonwealth of Kentucky Challenge for Excellence.

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.
Implementation and effects of low stakes quiz feedback on exam performance in a health professional program
Authors: Bains Mona , Goei Kathleen , Kaliski Debora
Published: May 2023

Introduction: The inclusion of interactive learning approaches in graduate education including mobile polling, game-based learning, physiology apps, eLearning activities and tablet use to supplement course content is an established means to improve student engagement. Strategies that continue to support learning asynchronously with the purpose of driving deeper critical thinking and reasoning has the potential to further advance course outcomes. The purpose of this investigation was to assess whether the incorporation of detailed asynchronous feedback to low stakes quizzes as an additional learning tool translates into improved exam performance in the Foundational Sciences. Methods: ExamSoft assessment data was collected across 2 semesters from 101 Doctor of Physical Therapy students enrolled in a Foundational Sciences course series encompassing cardiopulmonary, pediatrics and neuro blocked content. Exam performance was compared between 2 cohorts (non-feedback, n=53 and feedback group, n=48) following the implementation of detailed question feedback on low stakes semester quizzes with the second cohort. Exam performance on specific subject areas was also reviewed for select exam questions that directly aligned with quiz questions. Results: Independent samples t-test analyses indicated that learners in the feedback group demonstrated consistently improved exam performance for midterm (p < 0.001 for summer midterm and p < 0.01 for fall midterm) and final exams (p < 0.01 for both summer and fall final exams) across the 2 semesters when compared to the non-feedback group. Similar results were observed when specific exam questions were reviewed across physiology content areas. Vestibular physiology exam performance was significantly (p = 0.05) improved in the feedback group, while basal ganglia physiology showed a trend but was not significant. Pharmacology exam performance was significantly improved for the fall final exam (p < 0.001), but not for the fall midterm. Conclusions: Instructor tailored quiz question feedback, which requires student review to view the correct answer choice is an additional learning opportunity that results in improved course outcomes. This approach to providing feedback to low stakes assessments focuses the in-class time on new material because the quiz feedback can be reviewed asynchronously as needed by the learner. Using the learning management system quiz feedback feature provides a valuable strategy to further support learning outside of the classroom and provides an opportunity for students to synthesize and apply content at a deeper level.

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 Mechanical Stretch on Sex-Dependent Gene Expression by RNA Sequencing in Mouse Renal Endothelial Cells
Authors: Colvert C , Hawkins Kennedy , Oates Jim , DeLeon-Pennell Kristine , Van Beusecum Justin
Published: May 2023

Increased mechanical endothelial cell stretch contributes to the development of numerous cardiovascular and renal pathologies by orchestration of immune cell activation. While endothelial cells are not recognized as professional antigen presenting cells, they can express both major histocompatibility complexes (MHC) I and II. MHCs are essential to form part of the immunological synapse during antigen presentation to adaptive immune cells. The mechanisms by which increased endothelial cell stretch regulates renal endothelial antigen processing and presentation is unknown. We hypothesized that increased mechanical endothelial stretch promotes upregulation of key antigen processing and presentation genes in mouse renal endothelial cells (MRECs) in a sex-dependent manner. MRECs derived from both sexes underwent 5%, 10%, and 15% (1 Hz) uniaxial cyclical stretch for 48 hours. After stretch, RNA sequencing was performed and bioinformatic and pathway analysis was executed to determine potential inflammatory mechanisms of action. We found that 10% stretch induced downregulation in MHC and costimulatory genes ( H2-Da, H2-K1, H2-T23, H2-T24) and upregulation of antigen processing associated genes ( tap1, psmb2, psmb4, and psmb8) in male MRECs. Females undergoing 10% stretch exhibited inverse gene expression profiles with upregulation of MHC genes and downregulation of antigen processing and presentation genes. At 15% stretch, the sex-specific gene expression tendencies were inverse from 10% stretch. To understand the function of differential gene expression we performed gene ontology enrichment pathway analysis. Male MRECs undergoing 10% stretch exhibited an enrichment for renal and cardiovascular development processes and inflammatory processes including chemokine-mediated signaling and cytokine-mediated signaling. When we compared female MRECs at 10% stretch, we found enrichment for renal and cardiovascular development processes including endothelial cell migration, angiogenesis and glomerular vascular, kidney, and artery development. Interestingly, 10% mechanical stretch enriched pro-inflammatory processes including positive regulation of cell migration and leukocyte migration. These data provide novel insight into how mechanical stretch regulates key antigen processing and presentation pathways in renal endothelial cells in a stretch and sex-dependent manner.

This work was funded by MUSC Core Centers for Clinical Research Project Award to JPVB and Biomedical Laboratory Research and Development Service of the VA office of Research and Development Awards IK2BX003922 to KYDP and IK2BX005605 to JPVB.

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.
Cerebrovascular reactivity to carbon dioxide is not altered in otherwise healthy individuals six months post-concussion
Authors: Young Benjamin , Skow Rachel , Nandadeva Damsara , Garza Nicole , Stephens Brandi , Smith Scott , Lockette Warren , Fadel Paul
Published: May 2023

Introduction: Concussion, a form of mild traumatic brain injury (TBI), has an estimated annual incidence of 1-4 million cases in the US alone. Studies have documented impairments in cerebral vascular function following concussion which often coincide with other neurocognitive symptoms but, in some cases, persist despite symptom resolution. However, the majority of these studies were performed 3 months or less post-concussion. Therefore, we tested the hypothesis that cerebral vasodilator function is impaired in adults who had a concussion 6 months prior and are asymptomatic relative to healthy age- and sex- matched controls with no known history of concussion. Methods: Six adults (3 Male/3 Female, 26 ± 5 years) with a history of diagnosed concussion ~6 months prior to the study visit (average, 6 ± 1 months) and six controls (3 Male/3 Female, 28 ± 5 years) without a known history of concussion were recruited. Beat-to-beat blood pressure (finger photoplethysomography), middle cerebral artery blood velocity (MCAv; transcranial Doppler ultrasound) and partial pressure of end-tidal carbon dioxide (PETCO2; capnography) were measured continuously during two-minutes of quiet supine rest and throughout a rebreathing protocol designed to increase PETCO2 up to +15mmHg. Cerebral vascular conductance index (CVCi) was calculated as mean MCAv divided by mean arterial pressure (MAP) on a beat-to-beat basis. Cerebrovascular reactivity was assessed as the percent change in MCAv or CVCi at increasing levels of PETCO2 (Δ3,6,9,12,15 mmHg PETCO2) and the gain of the relationship between MCAv or CVCi and PETCO2. Results: Resting MAP (P=0.33), MCAv (control: 76 ± 6 cm/sec; TBI: 74 ± 8 cm/sec, P=0.82), and CVCi (control: 0.91 ± 0.08 cm/sec/mmHg; TBI: 0.86 ± 0.11 cm/sec/mmHg, P=0.72) were not different between groups. The CO2 rebreathing protocol increased MCAv and CVCi in both groups (main effect of time; P<0.001 for both). However, the percent change in MCAv and CVCi did not differ between control and TBI participants throughout the rebreathing protocol (Interaction, P=0.13 and P=0.26, respectively). Likewise, the MCAv (control: 3.5 ± 0.4 cm/sec/mmHg; TBI: 4.0 ± 0.6 cm/sec/mmHg, P=0.51) and CVCi (P=0.72) gains were not different between groups. Conclusion: These preliminary findings suggest that individuals six-months post-concussion who are asymptomatic do not exhibit impaired cerebral vasodilator function.

This project was supported by the Henry M Jackson Foundation HU0001-18-2-0016.

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 influence of early menopause on the hemodynamic responses to isometric exercise
Authors: Anselmo Miguel , Panigrahy Nisha , Teshome Soliana , Tahsin Chowdhury Tasnova , Stokes William , Lee Emma , Glazos Aline , Vanden Noven Marnie , Carter Jason , Keller-Ross Manda
Published: May 2023

Introduction: Menopause is linked to a heightened risk of hypertension and cardiovascular disease and early menopause (EM; age<46yrs) increases this risk. Exaggerated hemodynamic responses to exercise are associated with a greater risk of developing hypertension. Postmenopausal females demonstrate elevated blood pressure (BP) reactivity to isometric exercise compared with premenopausal females. It remains unknown whether these differences are attributable to menopause or age, and how EM influences reactivity. We hypothesized that females who experienced EM would have greater BP and heart rate (HR) reactivity to an isometric handgrip exercise (IHG) compared with typical-age-menopausal females (TAM; age 46-55yrs). Methods: Twenty-two postmenopausal females completed two study visits. Participants were divided into two age-matched groups: EM (n=11) and TAM (n=11). Visit 1 consisted of consent and health questionnaires. Visit 2 consisted of three maximal voluntary contractions of the left hand, three minutes of baseline rest, and IHG at 30% of maximal strength to failure; continuous measurements of HR and BP were collected. Results: Groups were similar in age (EM:60±3; TAM:60±3yrs; p=0.89), BMI (EM:26±1; TAM:24±1kg/m2; p=0.14), maximal voluntary contraction (EM:154±10; TAM:155±8N), but different in menopause duration (EM:20±2: TAM:12±2yrs; p=0.01). There were no differences in resting systolic BP (EM:125±6; TAM:124±4mmHg; p=0.97), diastolic BP (EM:79±3; TAM:75±3mmHg; p=0.45), mean BP (EM:94±3; TAM:92±3mmHg; p=0.79), and HR (EM:61±3; TAM:59±1bpm; p=0.46). During IHG, BP and HR increased similarly in both groups (p>0.05 for all). Conclusion: We have observed that neither duration of menopause nor age of menopause influence BP and HR reactivity during IHG. Although the sample size is low, these data suggest that greater hemodynamic reactivity to isometric exercise does not contribute to cardiovascular disease risk in EM females.

This study was supported by a NIH 1 K01 AG064038-01A1 (MLKR), UMN Grant-in-Aid (MLKR), F32HL160012 (EL), and NIH National Center for Advancing Translational Sciences grant UL1TR002494.

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.
Mixed Matrix Thermoset Casting with Thermoplastic Fused Filament Fabrication 3D Printing
Authors: Khanjar Saleh , Tyagi Prisha , Ajjarapu Kameswara Pavan Kuma , Kate Kunal
Published: May 2023

Thermoplastic materials are known for their toughness and elasticity, Thermosets are known for their stiffness and hardness. Multiple additive manufacturing processes can 3D Print thermoplastic or thermoset, but no current additive manufacturing technique can handle 3D printing both materials (thermoplastic & epoxy thermoset resins) simultaneously. Additionally, not enough studies highlight how materials would perform when a mixture of thermoset and thermoplastic are manufactured together. To address this issue in this work we are combining thermoplastics with the casting of thermoset. We printed tensile bars and 3-point bending bars with PLA with different infill percentages, Then infilled them with epoxy. The percentage increase on the toughness and elongation of the part by combining thermosets and thermoplastic was compared. Additive manufacturing of polymer composites infilled with epoxy thermosets has enormous potential for 3D printed construction structures. The application of Mixed Matrix Thermoset Casting within Thermoplastic Fused Filament Fabrication 3D Printing revealed promising results, addressing component efficiency and sustainability. Especially when virgin thermoplastic is replaced with recycled thermoplastic material and petroleum-based epoxies are replaced with bio-based epoxy. This work focused on engineering toughness and stiffness of mixed matrix composite material to match industrial requirements of construction materials.

self funded

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 contribution of intermediate conductance calcium-dependent potassium channels to hypothalamic vasopressin neuronal excitability
Authors: Shook Erin , Kirchner Matthew , Campos-Lira Elba , Stern Javier
Published: May 2023

Vasopressin (VP) magnocellular neurosecretory neurons of the supraoptic nucleus (SON) in the hypothalamus are critical regulators of renal water retention and vascular tone. VP neurons undergo detrimental plastic changes in cardiovascular diseases such as heart failure (HF), resulting in hyperexcitability and thus altered fluid/electrolyte balance. Hyperexcitability is caused in part by changes in intrinsic excitability mechanisms, including the slow afterhyperpolarization (sAHP), a phenomenon underlain by a calcium-dependent K+ current ( I sAHP). The sAHP is activated by Ca2+ and results in an efflux of K+ from the cell, hyperpolarizing it, and throttling firing. Importantly, we found that the sAHP is greatly inhibited in VP neurons from HF rats, contributing to increased neuronal excitability in this condition. While the features of the sAHP are well characterized, the identification of the channel underlying the I sAHP is unknown. Combining patch clamp electrophysiology and pharmacology in Wistar rats, we investigated Intermediate conductance Ca2+-dependent K+ (IK) channels as a potential candidate responsible for carrying the I sAHP. We generated and measured I sAHPs in voltage clamp via fixed steps of twenty spikes at twenty Hz and measured the the I sAHP as the resulting tail current at the end of the pulse. To account for rundown of the current over the recording period and for the pharmacological blocker’s slow mechanism of action, we measured I sAHPs every 60 seconds for at least 15 minutes. Bath application of TRAM-34 (2 μM) at 7 minutes, a specific IK channel blocker, failed to inhibit I sAHP peak amplitude or area (p > 0.05; n=36 SON neurons). We used biocytin-filled pipettes to identify neurons post hoc and run immunohistochemistry for oxytocin (OT) and VP to identify cell type within the SON. We found no significant difference in I sAHP amplitude or area between VP and OT cells under either control or TRAM-34 application. Taken together, our studies indicate that IK channels do not contribute to the I sAHP in SON neurosecretory neurons, despite robust IK expression in this region. Future studies will aim at identifying the role that IK channels play in SON, as well as targeting other potential K+ channel candidates for this

NHLBI F32 HL158172 (MKK) NHLBI HL090948 (JES) NINDS NS094640 (JES)

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.
Plasma derived exosomes from diabetic mice cause accumulation of neutral lipids in C2C12 myotubes
Authors: Pitzer Christopher , Paez Hector , Ferrandi Peter , Mohamed Junaith , Alway Stephen
Published: May 2023

Purpose: Skeletal muscle is the largest metabolically active organ in the body and a major site of glucose disposal. Ectopic neutral lipid accumulation in skeletal muscle is correlated with skeletal muscle insulin resistance. Exosomes are released by nearly every mammalian cell type and are found in almost all biofluids including the blood. Exosome biomolecular cargo is altered by multiple physiological stimuli. Exosomes found in the blood can readily enter skeletal muscle where their cargo regulates cellular metabolism. We hypothesized that exosomes derived from the serum of diabetic animals would alter expression of genes important for maintenance of lipid content in C2C12 myotubes, resulting in lipid accumulation. Methods: Exosomes were isolated from plasma of diabetic (Db/Db) and cage control mice using a commercially available exosome isolation reagent (exoQuick, System Biosciences Inc. Paolo Alto, CA) and resuspended in PBS. C2C12 myoblasts were grown to confluence and allowed to differentiate into myotubes for 5 days. Myotubes were treated with ARAC for 24 hours on day 3 of differentiation to remove proliferating myoblasts. Myotubes were incubated with plasma derived exosomes for 24 hours beginning on day 5 of differentiation. Oil Red O stain was performed to visualize lipid accumulation and then accumulated Oil Red O was eluted from washed myotubes. The eluent absorbance was quantified to determine intracellular lipid abundance. In a separate set of exosome exposed myotubes, qPCR was used to determine gene expression of genes important for lipid oxidation. Results: Oil Red O showed visible accumulation of lipids in myotubes exposed to exosomes from diabetic animals. Quantification of the Oil Red O elution showed a significant increase in neutral lipid presence in myotubes incubated with diabetic animal exosomes as compared to controls (32% increase, unpaired t-test P-value = 0.0004). qPCR showed no significant alterations in gene expression of FATP1, FATP4, ATGL, ACADM, or FASN. Conclusions: Together, these data show that exosomes from diabetic animals induce the accumulation of neutral lipids in C2C12 myotubes without altering expression of genes that maintain lipid content in these cells. This indicates a possibility that exosomes deliver neutral lipids to myotubes and that these lipids may be contained within exosomes and trafficked as cargo to the muscle.

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 circadian clock repressor Cry2 promotes adipogenesis by suppressing Wnt signaling via interaction with Per2
Authors: Li Weini , Xiong Xuekai , Kiperman Tali , Ma Ke
Published: May 2023

The circadian clock is driven by a transcriptional-translational feedback loop that elicits ~24 hour rhythms in behavior and physiology. The cell-autonomous clock exerts temporal regulation in adipocyte development and clock disruption leads to the development of obesity. There is current intense effort to identify clock-targeting interventions for metabolic disease therapy. Cryptochrome 2 (Cry2) is a circadian clock repressor, and it binds with Period proteins as a heterodimer complex to inhibit CLOCK/Bmal1-activated clock transcription that constitutes the negative feedback arm of the clock circuit. Our previous studies demonstrated that clock activator Bmal1 inhibits adipogenesis via the Wnt signaling pathway. To date, the role of Cry2 in adipogenic regulation remains unknown. Here we show that Cry2 inhibits adipogenesis and identify a critical residue that mediates interaction with Per2 required for this regulation. Cry2 transcript and protein are markedly induced during adipogenic differentiation. Via site-directed mutagenesis, we identified that Cysteine 432 within the lid domain of Cry2 protein is required for interaction with Per2, and a C432A mutant abolished this interaction. As a result, Cry2 repression activity of CLOCK/Bmal1-mediated transcription was abolished by the C432A mutant, as shown by Per2-luc reporter luciferase assay. Cry2 C432 mutation also led to elevated ubiquitination that accelerated protein degradation, an additional mechanism contributing to its loss of function. In 3T3L1 preadipocyte, we found that ectopic expression of Cry2 enhanced adipogenesis, whereas its loss-of-function suppressed adipocyte differentiation. In line with these findings, a Cry-stabilizing compound KL001 markedly augmented adipogenic differentiation. As compared to wild-type Cry2 effect on promoting adipogenesis, Cry2 C432A mutant largely abolished differentiation consistent with loss of repressive function in clock modulation. Mechanistically, we show that Cry2 induces adipogenesis via negative regulation of Wnt signaling pathway leading to inhibition of CCAAT/enhancer binding protein α (C/EBPα) expression. Together, our findings reveal a novel function of Cry2 in promoting adipocyte development via a critical residue involved in interaction with Per2. Our study thus provides a mechanistic basis for clock-targeting interventions to inhibit Cry2 activity for the treatment of obesity and its associated complications

This work is supported by NIDDK grants 1R01DK112794, 1R01DK130499 and AR-DMRI 2023 T2D Innovation Grant.

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 Epithelial Sodium Channel is a Zinc Sensitive Renal Sodium Reabsorption Pathway that Mediates Zinc Deficiency-induced Hypertension
Authors: McMichael Kelia , Wenegieme Tara-Yesomi , Waite Aston , Ume Adaku , Adams Danielle , Williams Clintoria
Published: May 2023

Background: Zinc deficiency (ZnD) is comorbid with many chronic diseases including kidney disease and diabetes. Individuals in these vulnerable populations have a higher prevalence of hypertension. Recently, we reported that ZnD induces hypertension by promoting renal Na+ reabsorption. However, the renal Na+ reabsorption mechanisms involved continue to be identified. The renal epithelial Na+ channel (ENaC) plays an essential role in regulating whole-body Na+ and water balance and is involved in hypertension. We hypothesize that ENaC is a Zn2+-sensitive channel that mediates ZnD-induced hypertension. Experimental Design: To establish the role of ENaC in ZnD-induced hypertension, WT C57Bl/6 mice were switched from a Zn2+ adequate to a Zn2+ deficient diet for 10 weeks. During weeks 9 and 10, mice were treated with benzamil, an ENaC inhibitor. Systolic blood pressure (BP) was monitored by tail-cuff plethysmography; Renal ENaC expression was examined by immunohistochemistry and Western blot. To authenticate the Zn2+ sensitivity of ENaC, mouse distal convoluted tubule cells (mDCT) were treated with a Zn2+ chelator (TPEN) or vehicle (DMSO) for 24 hours. A subset of TPEN-treated cellular monolayers were supplemented with Zn2+ for 24 hours to replete intracellular Zn2+. Cellular ENaC expression was examined by Western blot analysis. Results: B lood pressure: Compared to zinc adequate mice (101.4 mm Hg ± 4.225), zinc deficient mice had increased BP (154.6 mm Hg ± 2.422). However, benzamil treatment lowered BP (115.0 mm Hg ± 4.626) of zinc deficient mice. Immunohistochemistry: Next, Zn2+ effects on ENaC expression was examined. In zinc deficient mice, αENaC protein abundance significantly increased compared with zinc adequate mice. Western blot analysis: To directly investigate Zn2+ effects on ENaC expression, in vitro studies were performed using mDCT cells. Western blot analysis showed that TPEN-induced ZnD stimulated both αENaC and βENaC protein expression. Summary: Collectively, our findings reveal that (1) ENaC is a Zn2+ sensitive renal Na+ reabsorption pathway and (2) ENaC mediates ZnD-induced hypertension. Significance: Understanding the renal mechanisms by which Zn2+ regulates blood pressure may have an important therapeutic impact on hypertension.

Funding Source: AHA-16SDG27080009

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
High-fat loading abolishes sex differences in blood pressure (BP) responses to high-salt in Dahl rats
Authors: Godley Hannah , Dasinger John Henry , Cherian-Shaw Mary , Zamaro Aleksandra , Spires Denisha , Ilatovskaya Daria , Mattson David , Abias-Battad Justine , Sullivan Jennifer
Published: May 2023

There are numerous reports that male Dahl rats have greater increases in BP with a high-salt (HS) diet than females, yet women have been suggested to be more salt-sensitive than men. Since the typical Western diet consists of both HS and high-fat (HF), the goal of the present study was to test the hypothesis that HF loading and a combined HF/HS would abolish the protection observed in female Dahl rats vs. males. To test our hypothesis, 6 week old male and female Dahl rats were implanted with telemetry devices to continuously measure mean arterial BP; n=6. Rats were allowed to recover for one week followed by one week of baseline BP recording. Rats were then placed on a HF diet (60% kcal from lard; Bio-Serv) for 2 weeks followed by a HF/HS (4% salt; Bio-Serv) for an additional 2 weeks. Rats were placed in metabolic cages prior to starting HS and after 2 weeks to collect a 24 hour urine sample to measure urinary protein and albumin excretion. Glomerular filtration rate (GFR) was measured at the end of the study conscious freely moving animals using FITC-inulin elimination method. Baseline BP values were comparable between males (115±5 mmHg) and females (117±3 mmHg; p=0.67). BP increased during HF diet treatment, yet BP values remained similar in males and females (133±7 vs. 134±3 mmHg, respectively; p=0.93). Interestingly, females had a greater increase in BP on HF/HS vs. males that reached significance by the end of the study (146±7 vs. 160±6 mmHg, respectively; p=0.03). Despite this, urinary protein (185±23 vs. 94±19 mg/day; p=0.001) and albumin (142±22 vs. 56±13 mg/day; p=0.006) excretion were greater in males than in females. However, GFR was comparable between males and females (0.55 ± 0.03 vs. 0.45 ± 0.04 ml/min/100 g of body weight; p=0.07). In conclusion, female Dahl rats are not protected from HS diet when also challenged with HF, supporting our hypothesis that HF loading eliminates cardiovascular protection in females vs. males. However, males exhibited greater renal injury.

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.