bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of ECM and mechanical strain on vascular cell plasticity
Authors: Brady Travis , Santhanam Lakshmi , Gerecht Sharon
Published: May 2023

Introduction: Depending on surrounding cell types, substrate mechanics, and chemical agonists, vascular smooth muscle cells (VSMCs) alternate between a contractile and synthetic phenotype. While endothelial cells (ECs) do not modulate their phenotype in this way, their behavior is highly dependent on location within the body. These variations are part of healthy vascular function, but improper phenotype has been implicated in cardiovascular disease. Atherosclerotic lesions, for example, have been found to be high in dedifferentiated, synthetic VSMCs as well as endothelial cells that have undergone endothelial to mesenchymal transition (EndMT). The overall goal of this project is to understand the effect of cross-talk between ECM and mechanical strain on vascular cell plasticity during aging. Materials and Methods: Mouse aortic smooth muscle cells (maSMCs) were isolated from C57Bl6 mice at less than 3 months (young), 6 to 10 months of age (middle-aged; MA), or greater than 15 months of age (old). Cells were then seeded onto dye-quenched (DQ) collagen type I (Col-I) substrate and measured for gain of fluorescent signal over 3 days. Human aortic endothelial cells (HAECs) were seeded onto glass cover slips or fibronectin coated PDMS chambers. Cells were further treated with or without TGF-β2 with daily media changes over 3 days. IF images were captured with a Leica Confocal microscope and quantification was performed using ImageJ. Results: ECs cultured on glass or treated with TGF-β2 show increased expression of SM22α and decreased expression of VECAD. Physiological strain (10%) did not cause changes in expression relative to static (0%). Mouse aortic SMCs isolated from older mice had significantly decreased rates of Col-I cleavage. Conclusions: maSMCs from older mice have lower Col-I turnover than their younger counterparts. This is consistent with bulk tissue behavior, as it is well known that relative collagen levels increase in the elastic vasculature as we age. HAECs on stiff substrates are more likely to show signs of EndMT – consistent with other studies. The addition of agonists such as TGF-β2 can reproduce this behavior in cells cultured on soft substrates.

NASEM Ford Foundation Pre-Doctoral Fellowship and NHBLI grant R01HL148112 01 (L.S.)

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.
Deletion of myostatin alters obesity-induced estrogen metabolism in skeletal muscle
Authors: Rosewater Cody , Guilfoyle-Speese Andrew , Padget Caleb , Mintz James , Brown Zach , Fulton David , Stepp David
Published: May 2023

Objective: Obesity alters sex hormone balance in males, resulting in low testosterone and altered metabolism of estrogen, independent risk factors for cardiometabolic dysfunction. The basis of these alterations and how they are impacted by factors that improve cardiometabolic outcomes in obesity are unknown. Methods: Control and obese mice ( db/db) with or without deletion of myostatin to induce hypermuscularity were used. Mice were analyzed for plasma sex hormones via mass-spectrometry with or without 10mg/kg/day fadrazole to inhibit aromatase. Quantitative PCR was used to measure aromatase along with cytochrome P450 enzymes involved in estrogen metabolism in the liver, skeletal muscle, and visceral adipose tissue. HEK293a cells were treated with myostatin in vitro and enzyme levels assessed. Results: Obesity decreased plasma testosterone 30% and increased estrogen 20% with no change in gonadal weight. Deletion of myostatin increased muscle mass >30% and resulted in a reduction in estrogen levels without a parallel increase in androgens in obese mice. Inhibition of aromatase restores estrogen levels indicating the excess estrogen in obesity is derived from testosterone conversion. Since estrogen was lowered without increasing testosterone and estrogen metabolism must be increased. Aromatase was increased in obesity but unaffected by changes in muscle mass. CYP1B1, an enzyme that converts estradiol to hydroxy estrogens, showed 2.5 fold expression in obese skeletal muscle, which is improved in the absence of myostatin, with no change in other P450s involved in estrogen metabolism. Moreover, changes in P450 enzymes in liver or fat were either absent or changed directionally opposite to observed hormone changes. In HEK cells, treatment with myostatin recapitulated changes in CYP1B1 expression seen in vitro, suggesting a direct link between the myokine and sex hormone metabolism by skeletal muscle. Conclusion: In summary, obesity causes a shift in sex hormone levels to estrogen production, which is improved by myostatin deletion, without restoration of androgens. A potential mechanism responsible could be altered estrogen catabolism, leading to decreased estrogen levels without the restoration of androgen levels. Together, these data suggest CYP1B1 drives the conversion of estrogen to hydroxestrogens, which are known pro-oxidant and pro-lipidemic influences that may contribute to cardiometabolic disease. Whether targeting CYP1B1 improves cardiometabolic function in obesity remains to be determined.

D.W. Stepp and D.J. Fulton are supported by NIH 1R01HL147159

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The Impact of a Vegan Diet on Cardiovascular Disease Risk in Men and Women Through the Gut Microbiome
Authors: Lee Amanda , Uno Jennifer
Published: May 2023

Studies highlight many benefits of a vegan diet on the composition of the gut microbiome, however little is known how and if these changes contribute to heart health. Trimethylamine (TMA) is a metabolic product produced from the breakdown of choline and L-Carnitine both found abundantly in red meat. TMA is converted to toxic trimethylamine N-oxide (TMAO) in the liver via flavin monooxygense 3 (FMO3). The objective of this study was to examine if vegan diets impact TMA levels thus supporting cardiovascular health. We hypothesize that a vegan diet will foster bacterial diversity that favors decreased TMA/TMAO levels. Zebrafish were initially placed on antibiotics to clear their microbiome, following treatment, fish were fed a control, high fat (HF), or vegan diet for 3 weeks. Fish were sacrificed and intestinal, liver and heart tissue were harvested for analysis. Surprisingly, we observed the most significant increase in bacterial abundance in the HF diets relative to the vegan and control diets (n= 5-6, p< 0.05). Interestingly, when separated by sex, the highest change in bacterial abundance was seen in female fish on a HF diet. We next examined mRNA levels of FMO3. We saw the greatest increase in FMO3 levels in female fish on a HF diet, which corresponds to higher bacterial abundance (n= 5-6, p< 0.05). FMO3 levels were also increased for fish on a HF diet relative to the control diet with no significant differences between male and female fish. These results indicate that vegan diets may alter male and female bacterial composition differently and the impacts of these differences on CV health remain unknown.

Funding thus far has come from Elon University.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Thermal and Cardiovascular Responses During a Very Hot and Dry Heatwave Simulation in Young and Older Adults
Authors: Foster Josh , McKenna Zachary , Sarma Satyam , Macnamara James , Belval Luke , Watso Joseph , Atkins Whitley , Orth Bonnie , Johnson Elias , Benning Mayah , Jarrard Caitlin , Crandall Craig
Published: May 2023

Heatwaves cause disproportionately high mortality rates in those aged ≥ 65 years. While age differences in the cardiovascular responses to heat stress have been investigated, previous studies used a water-perfused suit to elicit heat stress. Therefore, how aging affects the cardiovascular responses to prolonged environmental heat stress is not fully understood. Purpose: We tested the hypothesis that 3 hours of exposure to a very hot and dry heat wave condition would increase core temperature and left ventricular systolic contractility (s’) to a greater extent in older, compared with younger adults. Methods: Healthy young (n = 13, 6F/7M, 29±4 years, 1.82±0.13 m-2) and older (n = 19, 10F/9M, 70±4 years, 1.85±0.18 m-2) adults were exposed to 47°C, 15% humidity) for 3-hours, interspersed with seven 5-minute bouts of physical activity at 3 METS to replicate heat generation associated with activities of daily living. Core temperature, brachial blood pressure and heart rate were monitored continuously during heating. Echocardiograms were obtained at baseline (in a thermoneutral environment) and at three hours into heat stress (i.e., post-heat wave) to assess s’. Drinking water was provided throughout the protocol to minimize dehydration. The magnitude of the change in each variable from baseline to post-heatwave between age groups was compared using independent samples t-tests. The association between the change in core temperature and the change in s’ was assessed with linear regression. Results: From baseline to 3-hour heatwave exposure, there was a greater increase in core temperature (Δ1.36±0.28 vs Δ0.74±0.28 °C, p < 0.0001) and s’ (Δ3.3±2.2 vs Δ1.6±1.8 cm/s, p = 0.011) in older, compared with younger subjects, respectively. However, the magnitude of the change in core temperature was not associated with the increase in s’ in older of young subjects (R2 = 0.065 and 0.120, respectively). The older subjects showed a greater decrease in mean arterial pressure compared with younger subjects (-14±10 vs -4±7 mmHg, p = 0.004). Heart rate increased similarly in older and young subjects (27±13 vs 27±12 b/min, p = 0.412). Conclusions: Our findings suggest that an index of left ventricular systolic contractility (s’) increases to a greater extent in older, compared with younger subjects. The change in s’ was not associated with the change in core temperature in either age group.

Supported by NIH R01AG069005 (CGC), F32HL154559 & K01HL160772 (JCW), and F32HL154565 (LNB).

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.
Insulin-regulated aminopeptidase (IRAP) is required for appropriate dilution of urine after an acute water load
Authors: Zuchowski Yvonne , Carty Joshua , Trapani Jonathan , Bock Fabian , Terker Andrew , Zhang Mingzhi , Harris Raymond , Arroyo Juan Pablo
Published: May 2023

Study Objective: Understand the response to acute water load in mice lacking the insulin-regulated aminopeptidase (IRAP). Hypothesis: IRAP degrades vasopressin in vivo, therefore, mice lacking IRAP would have impaired ability to dilute urine and to excrete water. Methods: Age matched 8–10-week-old IRAP WT and KO male mice were used for all experiments. Immunofluorescence and immunoblotting were performed on kidneys at baseline and after 1-hr acute water load (2ml sterile water/IP). Urine/serum electrolytes and urine osmolality were measured before and after water load. Urine was collected from IRAP WT and KO mice before and after 1-hr administration of OPC 31260 (10mg/kg/IP) and furosemide (2.5mg/ml/IP) for urine osmolality and electrolyte measurements. Results: IRAP is expressed in the glomerulus, thick ascending loop of Henle, distal tubule, connecting and collecting ducts. At baseline, IRAP WT and KO mice have similar systolic blood pressure (122 ± 6.6 vs 128 ± 1.9 mmHg), glomerular filtration rate (251 ± 20 vs 254 ± 16 uL/min), and serum Na+ levels (142 ± 1.9 vs 143 ± 2.6 mmol/L), but KO mice have reduced proteinuria (3.3 ± 0.57 vs 4.5 ± 1.6 mg/mg). At baseline, IRAP KO have elevated serum copeptin levels (111 ± 43 vs 53 ± 31 pg/mL) and urine osmolality compared to respective IRAP WT (2506 ± 310 vs 1007 ± 212 mOsm/L). Urine osmolality decreased in IRAP KO after administration of vasopressin type 2 receptor antagonist, OPC 31260 (473 ± 341 vs 2479 ± 215 mOsm/L) and loop diuretic, furosemide (517 ± 96 vs 2750 ± 414 mOsm/L). After an acute water load, IRAP KO have lower serum Na+ levels (127 ± 3.8 vs 134 ±3.1 mmol/L) and increased urine osmolality compared to IRAP WT (2741 ± 400 vs 577 ± 274 mOsm/L). Additionally, after an acute water load, IRAP KO mice also have higher protein abundance of the Na+/K+/2Cl- (NKCC2) co-transporter (0.36 ± 0.04 vs 0.20 ± 0.03 AU) and phosphorylation of water channel, AQP2 (0.032 ± 0.005 vs 0.025 ± 0.003 AU). Conclusions: IRAP is required to dilute urine and to increase water excretion in response to an acute water load due to persistent activation of NKCC2 and AQP2.

Funding Sources: Harold Amos Medical Faculty Development Award - Robert Wood Johnson Foundation; Vanderbilt Center for Kidney Disease

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 impacts of transportation on rodent research models
Authors: Abbaspour Raman
Published: May 2023

There are well established links between excessive commuting and negative health consequences for humans. From a physiological perspective, commuting increases BMI and blood pressure while decreasing cardiorespiratory fitness and physical activity. From a psychological perspective, commuting increases sleep disorders and psychological stress. These negative consequences are also observed in animals. In addition to the adverse effects on the wellbeing of research animals, the impact of transportation threatens the scientific accuracy of our models. The intensive development, use and sharing of diverse rodent models in scientific studies, requires ongoing and at times global shipment of many animals. This transportation heavily impacts rodent physiology, including cardiovascular, endocrine, immune, and digestive systems. These all lead to changes in their neurophysiology and ultimately, behavior. If not accounted for, these practices will introduce confounding variables with the potential to conflate most studies. This review summarizes the research from the last 20 years in this area. Specifically, the effects of transportation on rodent physiology and behavior are reviewed. Through meta-analysis, these changes are quantified and analysed. Lastly, some recommendations for optimizing rodent transportation are discussed, to reduce the adverse effects of shipping and provide a means for mitigating this key but underappreciated aspect of contemporary animal research.

Canada Research Chair Program and NSERC

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Adhering to occupational heat stress recommendations attenuates kidney injury risk
Authors: Hess Hayden , Baker Tyler , Tarr Macie , Johnson Blair , Hostler David , Schlader Zachary
Published: May 2023

Occupational heat stress increases kidney injury (KI) risk due to the development of hyperthermia and dehydration. Workplace recommendations aim to maintain core temperature below 38.0°C and prevent dehydration (<2% body mass loss) in unacclimated workers. We hypothesized that KI risk would be attenuated when adhering to occupation heat stress recommendations compared to a work-matched positive control trial that was non-compliant with the recommendations. Twelve healthy adults (6 women) completed 4 h exposures to wet bulb globe temperatures of 30±2°C (Compliant [C]) and 36±0°C (Non-compliant [NC]). Subjects walked on a treadmill evoking a rate of metabolic heat production of 462±96 W. Consistent with the recommendations, work-rest ratios were prescribed as 15 min of walking and 45 min of rest per hour and subjects were provided 237 mL of sport drink every 15 min and drank ad libitum. Core temperature is presented as an average over the 4 h exposure. Percent change in body mass from pre- and postexposure provided an index of body water loss. Urine samples were collected preexposure, and immediately and 1 h postexposure. KI biomarkers of urinary insulin-like growth factor-binding protein 7 [IGFBP7] and tissue inhibitor of metalloproteinase 2 [TIMP-2] were measured and normalized to urine flow rate. The peak change in the product of IGFBP7 and TIMP-2 (Δ[IGFBP7xTIMP-2]) provided an overall index of KI risk. Data are presented as mean±SD. Average core temperature was lower in the C (37.3±0.3°C) compared to the NC (38.2±0.2°C; p<0.01) trial. Percent changes in body mass did not differ between the C (-0.3±0.6%) and NC (-0.7±1.0%; p=0.19) trials. UFR decreased from pre (C: 5.7±3.1 mL/min; NC: 5.2±3.1 mL/min) to postexposure (C: 2.2±1.8 mL/min; NC: 0.8±0.5 mL/min; p≤0.02) but was not different between trials (p=0.07) and returned to preexposure values 1 h postexposure (p≥0.21). IGFBP7 did not change over time (p=0.27) and was not different between trials (p=0.56). In contrast, TIMP-2 increased from preexposure (C: 0.2±0.2 ng/min; NC: 0.4±0.4 ng/min) to postexposure (C:7.1±17.7 ng/min; NC: 49.3±103.3 ng/min) in both trials (p≤0.01) and was higher in the NC trial both postexposure (p=0.02) and 1 h postexposure (C: 0.2±0.2 ng/min; NC 14.0±44.3 ng/min; p<0.01). Finally, peak Δ[IGFBP7xTIMP-2] was higher in the NC trial (+16.1±39.7 [ng/mL2]/1000) compared to the C trial (+0.8±1.5 [ng/mL2]/1000; p=0.02). Simulated occupational heat stress elevates KI risk, likely due to distal tubule injury as evident by increases in urinary TIMP-2. Nonetheless, violating the recommendations augmented KI risk when work duration was matched.

RCT: NCT04767347. Supported By: R01OH011528

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.
Micro-RNA-532-3p: a potential target in CKD-HFpEF pathophysiology
Authors: Chade Alejandro , Eirin Alfonso
Published: May 2023

Background: Chronic kidney disease (CKD), an independent risk factor for heart failure with preserved ejection fraction (HFpEF), is present in over 50% of CKD patients and accounts for over 50% of hospital admissions for HF. We showed in a novel swine model of CKD-HFpEF that cardiac abnormalities associate with upregulation of pro-inflammatory nuclear factor kappa B (NF-kB). NF-κB activation is controlled by its natural inhibitor IkBα, a protein encoded by the NFKBIA gene that prevents its nuclear translocation, but the exact mechanisms remain unknown. We hypothesize that micro-RNAs (miRNAs), small noncoding RNAs that regulate gene expression, downregulate cardiac NFKBIA and activates NF-κB contributing to cardiomyocyte injury in CKD-HFpEF. Methods: Unbiased cardiac miRNA-sequencing was performed in normal and CKD-HFpEF pigs (n=4/group, 2 males/2 females). Differentially expressed (fold change ≥2 and false discovery rate (FDR)≤0.05) miRNAs capable of targeting NFKBIA were identified using miRWalk 3.0 and Target Scan 8.0, further validated by qPCR. To study the impact of CKD-HFpEF on cardiac tissue, cardiomyocites (CM) were exposed for 48 hours to plasma from normal and CKD-HFpEF pigs (n=3 each) and cardiac injury (LDH release) evaluated, and selected miRNAs modulated (mimic, antagomiR). Results: All CKD-HFpEF pigs showed a significant reduction in renal hemodynamics and function compared to controls accompannied by left ventricular hypertrophy (LVH), abnormal diastolic relaxation and LV strain, and increased circulating ANP and BNP levels, underscoring successful developing of CKD-HFpEF.Unbiased miRNA-seq identified 402 miRNAs targeting NFKBIA, of which 13 were broadly conserved among vertebrates and only 4 expressed in pig’s cardiac tissue. Among them, only miR-532-3p was upregulated in myocardium of CKD-HFpEF pigs.Expression of miR-532-3p was also higher in CM exposed to CKD-LVDD plasma or miR-532-3p mimic, associated with down-regulation of NFKBIA and LDH release. Treatment with anti-miR-532-3p decreased miR-532-3p, increased NFKBIA expression, and reduced CM injury. Conclusions: These observations support a role of miR-532-3p in cardiac NF-kB activation in CKD-HFpEF. In turn, these proof-of-concept studies may assist to identify novel therapeutic targets and develop new interventions to protect the heart in CKD.

NIH HL095638 (ARC), DK129240 (AE)

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.
Metacognitive training did not increase retention of content in upper-division Anatomy and Physiology course
Authors: Schaefer Jennifer , Odegard Jack
Published: May 2023

Metacognitive training was embedded into an upper-division Human Anatomy and Physiology course to examine whether training improved student metacognition and retention of course content. Training included explicit instruction on the definition and value of metacognition, practice in course-specific metacognitive strategies, and assignments in which students reflected on their metacognitive strategies and how their metacognitive strategies could be altered to improve learning and exam grades. Previous work indicated that metacognitive training improved self-reported metacognitive practices and protected against declines in student self-efficacy, but did not improve exam scores. Therefore, we wondered whether the benefit of metacognitive improvement was in content retention rather than improved exam scores. This study hypothesized that metacognitive training, and the subsequent gains in self-reported metacognitive practices, would improve student retention of course content one month after the end of the course. Results indicate that students who received metacognitive training improved self-reported metacognitive practices while student who did not receive training did not improve metacognitive practices. However, metacognitive training did not alter the level of course content retained one month after the end of the course.

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.
Acute effects of fentanyl on carotid body sensory activity
Authors: Garcia Ethan , Srinivasan Dhivya , Chang Andy
Published: May 2023

Opioid drugs have long served as important agents for pain management in the clinic, but misuse of opioids, especially of illicit ultra-potent synthetic opioids like fentanyl, is driving the growing opioid epidemic. Like the natural opioid morphine, fentanyl targets μ-opioid receptor signaling in the central nervous system. However, the pharmacology of fentanyl on the opioid receptors differs from morphine, and clinical symptoms of fentanyl overdose like opioid-induced respiratory depression (OIRD) are more severe and less well-managed by reversal agents like naloxone. Hypoventilation due to OIRD stimulate peripheral chemoreceptors like the carotid body (CB). Previous reports suggest that morphine has minor effects on CB sensory output or the hypoxic ventilatory response mediated by the CB in animal models. Denervation of the CB significantly attenuates the hypoxic ventilatory response of unaesthetized rats after morphine treatment, suggesting that CB sensory activity persists in the presence of morphine to defend against OIRD. However, the effect of fentanyl on CB sensory responses has been little explored. Our goal was to determine how fentanyl regulates CB activity at the level of glomus cells, neuroendocrine sensory cells in the CB that signal to afferent nerves that project to the brainstem to increase ventilation. Sensory stimuli like hypoxia induce calcium transients in glomus cells across all species studied, including human. By two-photon imaging, we performed calcium imaging of mouse glomus cells expressing the genetically encoded calcium indicator GCaMP3 in intact CBs. Whereas morphine suppresses the activity of neurons in the central nervous system, application of fentanyl at levels sufficient to induce OIRD in mice acutely increased calcium transients in CB glomus cells. This increase in intracellular calcium was suppressed by naloxone, indicating that the stimulatory effect of fentanyl was mediated through opioid receptor signaling. In addition, we tested if glomus cells could respond to sensory stimuli in the presence of fentanyl. We found that the combination of fentanyl and hypoxia (PO2~25 mmHg) increased calcium responses over either fentanyl or hypoxia alone. These results suggest that CB stimulation through sensory pathways could potentially be targeted to increase ventilation in OIRD. Experimental groups contained 22-73 cells from least two preparations from different animals, and p<0.05 was set as a significant difference using appropriate statistical test.

This work is funded by a UCSF Innovation Ventures Catalyst Grant and NIH Grant R41DA056270. AJC is a co-founder of Olfa Thera, Inc.

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.
Expansion microscopy and biorthogonal labeling with non-canonical amino acids enables cluster analysis of Na, K-ATPase in the plasma membrane
Authors: Edwards Steven , Bauer Sebastian , Graef Philipp , Meineke Birthe , Elsässer Simon , Brismar Hjalmar
Published: May 2023

Recent developments in expansion microscopy and techniques for site-specific fluorescent labeling of proteins opens new possibilities to study nano-scale protein distributions. We have studied the spatial distribution of Na, K-ATPase alpha and beta subunits in the plasma membrane of epithelial cells. For this we developed sample preparation protocols based on genetic code expansion, click chemistry and expansion microscopy. We transiently transfected HEK 293T cells with constructs containing the coding sequence for the Na, K-ATPase subunits (alpha1 and beta1) carrying a premature amber or ochre stop codon. Two bioorthogonal tRNA and tRNA synthetase pairs were also transfected for stop codon suppression and site-specific insertion of two unnatural amino acids, ProK and TCO*K. The unnatural amino acids were then labelled with small organic dyes using CuAAC and SPIEDAC click reactions.The dyes AF488 picolyl azide and Abberior STAR 635 tetrazine were used to label the two subunits on living cells. Expansion microscopy was performed using a modified MAP protocol, reaching an isotropic expansion of approximately 4.5-fold. Confocal airyscan microscopy of the expanded cells with <50nm resolution revealed nanoscale variations in Na, K-ATPase density and enabled detailed analysis of the proteins distribution. We propose that the spatial distribution of Na, K-ATPase in the plasma membrane has a regulatory function for the local ion pumping efficiency in the cell.

VR 2020-05347, VR 2019-00217 (Swedish Research Council)

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 T-type channels in the differential response to oxytocin of virgin and proven breeder rats uteri
Authors: Porta Maura , Boyman Elisabeth , Sondgeroth Korie
Published: May 2023

Introduction: It is commonly known that an increase in parity is associated with faster labor times, increased risk of hemorrhage, and greater chance of spontaneous delivery (1). The mechanisms of these differences have not yet been fully elucidated. Earlier research conducted in the lab demonstrated that pregnancy alters the response of uterine muscles to oxytocin. Hypothesis: We hypothesized that the intracellular calcium handling machinery, particularly T-type calcium channels, contributes to the differential response to oxytocin in the myometrium from virgin (V) and proven breeder (PB) rats. Methods: Virgin (V) and proven breeder (PB) NP female 18-week-old rats were staged and euthanized at proestrus. One uterine horn was dissected in strips suspended in a tissue bath containing Krebs solution (in mM, NaCl 117, KCl 4.7, NaHCO3 25, MgCl2 1.2, KH2PO4 1.2, CaCl2 2.5, glucose 11, pH= 7.4) at 37°C and bubbled with 95% O2 and 5% CO2. Dose response curves to oxytocin (10E-10 to 10E-5 M) were recorded in the presence of the T-type calcium channels inhibitor Mibefradil. Contractility was evaluated as the area under the curve of recorded contractions. The other uterine horn was flash frozen in liquid NO2 and later used for qRT-PCR experiments. T-tests and ANOVA two ways were used for statistical analysis. Results: Mibefradil significantly reduced the spontaneous contractility of the sample and the response to oxytocin (P<0.001). The maximal contractility in the two groups was similar, whereas in the experiments without the drug PB max contractility was higher. However, the range of activation (Max-Min) was higher for PB samples, as previously observed in the absence of the drug. RT-PCR revealed a two-fold increase in T-type channel receptors on the PB uterus compared to the V. Conclusions: Although T-type channels are slightly more expressed in PB than in V uterine tissue, their impact on the differential response to Oxytocin mechanism is limited. Thus, L-type Calcium channels seem to play a more important role in this mechanism.

This study was supported by a Kenneth Suarez Fellowship to EB and an MWU intramural fund to MP

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 pedunculopontine tegmental nucleus is not important for breathing impairments observed in a Parkinson's disease model
Authors: Miranda Nicole , Oliveira Luiz , Aquino Yasmin , Moreira Thiago , Takura Ana Carolina
Published: May 2023

Parkinson's disease (PD) is a motor disorder resulting from degeneration of dopaminergic neurons of substantia nigra pars compacta (SNpc), with classical and non-classical symptoms such as respiratory instability. An important region for breathing control, the Pedunculopontine Tegmental Nucleus (PPTg), is composed of cholinergic, glutamatergic, and GABAergic neurons. Our main hypothesis is that degenerated PPTg neurons contribute to the blunted respiratory activity in a PD model. Adult mice (males and females) (CEUA: 6641200919) that express the fluorescent green protein in cholinergic, glutamatergic or GABAergic cells were used (Chat-cre Ai6, Vglut2-cre Ai6 and Vgat-cre Ai6) and received bilateral intrastriatal injections of vehicle or 6-hydroxydopamine (6-OHDA, 10 μg/μl). Ten days later, the animals were exposed to hypercapnia (7% CO2) or hypoxia (8% O2) to activate PPTg neurons. Vglut2-cre Ai6 animals also received retrograde tracer injections (cholera toxin b) into the retrotrapezoid nucleus (RTN) or preBötzinger Complex (preBötC) and anterograde tracer injections (AAV-mCherry) into the SNpc. In 6-OHDA-injected mice, there is 79% of reduction in the number of dopaminergic neurons in SNpc (95.09 ± 4.77 vs. vehicle: 456.6 ± 6 neurons) without changing the number of glutamatergic, GABAergic and cholinergic neurons in the PPTg. Hypercapnia activated fewer Vglut2 neurons in6-OHDA animals (8.6 ± 2.7 vs. vehicle 19.5 ± 2.9 neurons), and hypoxia did not activate PPTg neurons. PPTg neurons do not input RTN or preBötC regions but receive projections from SNpc. Although our results did not show a reduction in the number of glutamatergic neurons in PPTg, we observed a reduction in the number of neurons activated by hypercapnia in the PD animal model, suggesting that PPTg may participate in the hypercapnia ventilatory response.

Funding: FAPESP, CAPES and CNPq

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.
Palmitic acid induces Oxidative Stress, Senescence and Downregulates Glutamate Transporter Expression in Human Brainstem Astrocytes
Authors: Sivasubramanian Mahesh Kumar , Monteiro Raisa , Balasubramanian Priya , Subramanian Madhan
Published: May 2023

Glial cells have emerged as critical players in sympathoexcitation and neurogenic hypertension in recent years. Glutamate reuptake transporters display a high vulnerability to oxidative stress resulting in reduced uptake function. We have previously shown that obesity increases superoxide production and 3-nitro-tyrosine levels in the RVLM, suggesting that obesity-induced reduction in EAAT2 expression and activity might be mediated through oxidative stress. Our preliminary studies in human primary brainstem astrocytes (HBAs) also suggest that oxidative stress negatively impacts EAAT2 expression. However, what obesity-related factors induce oxidative stress in the brainstem of obese animals is not clear. In this study, we will test the role of palmitic acid on oxidative stress and astrocytic function in the brainstem. Cultured human brainstem astrocytes were treated with palmitic acid at the dose rate of 25μM for 24 hours. After the treatment period, the cells were collected and processed for real-time PCR analysis. Data was analyzed by unpaired student's t-test and a p-value less than 0.05 was considered statistically significant. Major findings from this study includes a) Palmitic acid mimicked obesity and increased lipid accumulation in brainstem astrocytes marked by significant increase in the expression lipid-droplet associated proteins, perilipin (PLIN) 1 and 2 b) We also found that the oxidative stress markers, NQO1, SOD2, and catalase were significantly higher in treatment group indicating that palmitic acid induced oxidative stress in brainstem astrocytes. c) Gene expression analysis of senescent markers revealed p21 and p53 were significantly upregulated in the treatment group. In addition, Lamin B1, a component of the nuclear envelope was significantly downregulated in the treatment group consistent with the senescence. d) Then we also observed increased gene expression levels of the senescence-associated secretory phenotype (SASP) factors, IL1α, TNFα, IL6, MCP1, and CXCL10, indicative of oxidative stress-induced senescence in brainstem astrocytes treated with palmitic acid. e) More importantly, the levels of glutamate reuptake transporters, EAAT1 and EAAT2 were significantly downregulated in the senescent brainstem astrocytes. Taken together all these results suggest that the palmitic acid induces oxidative stress, senescence and inflammation in the human brainstem astrocytes that could mediate sympathoexcitation through enhanced glutamate neurotransmission in the brainstem in obesity.

National Heart, Blood and Lung Institute grant R15HL148844; American Heart Association Institutional Research Enhancement Award - 959725

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 relationship between VO2 max and MSNA in healthy young adults
Authors: Baron John , Loggie Nicole , Corkery Adam , Howery Anna , Miller Kathleen , Eldridge Marlowe , Barnes Jill
Published: May 2023

BACKGROUND: Muscle sympathetic nerve activity (MSNA) has been shown to be a predictor of cardiovascular diseases. There are currently disputed findings regarding the effects of exercise training on MSNA at rest. Therefore, this study sought to compare MSNA in young exercise trained and sedentary adults. The purpose of this analysis was to examine associations between MSNA at baseline with VO2max in order to determine if VO2max can be a predictor of MSNA. METHODS: Forty-two young adults were evaluated including 11 resistance trained (RE: age = 24 ± 4 years; BMI = 24 ± 2 kg/m2), 18 aerobically trained (AE: age = 27 ± 5 years; BMI = 24 ± 2 kg/m2), and 13 sedentary controls (CON: age = 28 ± 5 years; BMI = 25 ± 2 kg/m2). Participants underwent a maximal exercise test to exhaustion on a cycle ergometer to measure VO2max. During a separate visit, mean arterial pressure (MAP), heart rate (HR) and MSNA were measured at rest for five minutes. MSNA was assessed using burst frequency, burst incidence, and total activity. One-way ANOVA was performed in order to assess between-group differences in MSNA. Simple linear regression was performed in order to determine the impact of VO2max on MSNA and the relationship between MAP and VO2max. RESULTS: There were significant differences in VO2max across all three groups (RE: 41.4 ± 4.6 ml/kg/min; AE: 46.2 ± 4 ml/kg/min; CON: 35.3 ± 6.7 ml/kg/min; p < 0.01) and between groups (RE vs. AE p < 0.01; RE vs. CON p < 0.02; AE vs. CON p < 0.01). There were no differences in MSNA burst frequency (RE: 15 ± 8 bursts/min; AE: 17 ± 7 bursts/min; CON: 18 ± 5 bursts/min; p = 0.57), MSNA burst incidence (RE: 36 ± 13 bursts/100 cardiac cycles; AE: 34 ± 15 bursts/cardiac cycles; CON: 30 ± 7 bursts/100 cardiac cycles; p = 0.27), and total MSNA (RE: 881 ± 684 B/min; AE: 1361 ± 1092 B/min; CON: 1031 ± 379 B/min; p = 0.29) across the three groups. There were no relationships found between VO2max and MSNA burst frequency (r = 0.23; p = 0.15), VO2max and MSNA incidence (r = 0.06; p = 0.71), or VO2max and total MSNA (r = 0.03; p = 0.89). CONCLUSION: In conclusion, these results demonstrate a disassociation between MSNA and VO2max at rest in young adults. Since this analysis was limited to resting values, future studies could examine the relationship between VO2max and MSNA as a result of an exercise training intervention.

Funding: NIH HL118154, Virginia Horne Henry

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.
Regulation of hyaluronic acid synthesis and breakdown can prevent significant damage of the lung epithelium in response to SARS-CoV-2 infection
Authors: Harriott Noa , Calvert Ben , Quiroz Erik , Ryan Amy
Published: May 2023

COVID-19 remains an ongoing global pandemic causing significant respiratory distress and endothelial dysfunction in individuals susceptible to severe disease. Increased production of hyaluronic acid has been observed in patients with severe COVID-19, however its significance in COVID-19 pathogenesis is currently unknown. Hymecromone is a hyaluronic acid synthase inhibitor FDA approved for use in humans as a choleretic. We hypothesized that excessive production of hyaluronic acid by the airway epithelium, in response to SARS-CoV-2 infection, may increase hyaluronan fragments that augment epithelial dysfunction in COVID-19. We therefore evaluated a hyaluronic acid synthase inhibitor, hymecromone, for its potential to regulate the infection of respiratory epithelia by SARS-CoV-2. Using air-liquid interface models we evaluated the impact of SARS-CoV-2 infection on differentiated primary human airway epithelium in the BSL3 facility. At 100μg/ml hymecromone significantly inhibited the cytopathic effects of SARS-CoV-2 on airway epithelium (p<0.001). After 24 hours, SARS-CoV-2 virus accumulated in the basolateral compartment after apical infection of the airway cultures. Hymecromone also significantly inhibited this basolateral accumulation of viral particles versus untreated controls (p<0.05). Additionally, hymecromone alters the cytokine response to SARS-CoV-2 infection, dose-dependently decreasing apical secretion of cytokines including IL-17A/B/D, IL-21 and IL-5, and dose-dependently increasing the basolateral secretion of IL-17A/D and IL-1RA. All experiments were performed on three independent donor cells with three experimental repeats per condition. In conclusion, our data highlight the importance of the regulation of hyaluronic acid production in the response of the airway epithelium to SARS-CoV-2 infection and indicate hymecromone as a potential therapeutic option.

Funding for this study was provided by the Rainwater 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.
The trepidatious return to in-person instruction during the COVID-19 pandemic: valuable lessons applied from online teaching using Lt in the face-to-face classroom
Authors: Ford Bridget
Published: May 2023

The speed at which educators have embraced new technologies during the COVID-19 pandemic has been remarkable. This pivot to virtual instruction has been particularly difficult in courses where hands-on experiences are the norm, such as in anatomy and physiology laboratory courses. Now with the transition back to mostly in-person instruction, the anatomy and physiology lab environment has faced a new set of challenges where the want to return to a strictly hands-on experience is being met with the need to still maintain flexibility and accessibility for students placed in quarantine. The anatomy and physiology lab curriculum at the University of the Incarnate Word (UIW) has adapted to this varied set of needs by adopting the use of the web-based laboratory software platform, Lt. Students surveyed during strictly virtual semesters reported a high level of satisfaction with the Lt lab software. Ratings regarding ease of use, support of learning, and overall ratings increased each semester with the highest ratings occurring during the most recent semesters where instruction was mostly in-person and hands-on (Fall 2021 – Fall 2022). This helps to support the widely held belief that students perform best, and that instruction is more effective with face-to-face laboratory courses. With our continued use of Lt, we have found an effective combination of virtual and in-person instruction that best fits our course outcomes while still supporting the flexibility and accessibility our students require.

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.
Cardiorespiratory depression in mice receiving urethane anesthesia
Authors: Flores Laura , Vasileva Anastasiia , Vasilyev Mikhail , Tomasson Michael , DeRuisseau Lara , Bates Melissa
Published: May 2023

Urethane is used in rats and dogs and is recognized to minimally suppress cardiorespiratory function, but little is known about its impact in mouse models. The overall purpose of this study was to comprehensively compare cardiorespiratory function in mice anesthetized with urethane, compared to conscious state. 16-week old C57BL6/J mice (n=30,15 males, 15 females), underwent measurements while conscious and urethane-anesthetized. Hemodynamic parameters including heart rate variability (HRV), blood pressure (BP), heart rate (HR), and oxygen saturation (SpO2) were acquired using non-invasive (CODA and MouseOx) and invasive (Cardiac catheterization, Millar PVR-1030) techniques. All experiments were repeated with supplemental oxygen. Urethane decreased HRV and SpO2. Oxygen supplementation restored HRV and SpO2. We found no significant difference between invasive and non-invasive measurements of HRV, HR, BP, and SpO2. Urethane depressed BP in a sex-dependent manner. In this first report of the HRV response to urethane anesthesia in mice we found an anesthesia-induced decline in various cardiovascular parameters that is likely the result of urethane-induced hypoxemia. Changes characterizing the autonomic responsiveness to urethane stimuli in mice are described and should be considered when choosing the appropriate anesthetic agent.

NIH1R21HD099573 and 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.
The “form” and “function” of undergraduate anatomy & physiology curricular structure
Authors: Johnson Staci , Gallagher Eliza
Published: May 2023

The life science sub-disciplines of anatomy and physiology are the study of the form and function of a living organism. Our project describes the “form” (curricular structure) and “function” (student experience and learning) in undergraduate anatomy & physiology courses. Prior literature describes student learning approaches within separated or integrated curricula in medical education. However, little information is available about the impact of these curricular structures in undergraduate anatomy and/or physiology courses. This study analyzed the processes used by students in two different undergraduate anatomy & physiology course structures through a comparative case study methodology. Participants were enrolled in either a 2-semester sequence of anatomy then physiology (A-->P, Case 1) or an integrated 2-semester sequence (A&P1-->A&P2, Case 2). Eleven students were interviewed three times and provided written responses to open-ended prompts throughout the courses. These qualitative data were analyzed with four cycles of coding. First, block coding categorized data based on the theoretical frameworks of Biggs, Fyrenius et al., and Pandey & Zimitat. Next, all passages identified in block coding were assigned process codes through an open coding procedure. In the transition phase, code mapping was completed to identify emerging themes. Finally, focus and axial codes were applied, and the cases were compared. While there were differences identified between the cases, these were not specifically linked to curricular structure as we normally define it. Rather, differences were due to instructional design and instructor choices, particularly the presence of formative assessment within the courses. Our findings indicate that the “function” of structure based on course topics or content is a less important detail, while instructional and assessment choices provide the “form” of a course from the student’s perspective. If “form follows function” in this context, instructors in anatomy and physiology courses should recognize the impact of their assessment practices and instructional choices on student affect and subsequent learning within the course.

This project was not supported by any funding sources.

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.