bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel regulation of kidney function by gastrointestinal hormones
Authors: Peresztegi Lena , Peti-Peterdi Anna , Becerra Calderon Alejandra , Izuhara Audrey , Deepak Sachin , Gyarmati Georgina , Peti-Peterdi Janos
Published: May 2024

The control of whole-body energy metabolism involves intricate crosstalk between multiple organ systems including the gut and the brain that play well-recognized roles in this process. However, the important contributions and mechanisms by other organs are poorly understood. Errors in metabolic regulation can lead to human metabolic diseases including diabetes and obesity that affect 75% of the population and can lead to significant comorbidities. Improving our mechanistic understanding of multi-organ metabolic crosstalk in health and disease is essential for developing highly effcient and new therapeutic approaches. Macula densa (MD) cells in the kidney are chief regulators of renal blood flow and tissue remodeling. We hypothesized that the kidney is a major player in body metabolism via a new mechanism of gut-kidney crosstalk that involves the gut hormones gastrin and cholecystokinine (CCK) activating intrarenal, MD-specific mechanisms to increase blood flow and filtration, progenitor cells and tissue growth factors. High-resolution MD bulk and single-cell transcriptome analysis was performed from freshly isolated, enriched MD cells using MD-GFP mouse kidneys. Single cell MD Ca2+ signaling was analyzed in vivo using intravital multiphoton microscopy (MPM) of Sox2-GT mice that express the ratiometric Ca2+ reporter GCaMP6f/tdTomato in all renal cells. The altered expression of MD specific markers in response to gastrin/CCK8 stimuli was studied using western blot and the novel MDgeo immortalized cell line cultured in vitro. RNA sequencing and transcriptome analysis identified the gastrin/CCK receptor Cckbr as one of the highest expressed genes in MD versus control kidney cells. Intravital multiphoton imaging of Sox2-GCaMP6 reporter mouse kidneys revealed robust and entirely MD cell-specific calcium signaling in response to systemic gastrin/CCK injection. Using the novel MDgeo immortalized cell line cultured in vitro, CCK8 treatment led to 3-fold increases in MD cell synthesis of Prostaglandin E2 (PGE2)-generating COX2 and CCN1 that are established mediators of MD-induced glomerular hyperfiltration and tissue remodeling, respectively. Chronic treatment of Ren1d-Confetti mice with Darunavir, an HIV protease inhibitor significantly increased plasma CCK levels, Ren+ mesenchymal progenitor cell number and clonality, renal cell proliferation and tissue hypertrophy. This study uncovered new regulatory mechanisms of systemic metabolism especially the role of MD cells in the kidney. Repurposing the commonly used HIV drug Darunavir for kidney and metabolic diseases may provide therapeutic benefit for millions of patients worldwide.

DK064234, DK123564, DK135290.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Comparative anoxia responses of hatchling and juvenile western painted turtles (Chrysemys picta bellii)
Authors: Membreno Nelson , Warren Daniel
Published: May 2024

The western painted turtle ( Chrysemys picta bellii) is the most anoxia-tolerant tetrapod known, with adults capable of surviving anoxia for more than 170 days at 3°C. However, hatchling painted turtles are known to have an anoxia tolerance of just 40 days at 3°C. It is believed that the reduced mineralization of the hatchling shell likely limits their buffering capacity, but other aspects of their physiology, such as anaerobic metabolic rate and glycogen stores could be limiting as well. We hypothesize that one year-old juveniles, with more mineralized shells, would tolerate anoxia longer than recently hatched turtles. Thirty-five juvenile and hatchling turtles were gradually cold-acclimated from 20°C to 3°C and then placed inside individual cages. Three aquaria (37.85L) each contained eight juvenile and eight hatchling turtles. Eleven control juvenile and hatchling turtles were sampled and flash-frozen for future analysis of tissue glycogen, lactate, and carbonate. The remaining turtles were then submerged in anoxic water and their limb withdrawal reflex tested daily for a loss of response. When half of each developmental group became unresponsive, the remaining responsive turtles were then sampled. The hatchling and juvenile turtles lost their withdrawal reflex after 39.3 ±1.2 days and 42.3 ±2.6 days, respectively, indicating there was no significant difference in anoxia tolerance between the developmental groups. Powdered whole-body turtle samples showed similar total glucose and glycogen levels in juveniles (30.484 μmol/g tissue and 4.875 μmol/g tissue) and hatchlings (27.301 μmol/g tissue μmol/g tissue and 4.718 μmol/g tissue), respectively. Plasma samples showed that juveniles tended to have slightly higher free glucose and lactate (15.160 mmol/L and 6.317 mmol/L) compared to hatchlings (11.118 mmol/L and 5.531 mmol/L), respectively. There was no interaction between anoxia tolerance and life stage. These results suggest that tissue glycogen stores, and not buffering capacity, limits the anoxia tolerance of young turtles.

NSF CAREER grant to DEW.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The Investigation of the Cavernous Nerve
Authors: Villarmán Julio
Published: May 2024

Objectives: To investigate the presence or absence of post-ganglionic cell bodies within erectile tissue. The presence of intramural cell bodies will indicate parasympathetic features. The absence of intramural cell bodies will indicate sympathetic features. Methods:Rabbit monoclonal anti-Neun Alexa488 Immunofluorescence staining on tissue sections from dissections to target neuronal nuclei in the positive controls and erectile tissue sample.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Chronic kidney disease is accompanied by behavioral deficits in rodents
Authors: Di Sole Francesca , Babich Victor , Kornstad Abigail , Tefft Kristin , Duric Vanja
Published: May 2024

Clinical reports indicate a bidirectional relationship between mental illness and chronic systemic disease. Kidney injury and inflammation have been linked to brain dysfunction and alterations in learning and memory, as well as development of anxiety and depression, however, the underlying neurophysiological mechanisms remain elusive. In the current study, we investigated whether a chronic kidney disease (CKD) state is suffcient to produce deficits in rodent stress behaviors using a mild or severe model of CKD. Male rats were exposed to either 21 days of 0.75% adenine diet (AD) (model of mild CKD), or a combination of AD with unilateral nephrectomy (AD/Unx), prior to the start of AD (model of severe CKD). Control rats received sham surgery and remained on normal diet/chow throughout the experimental paradigm. CKD development in the rat models was determined by a significant increase in serum creatinine used as index for kidney function. Behavioral testing results demonstrate that mild CKD model, especially in combination with unilateral nephrectomy (severe CKD model), is accompanied by anhedonia (i.e., decreased sucrose preference) and increased anxiety-like behaviors in the novelty-suppressed feeding, open field and elevated plus maze tests. These findings suggest that impairment of kidney functionality is suffcient to increase behavioral emotionality in rodents consistent with development of depressive-like and anxiogenic phenotype. Ongoing studies are focused on identifying neurophysiological mechanisms linking renal disease with neurological abnormalities. Furthering our understanding of these mechanisms may aid in the development of improved treatments and prevention strategies for management of mental health comorbidities associated with kidney disease.

Des Moines University IOER Research & Grant Award.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Impact of Previous Dietary and Exercise Education on Knowledge of Obesity and its Comorbidities: Case Study on a College Campus
Authors: Ames Olivia , Smith Katelyn , Sharma Naveen
Published: May 2024

Greater than 40% of the adult U.S. population is estimated to be clinically obese based on body mass index (BMI) ≥ 30 kg/m2. Obesity is associated with several debilitating comorbidities that impact both physical and mental health including cardiovascular disease, type 2 diabetes, cancer, and depression. A college community is not immune to obesity, but with a typically younger and more active population the prevalence of obesity is generally lower on campus than the neighboring area. We hypothesized that a formal education of diet and exercise would be strongly associated with reduced obesity, and moreover an increased knowledge of obesity-linked comorbidities. College students were surveyed on their educational background, obesity and associated comorbidity knowledge, as well as anthropometric information including height and weight. Correlations were analyzed to determine links between education, obesity knowledge, and BMI. We received completed surveys from 158 students with an average age of 20.5 ± 3.0 years and BMI of 24.5 ± 5.1 kg/m2. Students with formalized education in diet and exercise were more informed about current nutritional and physical activity guidelines than those students who had not received similar education. Despite this disparity, both groups of students were similarly knowledgeable about obesity and its comorbidities. Additionally, there was no difference in the self-reported BMIs between these two groups of students. Based on our survey, the prevalence of obesity was 10.8%, much lower than the national average. We conclude that a formal education in diet and exercise did not lead to differences in weight status or obesity knowledge amongst students on this college campus. This suggests that on-campus health promotion initiatives regarding obesity would be equally beneficial to all students regardless of educational background.

Honors Program; Herbert H. & Grace A. College of Health Professions; Offce of Graduate Studies Central Michigan University.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Histone Deacetylase Inhibition Increases Glycerol Uptake in Normal and Hyperglycemic Conditions in Human Corneal Epithelial Cells
Authors: Melnyk Samuel , Choudhary Vivek , Lu Xiaowen , Chen Zhong , Watsky Mitchell , Bollag Wendy
Published: May 2024

Delayed corneal wound healing, such as is seen in diabetes, can lead to visual impairment. Diabetes afflicts over 30 million Americans and leads to multiple comorbidities. Histone deacetylase (HDAC) expression and activity are increased in diabetes in correlation with an upregulation of inflammatory molecules and reactive oxygen species (ROS). HDACs have been previously found to suppress the expression of the glycerol channel aquaporin-3 (AQP3) in epithelial cells of the skin, the epidermal keratinocytes. Global deletion of AQP3 in mice has been found to delay corneal wound healing. We hypothesized that hyperglycemic conditions would decrease AQP3 levels and function while increasing the expression of HDAC(s), ROS scavenger proteins, and inflammatory mediators in human corneal epithelial cells (HCECs). HCECs were incubated for 48-hours in high glucose (25.5 mM) or normal glucose (~5.0 mM osmotically matched by mannitol) conditions. Under hyperglycemic conditions, the mRNA expression of interleukin-1α and -1β was significantly elevated, providing evidence for a pro-inflammatory effect of acute hyperglycemia in HCECs. Under these conditions, there was a significant increase in the mRNA expression of the ROS scavenger genes, superoxide dismutase-1 and -2 and peroxiredoxin-3 and -6, suggesting a compensatory response to an increase in ROS generation. Under acute hyperglycemic conditions, HDAC3 and HDAC8 mRNA expression also tended to increase while HDAC1 and HDAC2 mRNA levels remained unchanged. Although an upregulation of HDAC expression would be predicted to decrease AQP3 expression, AQP3 mRNA and protein expression levels were also unchanged. In addition, acute hyperglycemia (48 hours) did not alter glycerol transport into the HCECs, as measured by their uptake of radiolabeled [14C]-glycerol. However, HDAC inhibition using the broad-spectrum inhibitor SAHA for 24 hours increased [14C]-glycerol uptake under both normoglycemic and hyperglycemic conditions, suggesting that HDAC activity plays a role in AQP3 function. Overall, acute hyperglycemic conditions were pro-inflammatory and led to increased expression of ROS-scavenging genes; hyperglycemia also tended to upregulate HDAC expression, although without affecting AQP3 expression. On the other hand, HDAC inhibition increased glycerol uptake, an indicator of AQP3 function, suggesting an ability of HDAC activity to regulate AQP3 glycerol transport activity.

National Institutes of Health/National Eye Institute award #R01EY030576 (to MW and WBB) VA Merit #BX005055 (to WBB).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
miRNA-221 and -222 increase in exosomes upon insulin stimulation of human vascular smooth muscle cells lacking the insulin-like growth factor 1 receptor
Authors: Bradford Angelle , Woods T. Cooper
Published: May 2024

As a result of increased vascular inflammation, patients with Type 2 diabetes experience a near 4-fold increase in their risk for heart attack and stroke. miR-221 and -222 are two microRNAs that are upregulated in the vasculature of Type 2 diabetic patients. miR-221/222 act by downregulating the cyclin-dependent kinase inhibitor, p27Kip1, in vascular smooth muscle cells (VSMCs) and exosome-mediated proinflammatory effects on endothelial cells and macrophages. Loss of the insulin-like growth factor receptor (IGFR) in VSMCs can unmask the insulin receptor (IR) and increase insulin signaling. We have demonstrated that the loss of IGFR, coupled with physiological insulin stimulation, promotes an increased expression of miR-221/-222 in murine VSMCs. Respectively, miR-221/222 content in VSMC-derived exosomes increases and p27Kip1 mRNA expression decreases in VSMCs. We asked whether the effect of loss of IGFR in human coronary artery smooth muscle cells (HCASMCs) would also lead to an increase in miR-221/-222 content of VSMC-derived exosomes. Transfection with a CRISPR-cas9 plasmid targeting IGFR resulted in a 50% decrease in IGFR mRNA in HCASMCs, when compared to transfection with negative control CRISPR plasmids. Droplet digital PCR was used to measure expression of miR-221 and miR-222 in the exosomes derived from both sets of HCASMCs. There was no change in the miR-221/222 content of exosomes derived from HCASMCs transfected with the negative control CRISPR following stimulation with 1nM insulin (7.27± 4.75 vs. 11.33 ± 1.09 copies of miR-221 and 6.43 ± 0.43 vs. 4.68 ± 0.02 copies of miR-222). In contrast, there was a 2 to 3-fold increase in miR-221/222 content in exosomes that were derived from HCASMCs with IGFR knockdown following stimulation with 1nM insulin (14.96 ± 0.3 vs. 35.66 ± 3.08 copies of miR-221 and 9.12 ± 1.19 vs.15.44 ± 5.36 copies of miR-222). We conclude that loss of IGFR coupled with physiological insulin stimulation increases the miR-221/222 content of exosomes of HCASMCs, recapitulating the effects of IGFR loss seen in murine VSMCs as well as the effects of diabetes on VSMCs. This model system will allow additional studies connecting the loss of IGFR to the cardiovascular complications of diabetes.

Tulane University School of Medicine, Biomedical Sciences Program.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Topographical distribution and morphology of TH-IR and VAChT-IR axons in the antrum, pylorus, and duodenum of rats
Authors: Chen Jin , Bendowski Kohlton T. , Zhang Yuanyuan , Cheng Zixi Jack
Published: May 2024

The autonomic nervous system plays an essential role in controlling gastrointestinal functions including a variety of physiological functions such as the regulation of motility, gut secretion, and vascular flow. Tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT) are commonly used markers for sympathetic and parasympathetic innervation, respectively. However, the regional distribution and morphology of TH-IR and VAChT-IR axons in the submucosa and mucosa are not well documented. In this study, the rat antrum-pylorus-duodenum (APD) were transversely and longitudinally sectioned. A Zeiss M2 imager was used to scan the serial sections of each APD (each section montage consisted of 50–100 all-in-focus maximal projection images). To determine the detailed structures of TH-IR and VAChT-IR axons, we used the confocal microscope to scan the regions of interest. We found that (1) TH-IR axons innervated the muscular, submucosal, and mucosal layers. In the muscular layer, the submucosa and the mucosa, TH-IR varicose axons innervated the muscles and innervated blood vessels. In the villi, TH-IR axons were presented. (2) VAChT-IR axons heavily innervated the muscular, submucosal, and mucosal layers. In the muscular layer, VAChT-IR varicose axons densely innervated the muscles and myenteric neurons were VAChT positive. In the submucosa and mucosa, VAChT-IR axons innervated as well. In the villi, VAChT-IR axons were densely innervated. (3) TH-IR and VAChT-IR axons were found not co-localized in the muscular, submucosal, and mucosal layers. This work provided a comprehensive view of the distribution and morphology of TH-IR and VAChT-IR axons in the APD at single cell/axon/varicosity scale. This data will be used to create a 3D mapping of the TH-IR and VAChT-IR axons innervation of the APD in rats.

This study was supported by NIH HEAL/SPARC U01 NS113867-01 and NIH R15HL137143-01A1.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Effcacy of a chimeric PlGF derived protein for the management of preeclampsia
Authors: Chapman Heather , Moore Kyle , Bidwell Gene , George Eric
Published: May 2024

Preeclampsia (PE) is one of the most common complications of pregnancy, affecting ~5-7% of pregnancies. Hallmarked by new onset hypertension and maternal endothelial dysfunction, PE is believed to be caused by insuffcient blood flow to the placenta. This causes the release of factors into the maternal circulation; notably the soluble VEGF receptor sFlt-1, which antagonizes the effects of VEGF in the endothelium. Placental growth factor (PlGF) is a VEGF family member produced by the placenta that only binds to the Flt-1 receptor and has little inherent angiogenic activity. We hypothesized that administration of a stabilized chimeric PlGF-derived protein (ELP-PlGF) would antagonize sFlt-1 in a rodent model of PE, and help resolve the maternal symptoms. We therefore utilized the reduced uterine perfusion pressure (RUPP) model of placental ischemia. RUPP animals exhibited a significant increase in blood presssure (99 vs 118 mmHg p<005), while RUPP animals treated with ELP-PlGF demonstrated significantly attenuated hypertension (105mmHg, p<0.05). Likewise, RUPP animals treated with ELP-PlGF showed decreased placental sFlt-1 (512 vs 308 pg/mg, p<0.05), and plasma sFlt-1 by western blot (13877 vs 6860 AU, p<0.05). Further, vascular preproendothelin expression from the aorta decreased 60% between RUPP and RUPP treated animals. Taken together, these results suggest that PlGF-based therapeutics could be a viable approach to the management of PE, and this formulation demonstrates significant effcacy in vivo in a relevant animal model.

This work was partially supported by NIH grants P01HL51971, P20GM104357, and R01HL137791.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Cellular Redox Status of Dermal fibroblasts as a Model to Explore Hypoxia Responses Across Diverse Mammals
Authors: Douglas Micaah , Klink Amy C , Montenegro Janessa , Madelaire Carla , Hindle Allyson G
Published: May 2024

Specializations in energy production pathways can define phenotype in mammals, enabling resilience to environmental stressors and survival in extreme habitats. Most mammals rely on oxygen-based mitochondrial respiration to sustain high rates of ATP production necessary for homeothermy; oxidative phosphorylation is fueled by donation of reducing equivalents (NADH, FADH2) to the electron transport chain. As such, relative redox levels within the cell (NAD+/NADH ratio) indicate cell health and metabolic status. In hypoxic conditions, cells can experience reductive stress, evidenced by a buildup of NADH and altered NAD+/NADH ratio. We are using primary dermal fibroblasts isolated from skin biopsies in n=9 species to compare metabolic changes via the ratio between NAD+ and NADH when exposed to 0.5% O2 for 6-h and 24-h. Species were selected to encompass diverse phylogeny as well as to include species that are adapted to low oxygen environments (high altitude gelada baboons, diving humpback whales and Weddell seals). Control species without adaptation to hypoxic environments included human, dromedary camel, little brown bat, honey badger, and rhinoceros. We expect fibroblasts from species adapted to living with variable oxygen availability to have more stability in NAD+/ NADH ratios when exposed to hypoxia in cell culture compared to those from species that are not adapted to low oxygen environments. We quantified NAD+ and NADH following exposure to hypoxia as well as control normoxic samples. Preliminary data with n=3 biological replicates per species show that fibroblasts from the control animals display significant differences in NAD+/NADH ratio between normoxic and hypoxic treatments (Kruskal-Wallis test, p=0.01), however, there are no significant differences in the ratios presented for tolerant animals (Kruskal-Wallis test, p=0.518). This finding supports our hypothesis that animals adapted to low oxygen reduce variability in the NAD+/NADH ratios. Understanding the metabolic patterns when cells are exposed to reduced oxygen levels can provide a framework for estimating a species resilience to environmental variation.

Funded by NSF #2022046, CSUN-OUR Summer Undergraduate Fellowship.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Diet Shifts Alter the Activity and Distribution of Digestive Enzymes in an Herbivorous Fish
Authors: Rafanan Kirsten , Herrera Michelle , German Donovan , Catabay Caitlyn
Published: May 2024

The digestive tract is central to the function of an animal since it assimilates nutrients from the diet. Digestion itself is a chemical process and digestive enzymes are the digestive catalysts. Thus, we measured amylase, maltase, N-acetyl-b-d-glucosaminidase, lipase, trypsin, aminopeptidase, and alkaline phosphatase activities along the digestive tract of the marine herbivorous fish, Cebidichthys violaceus. We did this for wild-caught individuals of this species, and compared those to individuals fed carnivore, omnivore, and herbivore diets in the laboratory for six months. In laboratory fish, the enzymatic activities were generally lower compared to wild-caught fish. In wild caught fish, a strong anterior-to-posterior gradient of amylase activity was observed along the gut and this pattern largely disappeared in the lab-fed fish. N-acetyl-β-D-glucosaminidase (NAGase), which breaks down chitin products, showed an increase in activity in the distal intestines of the lab-fed fish, which is not observed in wild fish. The NAGase activity of the herbivorous fishes correlate with the bacterial species Paroccus sp., which is a known NAGase producer, and one of the dominant microbes in the distal intestines of the lab-fed fish. The role of this enzyme, however, remains unclear since the lab diets did not contain large amounts of chitin. These enzymatic differences tell us how much fish can modify their enzymatic activity to align with their diet. In summary, the findings show that C. violaceous can endure different degrees of protein and carbohydrate levels, within limits. Their digestive system clearly changed in response to more protein in the diet, along with a microbiome that had more potential pathogens. Live algal diets would may be the most suitable for this herbivorous fish based on the totality of gathered data from the lab.

American Physiological Society Fellowship UCI Microbiome Initiative Grant.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mechanosensor channels of the lens and ciliary body: patch clamp studies
Authors: Ek-Vitorin Jose , Rahman Faiz Ur , Shahidullah Mohammad , Delamere Nicholas
Published: May 2024

Epithelia from the lens and the ciliary body possess mechanosensors, including Piezo1 and transient receptor potential (TRP) channels, that may partake in the regulation of lens and aqueous humor volume. Although these mechanosensor channels commonly allow calcium entry, the outcomes of elevated intracellular calcium vary with the type of channel activated. For instance, separate activation of TRPV4 and TRPV1 increases Na-K-ATPase and Na/K/2Cl cotransporter activities, respectively. To further understand the role of mechanosensitivity in lens and ciliary body, we are currently using patch clamp techniques to characterize the response of primary cultured cells to chemical agonists and antagonists, as well as direct mechanical stimulation. Previously, we found that in mouse lens epithelial cells (mLEC), TRPV4 activation by agonist GSK1016790A (GSK) is followed by disappearance of a fast, transient K+-like outward current (Ipeak), decrease of a steady state outward current (Iss), fast depolarization of resting membrane potential (RMP) values from near -50 mV to near 0 mV, increase of Cx43 hemichannel-like events, and increase of overall membrane conductance ( gm) at holding potential (HP) = -50mV. More recently, we found that in mLEC, shear stress (streaming of external solution from a pipette tip over the cell membrane) reduced Ipeak but did not cause large RMP changes. Porcine non-pigmented epithelial cells (pNPE) in normal conditions display no Ipeak, small Iss, small RMP near -20 mV and spontaneous Cx43 hemichannel-like event activity. Nevertheless, GSK caused further depolarization of pNPE cells, and while no gm changes were seen when GSK was applied while holding cells at -50 mV, gm did increase when GSK exposure occurred during repeated ±80 mV pulses. Preliminary experiments show that activation of TRPM3 by its agonist pregnenolone causes a minimal hyperpolarization in mLEC. In comparison, in a line of human LEC (HLE B3) expressing TRPM3 channels, and which appear generally depolarized, pregnenolone caused a proportionally larger shift toward more negative RMP values; more intriguing, GSK has no measurable effect on the gm of HLE B3 cells. Taken together, and apart from considerations of cell- and species-specific differences, the data suggest that mechanosensor channels have different and/or opposite effects on the regulation of membrane ion channel activity, and thus on cell function.

R01EY029171 and R01EY009532.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Time-Restricted Feeding Induces Beiging and Rejuvenates Adipose Tissue with Beneficial Effects on Cerebral Function in Old Mice
Authors: Reyff Zeke , Sanford Madison , Negri Sharon , Ballard Cade , Balasubramanian Priya , Tarantini Stefano
Published: May 2024

Adipose tissue, traditionally viewed as purely an energy reserve, has recently been unveiled as a critical endocrine organ. Through the secretion of bioactive molecules known as adipokines, adipose tissue plays a role in inter-organ communication, most notably with the brain to maintain metabolic homeostasis and cognitive function. Aberrant adipokine secretion or signaling, often exacerbated with aging, has emerged as a defining characteristic of dysfunctional adipose tissue. This dysregulation can lead to inflammatory conditions, potentially disrupting neural homeostasis and heightening the vulnerability of older individuals to cognitive impairments. This study investigated the capacity of time-restricted feeding (TRF) to promote beiging (induction of brown adipocytes positive for uncoupling protein 1(UCP1) within white adipose tissue depots) in aged mice, exploring its potential role in modulating adipokine profiles, attenuating inflammation, and mitigating age-associated cognitive decline. To test this hypothesis, we collected adipose tissue samples from 24-month-old mice that underwent 6 months of TRF and compared their profiles to both young and age-matched controls on an unrestricted (ad-lib) diet. Immunohistochemical analyses of brown adipose tissue (BAT), subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) revealed a marked reduction in pro-inflammatory markers CD80 and F4/80hi across all adipose tissues. Notably, a shift towards an anti-inflammatory state was indicated by a pronounced increase in CD163 staining in the SAT and VAT. Additionally, the increased expression of UCP1, especially in BAT and SAT, pointed towards an enhanced thermogenic capacity, suggesting a potential metabolic advantage. This was further reinforced by an increase in electron transport chain (ETC) activity in all adipose tissues. These findings have powerful implications given the established links between systemic inflammation, disrupted adipokine signaling, and neurodegenerative conditions. The alleviated adipose inflammatory profiles measured in TRF mice not only underscore its potential metabolic benefits but also highlight its possible role in safeguarding cognitive health, especially in an aging demographic. Currently serum studies and RNA sequencing are being conducted to look at altered transcript production and to investigate the role of adipokines on the brain health of the aged TRF mice. Such insights pave the way for future research exploring dietary strategies to combat age-related cognitive decline.

Stephenson Cancer Center, National Institute on Aging R03 AG070479, American Heart Association.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Nodose afferent fibers require PIEZO2 for esophageal mechanosensation
Authors: Nair SANJAY S , Hadley Stephen , Patil Mayur , Taylor-Clark Thomas
Published: May 2024

The esophagus receives dual innervation of extrinsic afferent fibers from both the dorsal root ganglia as well as the vagal ganglia. These are polymodal sensory afferents that are able to sense a variety of stimuli that include chemical and mechanical stimuli. Previous research has demonstrated that the esophagus is innervated by low threshold mechanoreceptors arising from the nodose ganglia, which provide critical peripheral feedback that is required for proper swallowing and peristaltic reflexes. We know that in the vagal system, PIEZO2 plays a critical role in lung inflation and baroreceptor function in the aorta and carotid sinus. Hence, we hypothesize that PIEZO2 is the mechanotransducer in these nodose esophageal low threshold mechanoreceptors. We used a two-pronged approach to elucidate PIEZO2’s role in esophageal mechanosensation: first, GCaMP6s imaging and then single fiber electrophysiology to understand the kinetics of nodose esophageal afferent fiber activation. Both of these approaches used our ex-vivo intact vagal esophageal preparation. Our proof-of-principle studies were conducted in PIRT-GCaMP6s mice, obtained through the crossbreeding of Pirt-Cre (Cre expressed in all sensory neurons) mice with Cre-dependent, ROSA26 based, GCaMP6s reporter (B6.129S6-Gt(ROSA)26Sor-tm96(CAG-CGaMP6s)Hze). Our preliminary data in Pirt-GCaMP6s mice showed a profound increase in the Ca2+ influx in a subset of nodose neurons in response to mechanical distention of the esophagus at 5, 10, and 30mmHg pressures. For our knockout group, we obtained nodose-specific knockout of PIEZO2 by crossing P2X2-Cre mice (P2X2 is expressed in all nodose neurons) with PIEZO2fl/fl mice (P2X2/PIEZO2 KO mice). Upon performing our GCaMP6s imaging experiments in this group, we saw that there was a significant reduction in the number of nodose neurons that were responsive to esophageal distention (58% down to 17%). Comparing the fluorescence intensities of all esophageal neurons between the control and KO groups, we observed a significant reduction at all three intraesophageal pressures (p<0.05, n=458 and 395 neurons in control and KO groups, respectively). In our single fiber electrophysiology experiments, our control and KO groups were PIEZO2fl/fl mice and P2X2/PIEZO2 KO respectively. We were able to successfully record APs from A-fiber mechanosensitive esophageal neurons. The number of APs recorded from KO group was reduced at all the three intraesophageal pressures when compared to the control PIEZO2fl/fl mice. Our findings support the hypothesis that PIEZO2 is the mechanotransduction protein involved in vagal nodose afferent fibers innervating the esophagus.

NIH.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Pulmonary Embolism Increases the Risk of Dyspnea in Pediatric Patients
Authors: Abidan Abulimiti , Robson Lydia , Pawelczyk James , Balmain Bryce N. , Babb Tony G. , Zia Ayesha
Published: May 2024

This study investigated the association between pulmonary embolism (PE) and a subsequent diagnosis of dyspnea in pediatric patients using real world population-based data. We collected de-identified data from TriNetX, a global federated multicenter research database using both UTSouthwestern (UTSW) and Multinational Research Network. Patient ages of 8 to 21 with and without a diagnosis of pulmonary embolism (ICD-10-CM I26) were examined for associations with a new diagnosis of dyspnea (ICD-10-CM R06.0) three or more months after their initial PE diagnosis. The prevalence of PE significantly increased the risk for a new diagnosis of dyspnea after their initial PE diagnosis among all patients in the UTSW Network (risk ratio: 5.00) and Research Network (risk ratio: 6.55). In the Research Network, this risk was significantly higher for females than males (risk ratio: 6.06 Vs. 5.08) (all p<0.001). These findings suggesting that clinicians should consider PE as an independent risk factor for diagnosis of dyspnea in pediatric patients.

Supported in part by NHLBI R38HL150214 (PI: Susan Hedayati).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
N-Methyl-D-aspartic acid (NMDA) mediated vasodilation in aorta
Authors: Yilmaz Gokhan , Alexander J. Steven
Published: May 2024

Although N-Methyl-D-aspartic acid (NMDA) mediated vasodilation has been extensively studied in cerebral circulation, there are limited studies that address the NMDA-mediated vascular responses at the peripheral vascular system. In this study our objective is to address the peripheral vascular responses mediated by NMDA. Vascular responses were obtained via in vitro myography on thoracic aorta segments isolated from C57BL/6 wild type male mice. NMDA at the concentration range of 100 micromolar to 1 millimolar in aortic segments precontracted by 1 micromolar phenylephrine. Maximal vasodilation of 75% in reference to baseline prior to drug application was observed at 3mM NMDA. NMDA receptor blockade by MK-801 did not change NMDA-induced vasodilation (55% vs 58%). Neither vehicle of NMDA, nor corresponding osmolar solutions of mannitol to NMDA concentrations induced vasodilation. Nitric oxide synthase (NOS) inhibition by 100 micromolar m Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) reduced 3mM NMDA induced vasodilation from 75% to 16%. Removal of endothelial cell layer did not change the vasodilation mediated by NMDA. NMDA at millimolar concentrations relaxes vascular smooth muscle via non-endothelium dependent and NMDA-receptor independent mechanisms. Vasodilatory response to NMDA appears partially mediated by NOS. It is possible that NMDA is exerting its vasodilatory effects via non-NMDA receptors on the vascular smooth muscle. Whether NMDA-induced vasorelaxation is observed in resistance arteries remains warranted.

PSC CUNY 66608-00 54.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Myeloid Ptpn2 Deficiency in Mice Causes Functional Iron Deficiency
Authors: Lei Hillmin , Spalinger Marianne , Santos Alina , Crawford Meli'sa , Shawki Ali , McCole Declan
Published: May 2024

Background: Anemia is the most prevalent extraintestinal complication of inflammatory bowel disease (IBD) and is associated with the manifestation of Crohn’s disease. Anemia significantly reduces the quality of life, increases hospitalization visits, and increases medical care expenses of IBD patients. Iron deficiency is the leading cause of anemia in IBD; however, the physiological mechanisms involved are still poorly understood. Macrophages significantly contribute to iron homeostasis by mechanisms including iron recycling by phagocytosing senescent erythrocytes and damaged cells, and nurturing erythropoiesis in the bone marrow. In this study, we investigated the role of the IBD candidate gene, protein tyrosine phosphatase non-receptor type 2 ( PTPN2), in regulating macrophage iron homeostasis. Methods: Myeloid cell-specific knockout mice ( Ptpn2LysMCre) and control littermates ( Ptpn2fl/fl) were analyzed for serum iron content and liver and spleen non-heme iron. Duodenal epithelial cell (DEC) proteins were assayed by Western blotting. Localization of the brush border ferrous iron transporter, DMT1, and the coupled ferrous iron absorption driver, NHE3, in duodenal tissue was determined by immunohistochemistry (IHC). Gene expression profiles of macrophages were analyzed by Nanostring. Results: Ptpn2LysMCre mice had reduced serum iron ( p<0.0001; n=12) and reduced spleen non-heme iron (p=0.0017; n=6), whereas liver non-heme iron was unaltered (n=6), indicating iron deficiency in select tissues. DMT1 (n=8) and NHE3 (n=5) protein expression in DECs was unaltered and IHC confirmed the unaltered localization of DMT1 and NHE3 (n=6) in the duodenal epithelium of Ptpn2LysMCre mice, suggesting the reduction in serum iron was not due to an impairment in intestinal non-heme iron uptake. Nanostring analyses revealed that the gene expression of the iron transporter Dmt1, iron exporter Fpn, and iron importer Tfr1 were significantly downregulated (p<0.05; n=5) in macrophages from Ptpn2LysMCre mice, indicating an iron sequestering phenotype. Conclusions: Loss of myeloid Ptpn2 in mice causes functional iron deficiency. These findings indicate a major role of myeloid PTPN2 in regulating systemic iron homeostasis.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Liposomal Nanocarriers of Preassembled Glycocalyx Restore Venular Permeability in Sepsis: Assessed Quantitatively with a Novel Microchamber System
Authors: Ishiko Shinya , Koller Akos , Deng Wensheng , Huang An , Sun Dong
Published: May 2024

Background: The endothelial glycocalyx (EG), covering the luminal side of endothelial cells, regulates vascular permeability and senses wall shear stress. In sepsis, EG undergoes degradation leading to increased permeability and edema formation. We hypothesized that restoring EG integrity using liposomal nanocarriers of preassembled glycocalyx (LNPG) will restore normal venular permeability in a lipopolysaccharide (LPS)-induced sepsis model of mice. Methods: To test this hypothesis, we designed a unique perfusion microchamber in which the vascular permeability of isolated and cannulated mice mesenteric venules could be assessed by measuring the concentration of Evans blue dye (EBD) by fluorescent spectroscopy in microliter-samples of extravascular solution (ES). Results: Histamine-induced time- and dose-dependent increases in EBD in the ES could be measured, confirming the sensitivity of the microchamber system. Notably, the histamine-induced increase in permeability was significantly attenuated by histamine receptor (H1) antagonist, triprolidine hydrochloride. Subsequently, mice were treated with LPS, or LPS + LNPG. Compared to control mice, venules from LPS-treated mice showed a significant increased permeability, which was significantly reduced by LNPG administration. Moreover, in the presence of wall shear stress, intraluminal administration of LNPG significantly reduced the permeability in isolated venules from LPS-treated mice. Conclusion: Our newly developed microchamber system can quantitatively measure the permeability of isolated venules. LPS-induced sepsis increases permeability of venules that is attenuated by in vivo LNPG administration, which is also reestablished endothelial vasomotor responses to shear stress. Thus, LNPG presents a promising therapeutic potential for restoring EG function and thereby mitigating the increased permeability in sepsis.

Support: National Institute of Health [grant number: HL144528, Dong Sun] and the Uehara Memorial Foundation [grant number: 202241049, Shinya Ishiko) and Hungarian Academy of Sciences Post-Covid 2021-34 (AK) and MIT of Hungary, National Research, Development, and Innovation Fund, OTKA K 132596 (AK).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Discovery and mechanistic studies of a novel BKCa channel modulator inducing long openings
Authors: Lee Na Young , Jung Jun-Hyung , Lee Narasaem , Park Chul-Seung
Published: May 2024

The large-conductance Ca2+-activated K+ channel (BKCa channel) plays critical roles in various tissues. In the smooth muscle of the urinary bladder, BKCa channel is highly expressed and regulates the spontaneous action potentials that control muscle contraction. Thus, the chemical activators for BKCa channel have their therapeutic potential against overactive bladder syndrome. Preveiously, we conducted a screening of a chemical library comprising 9,938 compounds in search of novel activators of the BKCa channel and performed structure-activity relationship study through hit compounds by using a cell-based fluorescence assay. Among the optimized compounds, DBTB-1 (N-[4-(2,4-dimethyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-6-yl)-1,3-thiazol-2-yl]benzamide) displayed a robust activation of macroscopic BKCa channel currents in Xenopus oocytes. In contrast to other BKCa channel activators, DBTB-1 mainly influenced deactivation kinetics of the channel without affecting channel activation significantly. At the single-channel level, DBTB-1 increased the open-state probability compared to vehicle without affecting its single-channel conductance, indicating the delayed closing of the channel in the presence of the drug. Furthermore, analysis of the open dwell-time showed an additional population of long openings induced by DBTB-1. Thus, these unique characteristics of DBTB-1 can be useful in designing a new class of BKCa channel activators and might be utilized in developing therapuetics targeting specific aspect of the channel function.

This research was supported by Korea Drug Development Fund funded by Ministry of Science and ICT, Ministry of Trade, Industry, and Energy, and Ministry of Health and Welfare (RS-2023-00258812).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.