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Tandem exposure to cannabinoids and nicotine during pregnancy poses significant risks to fetal development and health including low birth weight, preterm birth, and perinatal death. However, the effect of co-exposure with the most prominent cannabinoids found in Cannabis sativa (Trans-Δ-9- tetrahydrocannabinol (THC) and cannabidiol (CBD)) alongside nicotine on fetal lung development is not well understood. This study aims to investigate the combinatorial impact of CBD, THC, and nicotine, on human lung development through investigating cellular senescence and the potential role of senolytics in alleviating these effects. Human fetal lung explants from 10 to 16 weeks gestation were cultured on air-liquid interface and treated with various concentrations of nicotine (1µM), CBD, and THC (5µM, or 2.5µM each when used in combination), for 72 hours. To assess the effect of senolytics, the explants were also treated for 48 hours with a combination of CBD, THC, and nicotine. Subsequently, senolytics, Dasatinib (D, 250nM) and Quercetin (Q, 375nM), were added or not for an additional 24 hours. After the 72-hour treatment, explants were collected and either fixed for immunofluorescence staining (IF) analyses or used for RNA extraction and quantitative reverse transcription PCR (qRT-PCR). Additionally, the supernatants were used to evaluate the expression of the senescence-associated secretory phenotype (SASP), conducted by Eve Technologies Corporation-Canada. This study used Luminex xMAP technology for multiplexed quantification of 96 Human cytokines, chemokines, and growth factors. Our results demonstrated that co-exposure to CBD, THC, and nicotine increases the expression of the senescence markers CDKN1A (0.1163±0.02384, p=0.0094, n=8) and CDKN2A (0.005793±0.002157, p=0.0516, n=8) encoding P21 and P16 respectively. Moreover, the IF staining showed increased expression of the DNA damage marker γH2A.X following treatment with CBD+THC+nicotine (7.375±2.154% vs 2.245±0.8329%, p=0.0604, n=6). Furthermore, the lung explants treated with cannabinoids and nicotine released cytokines and chemokines involved in immune responses and inflammation among others IL-6, IL-8, M-CSF, MCP-3, MIP-1β, TNFα, MIP-3β, and TSLP (p<0.05). The addition of D+Q reduced SASP secretion and showed a decreasing trend in expression of the senescence genes CDKN1A and CDKN2A compared to the triple treatment. Taken together, our results showed that the combinatorial exposure to CBD, THC, and nicotine increases senescence, DNA damage, and the senescence-associated secretory phenotypes (SASP) secretion. The use of senolytics (D+Q) may prove to be a promising therapeutic option, alleviating several of the negative effects induced by the different substances. RO1HL171915-01A1 RO!HL155104 RO1HL158532-03 ROIHL160570 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Vitamin D (VitD) is an essential nutrient for preventing rickets in breastfeeding infants. Maternal supplementation is the preferred method for infant nutrition, yet concentrations of VitD and 25-hydroxyvitamin D (25OHD) in breastmilk are low unless the mother consumes substantial doses of vitamin D. Recently, we reported that sulfate-conjugated forms of vitamin D (VitD-S) and 25-hydroxyvitamin D (25OHD-S) are present in breast milk. Freshly expressed breast milk from mothers who were vitamin D-sufficient (serum 25OHD >50 nmol/L) contained approximately 6 nmol/L VitD-S and 0.5 nmol/L 25OHD-S. It is hypothesized that these sulfated metabolites are contributing to the total vitamin D nutritional value of milk; however, their physiological roles in infant nutrition are not yet understood. In order to assess their nutritional value, we evaluated two aspects that can affect the delivery and uptake of the nutrients by infants: breast milk storage and infant digestion. The United States Centers for Disease Control and Prevention recommends that breast milk can be stored safely at room temperature (22°C) for ≤4 hours, in refrigeration (4°C) for <4 days, or frozen (-20°C) for 6 months. After implementing the recommended storage conditions on breast milk samples, the metabolites, VitD-S and 25OHD-S, were measured by LC-MS/MS and UV spectroscopy. We observed that in breast milk stored at room temperature or 4°C, the metabolites undergo molecular degradation by isomerization within 24 hrs. Therefore, breast milk stored overnight (>8 h) in refrigeration will not provide the sulfated vitamin D metabolites to the infants. To evaluate molecular integrity of the sulfated metabolites during infant digestion, we collected saliva and fecal matter samples from infants, 1-6 months of age, who were either exclusively breastfed or breastfed and supplemented with formula ( ClinicalTrials.gov , NCT 06203041). The sulfatase enzymatic activity was assessed in the saliva and fecal matter samples by colorimetric assay. Overall, the sulfatase activity (mean ± SD) in saliva was 0.8 ± 0.7 nM/mg/min, ranging 0.0-2.5 nM/mg/min (n=13). The sulfatase activity in fecal samples was significantly greater than saliva ( P = 0.009), averaging 1.8 ± 1.4 nM/mg/min and ranging 0.1-4.9 nM/mg/min (n = 9) across infant samples. In a comparison between infants based on diet, we observed greater sulfatase activity in the fecal matter of exclusively breastfed infants than in infants that were breastfed with formula ( P = 0.056). This observational study is ongoing and not yet statistically powered. The presence of sulfatase activity in the infant digesta suggests that VitD-S and 25OHD-S are subject to enzymatic sulfate hydrolysis prior to absorption. Furthermore, infants who are exclusively breastfed may utilize the hydrolysis pathway more effectively than infants who are supplemented with formula. In summary, the nutritional value of VitD-S and 25OHD-S is affected by both milk storage and infant digestion. Future clinical studies investigating vitamin D nutrition in breastfed infants should consider evaluating storage of breast milk and diet of the infant as important parameters in the statistical models and analyses. The Mayo Clinic Parker D. Sanders & Isabella G. Sanders Professor of Family Medicine Endowment, Mayo Clinic Women’s Health Center Pilot Award Project. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Obesity is a prevalent metabolic condition that is strongly associated with the development of cardiovascular disease. Adipose arteries exhibit robust endothelial dysfunction in diet-induced obese mice. Obesity is also associated with elevated plasma long chain fatty acids (LCFAs), well-established contributors to endothelial dysfunction, which require a receptor to facilitate their uptake. CD36, facilitates LCFA uptake which when in excess contributes to endothelial dysfunction. Our previous work demonstrated that global CD36 ablation restores endothelium-dependent dilations to flow. Therefore, to determine if an upregulation in CD36 expression was driving these differences, we first assessed if obesity alters endothelial CD36 expression using flow cytometry and immunofluorescence imaging. For flow cytometry experiments mesenteric arteries were digested and sorted to identify the endothelial cell population (i.e., CD45-CD31+ cells). En face preparations were stained for VE-cadherin to locate the endothelial cell layer using confocal microscopy. In both experiments, an antibody that detects an extracellular epitope of CD36 was used to detect membrane expression. Obesity did not alter the expression of CD36 in endothelium of mesenteric arteries relative to lean counterpart controls in WT mice. We next aimed to determine if obesity influences the functional capacity of endothelial CD36. First, we measured LCFA uptake in mesenteric arteries from lean and obese WT mice. Arteries were exposed to a fluorescent palmitic acid analogue, BODIPYC-16, and internalized endothelial LCFA uptake was assessed at different time points using confocal microscopy. Arteries from obese mice had elevated endothelial LCFA uptake and lipid accumulation relative to lean controls. To determine if the effects of obesity on LCFA uptake were mediated by endothelial CD36, we repeated the fluorescent LCFA uptake experiments using the Tie2eCreCD36 fl/fl model. First, to determine if endothelial cell CD36 was driving obesity induced endothelial dysfunction, mesenteric arteries were isolated from lean and diet-induced obese Tie2eCreCD36 fl/fl mice. Arteries from Tie2eCreCD36 fl/fl diet induced obese mice exhibited attenuated fatty acid uptake, compared to their lean and obese genotype controls. Next, we measured endothelial function ex vivo via pressure myography. Mesenteric arteries from obese Tie2eCreCD36 fl/fl mice exhibited a restored response to flow induced vasodilation relative to respective controls suggesting a role for endothelial cell CD36 in mediating endothelial dysfunction perhaps through promoting lipid accumulation in obesity. Ongoing work within our lab is aimed at determining the mechanism underlying obesity-induced alterations to endothelial CD36 and how the observed increase in LCFAs may be contributing to reduced endothelial function. Center of Biomedical Research Excellence in Cardiovascular Health (COBRE): 5P20GM113125-08, University of Delaware Research Fund (UDRF) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

SLC26A9 is a Cl - channel and electrogenic Cl - -HCO 3 ‑ exchanger found in several human epithelia, including the lung, intestine / GI tract, and kidney. SLC26 proteins are defined by a C-terminal, cytoplasmic sulfate transporter / anti-σ-domain (STAS). In mammals, several STAS domains have protein-protein interactions with the regulatory-region of CFTR (R-CFTR), the Cl - channel associated with cystic fibrosis. However, the functional consequences, i.e., regulatory effects (up/downregulation), of STAS-to-R-CFTR binding seem to differ by SLC26 member. Our prior work showed that the SLC26A9:CFTR interaction decreases SLC26A9 channel and exchange activity. If SLC26A9-STAS was replaced with SLC26A6-STAS, no inhibition of SLC26A9 conductance occurred when interacting with R-CFTR (PMID 19643730). Complete deletion of SLC26A9-STAS removed Cl - conductance. Thus, we hypothesized that a disordered loop within STAS is the likely interaction area, and therefore deleted this STAS-disordered loop (ΔLoop) to test this region’s functionality. We used a voltage clamp to measure Cl - currents (IV; conductance G calculated) in Xenopus laevis oocytes (n=10 / construct) injected with cRNA of ΔLoop and subcomponent areas of SLC26A9. Each construct contained a 3xFLAG tag such that stained oocytes from these constructs allowed determination of membrane expression. ΔLoop has three subregions: K/R rich, Middle, S/T rich. Both ΔLoop and ΔLoop(K/R) increase Cl - currents (and conductance) by 5x greater comparted to wild-type SLC26A9. Five amino acid extension of ΔLoop (N- or C-terminal) produces Cl - currents equivalent to ΔLoop deletion. However, 10 amino acid extension of ΔLoop (N- or C- direction) produces currents equivalent to WT-SLC26A9. Membrane localization indicates that ΔLoop and regional deletion constructs have similar membrane abundance to WT, while boundary deletions inhibit channel trafficking to the membrane. As ΔLoop(S/T) slightly increased conductance, the ordered S/T-rich motif [T 620 SVSYITFS 628 ] was examined for possible phosphorylation effects by serial alanine substitution. Each alanine substitution in the S/T-rich motif decrease SLC26A9 Cl - conductance vs WT-SLC26A9. However, for S623A the conductance decrease was due to minimal plasma membrane expression rather than apparent change of channel activity. Together these data suggest that the disordered loop is multifaceted and can maintain low conductance (autoinhibition) or by potential phosphorylation. As cystic fibrosis (CF) results from loss-of-function, trafficking or degradation mutations, the robust Cl - conductance from elimination of SLC26A9 autoinhibitory, disordered loop, presents an opportunity to supplement or replace Cl - conductance in CF tissues and potentially patients. R25-DK101405 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Phrenic motor neurons (PhMNs) innervate the diaphragm muscle (DIAm), the primary pump muscle involved in breathing. It has been shown that brain-derived neurotrophic factor (BDNF) signals through its high-affinity, full-length tropomyosin receptor kinase B (TrkB.FL) to promote PhMN survival in embryonic and early postnatal development. Reduced BDNF/TrkB.FL signaling also appears to be involved in the age-related loss of PhMNs. Previously, we developed a novel chemogenetic rat model ( TrkB F616 rat) in which insertion of a knock-in allele sensitive to 1NMPP1 (a selective kinase inhibitor) allows rapid inhibition of TrkB.FL kinase activity. Using this TrkB F616 rat, we found that in younger animals, a 14-day period of 1NMPP1-induced TrkB.FL kinase inhibition resulted in an ~20% loss of larger PhMNs similar to that found with aging. Previous studies from our laboratory demonstrated that BDNF/TrkB.FL signaling induces pCREB S133 phosphorylation at serine residue 133 in PhMNs. 1NMPP1 induced inhibition of TrkB.FL kinase activity in TrkB F616 rats acutely blunts pCREB S133 phosphorylation induced by intrathecal BDNF treatment. In another cell type, we showed that pCREB S133 transcriptionally targets PGC1α expression with downstream upregulation of expression of mitochondrial transcription factor A (TFAM) and mitochondrial biogenesis. Based on a bioinformatic analysis, we identified a putative binding site for pCREB S133 in the rat PGC1α promoter. In the present study, we hypothesized that BDNF/TrkB.FL signaling mediates pCREB S133 phosphorylation and downstream activation of PGC1α thereby promoting mitochondrial biogenesis. Adult female and male TrkB F616 rats (~ 3 months of age; 300 g) were anesthetized (ketamine/xylazine) and either 25 μM 1NMPP1 or DMSO (vehicle control) was injected ip. After 2 h, the rats were treated intrathecally (infused at C 4 ) with 100 ng/ml BDNF for 40 min. Thereafter, the animals were euthanized and the ventral cervical spinal cord containing PhMNs was dissected, and lysates were prepared for subsequent analyses. Western blot was performed to quantify pCREB S133 phosphorylation, and PGC1α mRNA and protein expression were measured by qPCR and Western blot, respectively. A chromatin immunoprecipitation (ChIP) assay confirmed that pCREB S133 binds to the PGC1α promoter and that compared to vehicle treated controls, 1NMPP1induced TrkB.FL kinase inhibition reduced the binding affinity of pCREB S133 . Consistent with these results, we found that pCREB S133 phosphorylation and PGC1α mRNA and protein expression were reduced following 1NMPP1-induced TrkB.FL kinase inhibition. We conclude that in the rat cervical ventral horn, BDNF/TrkB.FL signaling induces pCREB S133 phosphorylation which transcriptionally activates PGC1α expression and downstream mitochondrial biogenesis. The BDNF/TrkB.FL signaling pathway acting in concert with activity dependent signaling may converge on pCREB S133 phosphorylation to maintain the survival of PhMNs by promoting mitochondrial biogenesis. The loss of the contribution of BDNF/TrkB.FL signaling in old age and with neurodegeneration may lead to PhMN death. Supported by NIH grants AG44615 and HL146114 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

In the elderly, age-associated muscle weakness and atrophy (sarcopenia) is prevalent in both limb and respiratory muscles. In the tongue muscles, dyscoordination and sarcopenia predisposes elderly individuals to dysphagia, dysphonia and a greater risk for aspiration pneumonias and obstructive sleep apnea. In humans and in the Fischer 344 rat model of aging, motor neuron (MN) death occurs in old age, and the selective vulnerability of fast-fatigable motor units to loss is consistent with behavioral deficits in airway defense (e.g., cough). However, whether the timing of MN loss is gradual across the lifespan or precipitous from late-middle-age is unknown. Recently, the concept of an age -related increase of systemic inflammatory cytokines has been implicated in the development of sarcopenia, although the mechanisms by which this occurs remain obscure. In other cell types, inflammation triggers an unfolded protein response and mitochondrial fragmentation – processes implicated in neuronal death and neurodegeneration. In this study of female and male Fischer 344 rats at 6-, 18- and 24-months-old, we evaluated serum inflammatory cytokines (TNFα, IL1β & IL6) via ELISA, medullary unfolded protein response (pIRE1a S724 & CDK5) and mitochondrial fragmentation (pDRP1 S616 ) via Western blot, hypoglossal MN mitochondrial volume density and mitochondrial fragmentation via serial blockface electron microscopy (SBFEM), hypoglossal MN survival via Nissl histology and stereological counting and tongue muscle (longitudinal and genioglossus) sarcopenia via uniaxial specific force assessment and cross-sectional muscle fiber areas. All data were analyzed by 1-way ANOVAs or Kruskal-Wallis nonparametric tests, depending on data distributions. Here, we show that a systemic inflammation-induced unfolded protein response in the medulla and hypoglossal MNs mitochondrial fragmentation is present at 18-months-old. This mitochondrial fragmentation is consistent with increased medullary expression of pDRP1 S616 . At this age, we did not observe any evidence of tongue muscle weakness or atrophy, nor any evidence of hypoglossal MN death. At 24-months old, hypoglossal MN mitochondrial deficits remained readily observable using SBFEM, with hypoglossal MN death (specific to larger MNs) and tongue muscle sarcopenia (selective to fast-fatigable type IIx fibers) present at this age. Overall, we conclude that denervation-related sarcopenia is precipitous from late-middle-age to old age in Fischer 344 rats. This MN death is triggered (or at least preceded), by an unfolded protein response and mitochondrial fragmentation. Interventions ameliorating inflammation, the unfolded protein response and/or mitochondrial breakdown may preserve MNs and prevent or reduce age-associated sarcopenia. This work was supported by NIH grants: HL166204 (MJF), AG086136 (MJF), HL157984 (GCS) & AG44615 (GCS) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Age-associated muscle weakness and atrophy (sarcopenia) is prevalent in both limb and respiratory muscles. In the tongue muscles, dyscoordination and sarcopenia predisposes elderly individuals to dysphagia, dysphonia and a greater risk for aspiration pneumonias and obstructive sleep apnea. In humans and in the Fischer 344 rat model of aging, motor neuron (MN) death occurs in old age, and the selective vulnerability of fast-fatigable motor units to loss is consistent with behavioral deficits in airway defense (e.g., cough). However, in many aerodigestive behaviors, deficits in neuromotor coordination and the timing of motor unit activations may be more pertinent than frank weakness. In motor neurons, the substrate for the integration of sensory, pattern, executive and reflex activations is the dendritic arbour. Currently, it is unknown whether MN dendritic and dendritic spine degenerations occur in aging and if any changes are specific to the vulnerable larger MNs. In this study of female and male Fischer 344 rats at 6- and 24-months-old, we evaluated hypoglossal MN dendritic arbours and dendritic spines using golgi-cox impregnation and confocal imaging approaches in thick brainstem vibratome ex vivo slices (200 µm). All data were analyzed by unpaired t-tests, 2-way ANOVAs or Pearson’s correlations, where relevant. In 24-month-old rats, hypoglossal MN dendritic arbour length and surface area were reduced compared to 6-month controls. In 6-month-olds, dendritic length and surface area was dependent on somal size, with bigger MN somas having longer and larger dendritic arbours, a relationship lost in 24-month old hypoglossal MNs. Dendritic spine density was reduced in 24- compared to 6-month-old rats. Overall, our findings suggest that hypoglossal MN dendritic degenerations with aging are selective to MNs of fast-fatigable motor units. Interventions ameliorating neuromotor circuit and dendritic breakdown may preserve neuromotor function in old age. This work was supported by NIH grants: HL166204 & AG086136 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction: Regulation of cerebral blood flow (CBF) is vital for ensuring blood supply to cerebral tissue, and studies have shown that CBF increases to match the demands of whole-body exercise. Additionally, studies have shown that an inspiratory muscle metaboreflex induced by fatiguing inspiratory work causes a decrease in blood flow to limbs and splanchnic organs, presumably redirecting blood flow to the activated inspiratory muscles. However, it is unknown if the metaboreflex response is greater when targeting the diaphragm during inspiration as opposed to using all inspiratory muscles. We aimed to determine if middle cerebral artery velocity (MCAv), a surrogate for global CBF, was affected by inspiratory muscle metaboreflex, and if so, if MCAv is affected differently when targeting diaphragmatic pressure (PTL-diaphragm; PTL di ) vs targeting mouth pressure (PTL-mouth; PTL mo ). We hypothesized that MCAv will be preserved with fatiguing inspiratory work, in both PTL di and PTL mo breathing patterns. Methods: We studied 11 (5 females) participants without any cardiorespiratory, metabolic, or musculoskeletal diseases (36±9 yrs, FEV 1 /FVC: 100±8%predicted). Each participant had gastric and esophageal balloon catheters placed to measure respiratory pressures. Blood pressure was continuously recorded via finger photoplethysmography. Transcranial doppler ultrasound continuously recorded MCAv. Participants performed breathing trials through a custom-built inspiratory pressure loading (IPTL) device, designed to open when negative pressure was generated. Each trial was comprised of 15 breaths/minute, with each breath consisting of 70% inspiration and 30% expiration. Trial 1 involved 5 minutes of PTL mo targeting 60% of their maximal inspiratory pressure, and trial 2 consisted of 5 minutes of PTL di targeting 60% transdiaphragmatic pressure. CO 2 was administered during IPTL to avoid hypocapnia. Cerebrovascular conductance index (CVCi) was calculated from MCAv. A paired t-test compared the 2 trials, deltas are calculated from end task to baseline, and data are reported as mean±SD. Results: The transdiaphragmatic pressures (PTP di ) between the two trials were different (PTL mo : 5,051±2,620, PTL di : 7,082±2,200 cmH 2 O·s/min; p=0.009). The change inMAP were not different between trials (PTL mo : 8±4, PTL di : 13±9 ΔmmHg; p=0.10). There was no difference in the change in MCAv (PTL mo : 10.07±21.51, PTL di : 9.66±22.10 Δcm/s; p=0.96) or CVCi (PTL mo : 0.03±0.23, PTL di : -0.01±0.17 Δcm/s/mmHg; p=0.55) between the two trials. Conclusion: These findings suggest that the inspiratory muscle metaboreflex does not impair CBF regulation during IPTL; this is true regardless of inspiratory muscle recruitment. Further work should focus on continuing the breathing exercises until exhaustion. NIH (HL139854); NSERC (PDF-577750-2023) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

CD40 signalling is involved in chronic inflammation, which is increasingly recognized as an important factor in initiation and progression of various cardiovascular diseases. Inhibition of the CD40-TRAF6 pathway was previously shown to be effective in preventing atherosclerosis and obesity in mice (Seijkens, JACC 2018, Chatzigeorgiou, PNAS 2014). In the present study we investigated the effect of CD40-TRAF6 inhibitor, compound 6877002 on left ventricular (LV) and coronary microvascular function in an adult swine model of familial hypercholesterolemia (FH). For this purpose, 10 adult male FH swine (3 years old, homozygous LDLR R84C mutation) received an atherogenic diet (10% lard and 0.75% cholesterol) for 9 months. During the last 3 months, 5 swine were subjected to treatment with the 6877002 compound (0.16 mg/kg i.v), while 5 animals received the vehicle i.v. At the end of treatment, swine were anesthetized and LV performance was studied under closed-chest conditions by pressure-volume loops constructed at baseline and during cardiac preload reduction. Subsequently, small coronary arteries (±250 μm diameter) were harvested from the LV and endothelium-dependent response to bradykinin in the presence and absence of endothelial nitric oxide (eNOS) blockade with LNAME, as well as endothelium-independent responses to the nitric oxide donor SNAP were studied in vitro. 6877002-treated animals showed a lower LV end-diastolic pressure (0±2 mmHg) as compared to vehicle-treated animals (6±1 mmHg, p≤0.05), and trends towards a reduced LV stiffness, reflected in a lower slope of the end diastolic pressure-volume relationship (sEDPVR: 0.16±0.02 mmHg/ml vs 0.20±0.01 mmHg/ml, p=0.07), and a higher ejection fraction (EF 46±2% vs 40±2%, p=0.08). Data from isolated small coronary arteries indicated that endothelium-independent vasorelaxation in response to SNAP was similar in both 6877002- and vehicle-treated animals, indicating unaltered vascular smooth smooth mucle cell responsiveness to NO. However, 6877002 treatment improved endothelium-dependent vasorelaxation to bradykinin (p≤0.05), as compared to vessels isolated from vehicle-treated animals. Moreover, eNOS blockade with LNAME blunted the endothelium-dependent vasorelaxation to bradykinin only in vessels from 6877002-treated animals, but not in those from the vehicle-treated swine, suggesting that NO bioavailability was completely lost in the vehicle-treated FH-animals, which was at least partially restored by treatment with 6877002 Conclusion: – Initation of CD40-TRAF6 pathway inhibition in adult FH swine receiving a high fat diet reduced LV end-diastolic pressure and enhanced LV passive compliance. The improved LV performance was accompanied by an amelioration of coronary microvascular endothelial dysfunction, characterized by the partial restoration of NO bioavailability. Funding: Grant 2020B008 RECONNEXT This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Objective: The recent advances in computational power have enabled the use of in-silico approaches in studying physiological flows. In this study, we aim to develop a digital twin of the human stomach, StomachSim, to simulate gastric biomechanics in case of motility disorders and surgery. Methods: A physiologically realistic model of the stomach, including the antral motility, is synthesized based on in-vivo imaging data. The mixing and gastric emptying are simulated using computational fluid dynamics (CFD). Fundic accommodation, terminal antral contraction, and the phasic opening of the pyloric sphincter are incorporated into the model. The enlargement and disruption of pyloric sphincter due to pyloric intervention procedures or pyloric incompetence is also implemented. The influence of food properties (density and viscosity), motility disorders (50% reduced amplitude of antral contractions), and pyloric intervention procedures on gastric mixing, duodenogastric reflux, and solid-food trituration is investigated. The gastric emptying rate and the transpyloric pressure gradient predicted by the model were in good agreement with existing in-vivo measurements in the literature. Results: Reduced antral motility led to inefficient mixing of gastric contents and 49% lower pressure forces and 33% reduced hydrodynamic shear stresses on solid food particles. In cases with pyloric incompetence, reduced motility resulted in 66% lower duodenogastric reflux rate. When the gastric contents were of higher viscosity, the proximal stomach applied a higher pressure to achieve the same emptying rate resulting in reduced duodenogastric reflux. Higher viscosity also led to over 7 times increased shear stresses on solid food particles. Food density, on the other hand, primarily affected the transport of refluxed contents – when the gastric contents were lighter, duodenal contents entering the stomach settled along the lower antrum, and when the gastric contents were heavier, the reflux contents were transported proximally towards the esophagus. Conclusion: The digital-twin model presented in this study allows the exploration of a wide set of parameters related to gastric function. Our simulations quantify the consequences of motility disorders on gastric digestion and duodenogastric reflux. The model also reports detailed force characteristics of solid food particles undergoing trituration. StomachSim offers a novel and potentially effective modality for examining the effect of gastric conditions and gastric surgical procedures on gastric function. The authors acknowledge support from NSF award CBET 2019405. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.