Abstract Maintaining cardiac structure and function throughout the lifespan requires a delicate balance in carbon allocation between energetic and biosynthetic processes. At the nexus of this balance are prohibitins (PHB1, 2), which form a ring-like complex in mitochondrial and plasma membranes responsible for coordinating cellular growth, metabolism and autophagy. Here we describe how ablation of the PHB complex in cardiomyocytes of adult mice (cPHB1KO) causes unrestrained mechanistic target of rapamycin complex 1 (mTORC1) activity and a ‘Warburg-like’ reprogramming of glucose metabolism in heart toward enhanced de novo amino acid biosynthesis. These changes are accompanied by disruptions in mitochondrial Ca 2+ handling and impaired autophagy, leading to severe dilated cardiomyopathy and mortality within 12 weeks. Using pharmacological and nutritional approaches, we further show that mTORC1 inhibition attenuates pathologic cardiac remodeling only in female cPHB1KO mice. Our findings illustrate novel mechanisms linking the PHB complex with altered carbon flux and pathogenesis of cardiomyopathy.

Despite major advances in medical therapies and prevention strategies, the risk of cardiovascular complications in patients with both type I and type II diabetes remains substantially elevated. In 2019, the American Heart Association sought applications for a Strategically Focused Research Network on Cardiometabolic Health and Type 2 Diabetes. In 2020, 4 centers were named, including Brigham and Women’s Hospital, Johns Hopkins University, New York University, and the University of Iowa. These centers performed basic, translational, and clinical studies to provide insights to explain the over 2-fold risk of cardiovascular complications in diabetes. Clinical studies and studies in cells and animals aimed to uncover new mechanisms responsible for disease development. Studies using human populations sought to uncover new biomarkers to prognosticate risk. In this review, we discuss several key issues and current and developing methods to understand why diabetes drives atherosclerotic cardiovascular disease and heart failure. Both human data and experimental models are considered. We integrate a review of these topics with work from the Strategically Focused Research Network and conclude with suggestions for identifying novel risk factors and future experimental research.

Sepsis is a life-threatening condition and the leading cause of mortality worldwide, particularly when an affected patient develops multiple organ dysfunction syndrome (MODS), a serious complication defined as progressive and potentially irreversible dysfunction in two or more organ systems. Clinical and experimental studies strongly suggest that patient outcomes with sepsis would improve if the risk for MODS and mortality could be identified in the first few hours after the onset of symptoms. We present an approach leveraging quartz crystal microbalance with dissipation monitoring (QCM-D) technology for rapid (∼30 min) detection of prohibitin-1 (PHB1), a protein with pleiotropic biological function that dramatically increases in blood during the acute phase of an infection. The feasibility of detection and reproducible quantification of recombinant PHB1 in physiological buffered conditions is described. Sensitivity and detection limit for the third overtone (12.19 Hz μg-1 mL and 59.06 ng/mL, respectively) were determined to be within the physiological range, highlighting the QCM-D immunosensor's potential for applied use in plasma samples. Importantly, there was strong concordance between PHB1 concentration curves generated using the QCM-D immunosensor and those from enzyme-linked immunosorbent assay (ELISA), which typically requires 36 h. Our findings illustrate a feasible and reproducible method to detect a bloodborne protein using immunosensor technology that has the potential to improve patient outcomes in sepsis and other serious infectious diseases.

Prohibitins (PHB1,2) are highly conserved lipid-raft associated proteins that physically interact to form a multimeric ring supercomplex in mitochondrial and plasma membranes where they are intimately involved in regulating cellular metabolism. Prior studies in disparate cell models have implicated PHB1 as a mediator of insulin signaling and its downstream effector, the mechanistic target of rapamycin complex 1 (mTORC1), but the mechanisms and physiological implications of these interactions are unclear. Here, we examined the role of PHB1 in regulating insulin and nutrient mediated activation of mTORC1 in liver using genetic and pharmacological approaches in mice and hepatocyte culture. Interestingly, male mice with hepatocyte-specific PHB1 haploinsufficiency (hPHB1-KD) at 6 months displayed features consistent with metabolic dysfunction-associated steatotic liver disease (MASLD), characterized by liver steatosis and impaired glucose tolerance with hyperinsulinemia, while these parameters were unaffected or even mildly improved in age-matched hPHB1-KD females. Both sexes of hPHB1-KD mice displayed increased basal phosphorylation of mTORC1 and its downstream targets (S6, 4EBP1) in liver compared with WT in fasted state, with minimal responsiveness to insulin. Transcriptomic data revealed strong upregulation of Lpin1 gene in male hPHB1-KD mice, a phosphatidic acid phosphatase regulated by mTORC1 that critically regulates hepatic lipid metabolism. Integrated transcript-/metabolomic analysis showed enriched glycerolipid metabolism and upregulation of MASLD pathway in the liver of hPHB1-KD males. Parallel experiments in AML12 hepatocytes confirmed that PHB1 knockdown causes hyper-activation of mTORC1 signaling, increased cytoplasmic lipin-1 expression and localization, and increased lipid droplet formation. Furthermore, one week of treatment with mTORC1 inhibitor Torin1 reduced hepatic triglycerides and normalized mTORC1 signaling in hPHB1-KD males to levels comparable with WT. Collectively, these findings demonstrate that PHB1 is essential for maintaining metabolic homeostasis in liver via control of mTORC1-lipin1 axis, and further confirm that metabolic effects of PHB1 deficiency in liver are sexually dimorphic.

BACKGROUND: Repeated use of addictive drugs produces long-lasting and prepotent drug-cue associations that increase vulnerability for relapse in individuals with a substance use disorder. Epigenetic factors, such as HDAC5 (histone deacetylase 5), play a key role in regulating the formation of drug-cue associations, but the underlying mechanisms remain unclear. METHODS: We used a combination of molecular biology, cultured cells, tandem mass spectrometry, deacetylase activity measurements, co-immunoprecipitation, and molecular dynamics simulations to assess HDAC5 structure-activity relationships. In male and female Long Evans rats, we used viral-mediated expression of HDAC5 mutants in the nucleus accumbens (NAc) to test effects on cocaine intravenous self-administration and cue-reinstated cocaine seeking. We also used in silico analysis of single-nucleus RNA sequencing data, quantitative reverse transcriptase-polymerase chain reaction, viral-mediated expression of Scn4b short hairpin RNA, patch-clamp electrophysiology, and rat cocaine or sucrose SA to assess Scn4b's effects on NAc intrinsic excitability and cued reward seeking. RESULTS: We discovered that 2 conserved cysteines located near HDAC5's catalytic domain were required for its intrinsic deacetylase activity and that HDAC5's deacetylase activity was required in NAc medium spiny neurons (MSNs) to limit relapse-like cue-reinstated cocaine seeking. Moreover, we found that HDAC5 limited cocaine-seeking, but not sucrose-seeking, behavior by reducing NAc MSN intrinsic excitability through the deacetylase-dependent repression of Scn4b, which codes for an auxiliary subunit of voltage-gated sodium channels. CONCLUSIONS: Our findings suggest that HDAC5's control of NAc Scn4b expression governs the formation of cocaine-cue, but not sucrose-cue, associations through modulation of NAc MSN intrinsic excitability and drug-induced NAc plasticity mechanisms.

Monoamine oxidase (MAO) helps regulate catecholaminergic signaling via metabolism of neurotransmitters epinephrine, norepinephrine, and dopamine—in turn producing the metabolites hydrogen peroxide (H2O2), ammonia (NH4+), and corresponding catecholaldehydes. While MAO has been a key facet of neuroscience and mood disorder research for > 60 years, MAO-generated metabolites have been largely overlooked until recently when reports have begun to illustrate the reactivity of these metabolites and their pathogenic contributions to disease (e.g., inflammation, fibrosis, cell death). These findings have extended MAO’s biological relevance beyond the brain and, most notably, to the heart, where a large and growing body of literature clearly indicates a pathophysiologic role for MAO-mediated catecholamine metabolism in heart disease. Herein, we discuss the evidence connecting MAO to various cardiac injuries and disorders, as well as describe the known cardiotoxicity associated with MAO’s reactive metabolites, specifically in connection to cardiac pathophysiology. Potential therapeutic strategies for targeting MAO and its metabolites to prevent and treat heart disease are also discussed, and important knowledge gaps highlighted. Created using biorender.com

Sarcopenia, or age-related muscle dysfunction, contributes to morbidity and mortality. Besides decreases in muscle force, sarcopenia is associated with atrophy and fast-to-slow fiber type switching, which is typically secondary to denervation in humans and rodents. However, very little is known about cellular changes preceding these important (mal)adaptations. To this matter, mitochondria and the sarcoplasmic reticulum are critical for tension generation in myofibers. They physically interact at the boundaries of sarcomeres, forming subcellular hubs called mitochondria-endo/sarcoplasmic reticulum contacts (MERCs). Yet, whether changes at MERCs ultrastructure and proteome occur early in aging is unknown. Here, studying young adult and older mice, we reveal that aging slows muscle relaxation, leading to longer excitation-contraction-relaxation (ECR) cycles before maximal force decreases and fast-to-slow fiber switching takes place. We also demonstrate that muscle MERC ultrastructure and mitochondria-associated ER membrane (MAM) protein composition are affected early in aging and are closely associated with the rate of muscle relaxation. Additionally, we demonstrate that regular exercise preserves muscle relaxation rate and MERC ultrastructure in early aging. Finally, we profile a set of muscle MAM proteins involved in energy metabolism, protein quality control, Ca2+ homeostasis, cytoskeleton integrity, and redox balance that are inversely regulated early in aging and by exercise. These may represent new targets to preserve muscle function in aging individuals.

Therapeutic efficacy of histidyl dipeptides such as carnosine is hampered by circulating carnosinase-1 (CN1), which catalyzes carnosine’s hydrolysis and degradation. Prior reports suggest that oral carnosine may improve cardiometabolic parameters in patients with heart failure (HF), but whether CN1 activity is affected by HF is unknown. Here, we measured CN1 content and carnosine degradation rate (CDR) in preoperative plasma samples from a cohort of patients (n = 138) undergoing elective cardiac surgery to determine whether plasma CN1 and/or CDR varied with left ventricular (LV) systolic dysfunction. CN1 content was normally distributed in the cohort, but plasma CDR displayed a quasi-bimodal distribution into high- (>2 nmol/(h*μL)) and low-activity (≤2 nmol/(h*μL)) clusters. Multivariable analysis confirmed female sex, diabetes and LV systolic dysfunction was associated with the low-activity CDR cluster. Although CN1 content did not differ, logistic regression analysis revealed that CDR and CN1-specific activity (CDR/CN1 content) was significantly lower in patients with both moderate (ejection fraction, EF ≥ 35 to <50%) and severe LV systolic dysfunction (EF < 35%) compared with patients in the normal range (EF ≥ 50%). These findings suggest that plasma CN1 activity is regulated by factors independent of expression, and that a decline in LV systolic function is associated with low CN1 activity. Further studies are needed to delineate specific mechanisms controlling CN1 expression and activity, which will facilitate the development of carnosine and other histidyl dipeptide therapies for cardiometabolic disorders such as HF.

Stearoyl-CoA desaturase-1 (SCD1) is a pivotal enzyme in lipogenesis, which catalyzes the synthesis of monounsaturated fatty acids (MUFA) from saturated fatty acids, whose ablation downregulates lipid synthesis, preventing steatosis and obesity. Yet deletion of SCD1 promotes hepatic inflammation and endoplasmic reticulum stress, raising the question of whether hepatic SCD1 deficiency promotes further liver damage, including fibrosis. To delineate whether SCD1 deficiency predisposes the liver to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC), we employed in vivo SCD1 deficient global and liver-specific mouse models fed a high carbohydrate low-fat diet and in vitro established AML12 mouse cells. The absence of liver SCD1 remarkably increased the saturation of liver lipid species, as indicated by lipidomic analysis, and led to hepatic fibrosis. Consistently, SCD1 deficiency promoted hepatic gene expression related to fibrosis, cirrhosis, and HCC. Deletion of SCD1 increased the circulating levels of Osteopontin, known to be increased in fibrosis, and alpha-fetoprotein, often used as an early marker and a prognostic marker for patients with HCC. De novo lipogenesis or dietary supplementation of oleate, an SCD1-generated MUFA, restored the gene expression related to fibrosis, cirrhosis, and HCC. Although SCD1 deficient mice are protected against obesity and fatty liver, our results show that MUFA deprivation results in liver injury, including fibrosis, thus providing novel insights between MUFA insufficiency and pathways leading to fibrosis, cirrhosis, and HCC under lean non-steatotic conditions.

Aims A mechanistic link between depression and risk of arrhythmias could be attributed to altered catecholamine metabolism in the heart. Monoamine oxidase-A (MAO-A), a key enzyme involved in catecholamine metabolism and longstanding antidepressant target, is highly expressed in the myocardium. The present study aimed to elucidate the functional significance and underlying mechanisms of cardiac MAO-A in arrhythmogenesis. Methods and results Analysis of the TriNetX database revealed that depressed patients treated with MAO inhibitors had a lower risk of arrhythmias compared with those treated with selective serotonin reuptake inhibitors. This effect was phenocopied in mice with cardiomyocyte-specific MAO-A deficiency (cMAO-Adef), which showed a significant reduction in both incidence and duration of catecholamine stress-induced ventricular tachycardia compared with wild-type mice. Additionally, cMAO-Adef cardiomyocytes exhibited altered Ca2+ handling under catecholamine stimulation, with increased diastolic Ca2+ reuptake, reduced diastolic Ca2+ leak, and diminished systolic Ca2+ release. Mechanistically, cMAO-Adef hearts had reduced catecholamine levels under sympathetic stress, along with reduced levels of reactive oxygen species and protein carbonylation, leading to decreased oxidation of Type II PKA and CaMKII. These changes potentiated phospholamban (PLB) phosphorylation, thereby enhancing diastolic Ca2+ reuptake, while reducing ryanodine receptor 2 (RyR2) phosphorylation to decrease diastolic Ca2+ leak. Consequently, cMAO-Adef hearts exhibited lower diastolic Ca2+ levels and fewer arrhythmogenic Ca2+ waves during sympathetic overstimulation. Conclusion Cardiac MAO-A inhibition exerts an anti-arrhythmic effect by enhancing diastolic Ca2+ handling under catecholamine stress.

Oral consumption of histidyl dipeptides such as l-carnosine has been suggested to promote cardiometabolic health, although therapeutic mechanisms remain incompletely understood. We recently reported that oral consumption of a carnosine analog suppressed markers of fibrosis in liver of obese mice, but whether antifibrotic effects of carnosine extend to the heart is not known, nor are the mechanisms by which carnosine is acting. Here, we investigated whether oral carnosine was able to mitigate the adverse cardiac remodeling associated with diet induced obesity in a mouse model of enhanced lipid peroxidation (i.e., glutathione peroxidase 4 deficient mice, GPx4+/−), a model which mimics many of the pathophysiological aspects of metabolic syndrome and T2 diabetes in humans. Wild-type (WT) and GPx4+/−male mice were randomly fed a standard (CNTL) or high fat high sucrose diet (HFHS) for 16 weeks. Seven weeks after starting the diet, a subset of the HFHS mice received carnosine (80 mM) in their drinking water for duration of the study. Carnosine treatment led to a moderate improvement in glycemic control in WT and GPx4+/−mice on HFHS diet, although insulin sensitivity was not significantly affected. Interestingly, while our transcriptomic analysis revealed that carnosine therapy had only modest impact on global gene expression in the heart, carnosine substantially upregulated cardiac GPx4 expression in both WT and GPx4+/−mice on HFHS diet. Carnosine also significantly reduced protein carbonyls and iron levels in myocardial tissue from both genotypes on HFHS diet. Importantly, we observed a robust antifibrotic effect of carnosine therapy in hearts from mice on HFHS diet, which further in vitro experiments suggest is due to carnosine’s ability to suppress collagen-cross-linking. Collectively, this study reveals antifibrotic potential of carnosine in the heart with obesity and illustrates key mechanisms by which it may be acting.

Lipid enals are electrophilic products of lipid peroxidation that induce genotoxic and proteotoxic stress by covalent modification of DNA and proteins, respectively. As lipid enals accumulate to substantial amounts in visceral adipose during obesity and aging, we hypothesized that biogenic lipid enals may represent an endogenously generated, and therefore physiologically relevant, senescence inducers. To that end, we identified that 4-hydroxynonenal (4-HNE), 4-hydroxyhexenal (4-HHE) or 4-oxo-2-nonenal (4-ONE) initiate the cellular senescence program of IMR90 fibroblasts and murine adipose stem cells. In such cells, lipid enals induced accumulation of γH2AX foci, increased p53 signaling, enhanced expression of p21 Cip1 , and upregulated the expression and secretion of numerous cytokines, chemokines, and regulatory factors independently from NF-κB activation. Concomitantly, lipid enal treatment resulted in covalent modification of mitochondrial proteins, reduced mitochondrial spare respiratory capacity, altered nucleotide pools, and increased the phosphorylation of AMP kinase. Lipid-induced senescent cells upregulated BCL2L1 (Bcl-xL) and BCL2L2 (Bcl-w). and were resistant to apoptosis while pharmacologic inhibition of BAX/BAK macropores attenuated lipid-induced senescence. In situ, the 4-HNE scavenger L-carnosine ameliorated the development of the cellular senescence, while in visceral fat of obese C57BL/6J mice, L-carnosine reduced the abundance of 4-HNE-modified proteins and blunted the expression of senescence biomarkers CDKN1A (p21 Cip1 ), PLAUR , BCL2L1 , and BCL2L2. Taken together, the results suggest that lipid enals are endogenous regulators of cellular senescence and that biogenic lipid-induced senescence (BLIS) may represent a mechanistic link between oxidative stress and age-dependent pathologies.

Stearoyl-CoA desaturase-1 (SCD1) is a critical enzyme involved in lipid metabolism that catalyzes the synthesis of saturated fatty acids into monounsaturated fatty acids (MUFA), primarily oleate (C18:1) and palmitoleate (C16:1), that are required for membrane fluidity. Absence of SCD1 promotes lipid saturation which is implicated in lipotoxicity. Our previous studies showed that SCD1 deficiency protects against obesity and fatty liver but promotes inflammation and endoplasmic reticulum stress. To delineate the long-term consequences of SCD1 deficiency on hepatic Fibrosis, we employed liver specific SCD1 (LKO) mice fed a high carbohydrate low fat diet for 20 weeks. All animal studies were conducted in accordance with the Institutional Animal Care and Use Committee guidelines at The University of Wisconsin-Madison. Histological analysis revealed that LKO mice developed extensive fibrosis with necroinflammation compared with LOX control counterparts. Further analysis revealed an increase in markers related to: fibrosis, such as Cluster of Differentiation 14 (Cd14), Keratin 8, and Type II (Krt8); cirrhosis, such as latent transforming growth factor beta binding protein 1 (Tgfβ-1), Type 1 collagen (Col1a1), Type 3 collagen (Col3a1), and Smooth muscle alpha-2 actin (Acta2). Since LKO mice are protected against obesity and fatty liver, our findings suggest a novel link between monounsaturated fatty acid insufficiency and cellular pathways leading to fibrosis and cirrhosis in the absence of steatosis. Funding by NIH.

Stearoyl–CoA desaturase (SCD) is a central lipogenic enzyme that catalyzes the synthesis of monounsaturated fatty acids (MUFA) primarily oleate (C18:1) and palmitoleate (C16:1) which are integral parts of triglycerides, membrane phospholipids, cholesterol esters, and wax esters. Mice models in which either SCD1 or SCD2 was deleted globally were protected against diet induced obesity. However, adipose-specific SCD1 deletion did not protect mice against obesity probably due to compensation by adipose SCD2. We set out to investigate whether a combined deletion of SCD1 and SCD2 protects against obesity. We therefore fed mice that had a combined deletion of adipose tissue specific of SCD1 and SCD2 (½ AKO) with either a high carbohydrate or high fat diet for ∼19 weeks. All animal studies were conducted in accordance with the Institutional Animal Care and Use Committee guidelines at The University of Wisconsin-Madison. Our results showed that ½ AKO mice were protected again adiposity as shown by lower weights of: epidydimal white adipose tissue (WAT), inguinal WAT and brown adipose tissue. Moreover, weekly body weight monitoring showed, the ½ AKO had lower body weights compared with their LOX control counterparts. These findings suggest that absence of SCD1 from the adipose tissue was compensated for by SCD2, and thus it requires a combined deletion of SCD1 and SCD2 in adipose tissue to protect against diet induced obesity. Funded by NIH.

Mitochondrial dysfunction is a prominent factor contributing to age-associated loss of muscle mass and force (a.k.a., sarcopenia). Yet, events preceding age-related mitochondrial dysfunction, which may allow the development of new therapies, remain poorly understood. Physical coupling of the outer mitochondrial membrane (OMM) to the endoplasmic or sarcoplasmic reticulum (ER), termed mitochondria ER contact sites (MERCs), modulate several mitochondrial processes influencing cellular function. In an energetically demanding and primarily post-mitotic tissue, we hypothesized that alterations in MERCs correlate with the development of sarcopenia. We also hypothesized that MERCs respond to exercise training and may contribute to beneficial muscular remodeling in older adults. To address these, we studied three age groups of male C57BL6N mice: young adults (Y, 5 mo. of age), old (O, 20 mo. of age), and very old (VO, 31 mo. of age). An additional group of old mice underwent 8-9 weeks of treadmill training (OET). Muscle mass and contractile function decreased with aging; VO animals displayed ~25% decline in maximum tetanic force vs. Y mice (p<0.0001). Fatigability (assessed via repetitive sub-maximal contractions) increased by ~10% with aging but was attenuated in the OET group (p<0.001). In saponin-permeabilized muscle fibers, aging did not affect mitochondrial oxidative capacity. However, H2O2 emission was nearly doubled in the O group (p<0.01) and this trend was partially alleviated by exercise training. Assessed via TEM, aging decreased the size of MERCs (i.e., length of SR and OMM apposition) by around 20% (p<0.01). Interestingly, OET animals displayed ~50% increase in MERC coverage (i.e., proportion of OMM covered by SR; p<0.0001). Immunoblots of cellular MERC fractions revealed that MERC proteins associated with calcium exchange were altered with age and exercise. The OMM channel, VDAC1, was reduced by 20% in O muscles (p=0.02), while Grp75, a tether protein, was ~25% higher in OET (p=0.02). Quantitative proteomic analyses revealed various MERC proteins being modified by aging and exercise. Our findings indicate that changes in MERC structure and protein composition may underlie early events preceding the development of sarcopenia and that exercise-mediated adaptations at MERCs may contribute to the beneficial adaptations in aging skeletal muscle. Supported by the University of Iowa Fraternal Order of Eagles Diabetes Research Center (UIowa FOEDRC). 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.

Obesity presents in about 90% of the diabetic patients, a risk factor that makes them more susceptible to cardiometabolic disorders, particularly insulin resistance and ultimately T2 diabetes. Increased oxidative stress and specifically lipid peroxidation are known to be major pathogenic factors driving these disorders in obesity. We recently reported that diabetic patients were found to have significantly lower level of glutathione peroxidase 4 (GPx4)- an antioxidant selenoenzyme which neutralizes lipid peroxides. Carnosine, a histidine-containing dipeptide which is highly concentrated in muscle and brain, has shown a remarkable therapeutic potential for preventing diabetes and its complications when administered orally in experimental and clinical studies of obesity. The extent to which carnosine can mitigate these disorders in the presence of GPx4 deficiency is not known however, and this is critical to determining its efficacy in diabetes patients. To address this question, wild-type (WT) and GPx4+/− male were randomly assigned to either standard chow (CNTL) or high fat high sucrose diet (HFHS) for 16 weeks. Seven weeks after starting the diet, half of the HFHS diet groups received 80 mM carnosine oral carnosine supplementation in their drinking water. Glucose and insulin tolerance tests performed 8 weeks after starting the diet revealed that carnosine significantly improved glucose tolerance in obese WT (P<0.05) but not obese GPx4+/− mice. Interestingly, carnosine treatment did significantly improve insulin sensitivity in the GPx4+/− mice, and to a lesser extent the WT mice. At the molecular level, we observed that HFHS diet up-regulated GPx4 protein in cardiac tissue from WT but not GPx4+/− mice, and protein oxidation was significantly reduced with carnosine treatment in both genotypes. Collectively, these findings indicate that carnosine supplementation could potentially mitigate insulin resistance even in patients with compromised antioxidant capacity (e.g., diabetes). Further analysis is in progress to evaluate the effectiveness of carnosine supplementation on additional cardiometabolic complications that are associated with diet induced obesity. 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.