bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevated blood pressure follows physiological body-water conservation
Authors: Marton Adriana , Rauh Manfred , Takase-Minegishi Kaoru , Saffari Seyed Ehsan , Lim Tzy Tiing , Wild Johannes , Nagel Armin 
Published: May 2024

Background: Pre-clinical evidence suggests that blood pressure (BP) increase is part of an adaptive physiological body response designed to prevent under-hydration. This idea challenges established thinking that hypertension is caused by initial salt-driven over-hydration. We tested the hypothesis that this alternative view also holds true in humans. Methods: In a mechanistic study, we investigated the interrelation between daily Na+ and water intake, renal solute and water excretion, renal water conservation, and body Na+ balance with BP in 6 healthy men living in a controlled environment for 205 days. In an additional daily-life observational study we investigated the interrelation between BP and adaptive-physiological water and Na+ conservation in 108 Singaporeans. Results: In participants living under controlled conditions, BP increased when urine osmolality was high, and fluid intake or urine volume was low. This BP-increasing water conservation response was not caused by body Na+ retention. Similarly, participants living under daily-life conditions showed a BP-elevating adaptive body water conservation response with increased plasma solute concentration, increased plasma vasopressin levels, and reduced urine volume production due to reduced renal free-water excretion. Participants with higher BP relied on more urea and glucose solutes, but on less Na+ solutes, to maintain their hydration status. Participants with essential hypertension showed more pronounced adaptive-physiological water conservation. None of these hypertension-specific water conservation responses were accompanied by differences in 24-h Na+ excretion. Conclusions: BP increase in humans is part of a systemic body water conservation response that occurs largely independent of body Na+ balance. The Mars500 Salt and Water Homeostasis Project was realized by grant support from the German Federal Ministry for Economics and Technology/DLR Forschung unter Weltraumbedingungen (50WB1624-50WB2024) and the Interdisciplinary Centre for Clinical Research (IZKF Junior Research Group 2), Friedrich-Alexander-University of Erlangen-Nuremberg to JT. The food products were donated by APETITO, Coppenrath und Wiese, ENERVIT, HIPP, Katadyn, Kellogg, Molda, and Unilever. The Sodium Storage in Singaporeans Project was realized with grant support from Duke NUS Medical School (Duke-NUS-KBrFA/2019/0026) to JT. 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.
A Mitochondrial Targeted Ubiquinol (MitoQ) Improves Immune Cell Bioenergetics in Patients with Heart Failure with Preserved Ejection Fraction
Authors: Bohmke Natalie , Chavez Domenico , Abbate Antonio , Markley Roshanak , Carbone Salvatore , Kirkman Danielle 
Published: May 2024

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a proinflammatory syndrome. Mitochondrial dysfunction that is characteristic of HFpEF could alter immunometabolism, attenuating the functional reserve of immune cells. In addition, immune cell mitochondrial respiration is a biomarker of systemic mitochondrial health. The aim of this study was to assess the impact of a chronic oral mitochondrial targeted ubiquinol (MitoQ) on the immune cell bioenergetic profile in patients with HFpEF. We hypothesized that MitoQ administration in patients with HFpEF, would improve mitochondrial respiration in peripheral blood mononuclear cells (PBMC’s). METHODS: In this double-blind, crossover trial 8 patients with a clinical diagnosis of HFpEF (6 female, 2 male; 6 African American/Black, 2 white; mean ± SEM, Age, 58±5 years; BMI, 37±1 kg/m2) received a 4 week oral dose of MitoQ (MTQ, 20 mg/day) and placebo (PLB) in random order separated by a 2 week wash out period. Following completion of each trial arm, a venous blood sample was obtained and PBMCs were isolated using density gradient centrifugation. High resolution respirometry coupled with modulators of cellular respiration was performed to obtain basal respiration, ATP-linked respiration, maximal respiration, and spare respiratory capacity of the immune cells. Paired samples t-tests were used to compare variables between conditions. RESULTS: MitoQ was safe, well tolerated, and compliance was high (MTQ, 99 ± 1%; PLB, 89±4%). Basal respiration (MTQ, 106.4 ± 11.5 pmol/min; PLB, 66.5±5.9 pmol/min; p=0.002), ATP-linked respiration (MTQ, 41.4± 16.9 pmol/min; PLB, 16.3±6.7 pmol/min; p=0.04), maximal respiration (MTQ, 323.9 ± 50.0 pmol/min; PLB, 65.4±23.1 pmol/min; p=0.01), spare respiratory capacity (MTQ, 217.5 ± 39.6 pmol/min; PLB, 149.6 ±18.2 pmol/min; p=0.02), were higher following MTQ compared to PLB. CONCLUSIONS: In patients with HFpEF, administration of a mitochondrial targeted ubiquinol improved the immune cell mitochondrial respiration capacity and effciency. An increase in spare respiratory capacity following MTQ reflects an improvement in functional reserve that would augment the ability to respond to an acute stressor. These findings have positive implications for the ability to target and improve mitochondrial function in patients with HFpEF. Future work should investigate if the observed improvements in immune cell mitochondrial function are mirrored in other tissues. Supported by AHA 19CDA3474002. 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.
BDNF/TrkB Induces pCREBS133 Phosphorylation and Activates Mitochondrial Biogenesis in Rat Phrenic Motor Neurons
Authors: Davis Anne , Dasgupta Debanjali , Fogarty Matthew , Mantilla Carlos B. , Sieck Gary 
Published: May 2024

Neural control of the diaphragm muscle (DIAm) is essential to sustain breathing. During breathing, fatigue resistant DIAm motor units are recruited comprising smaller phrenic motor neurons (PhMNs) and type I and IIa muscle fibers. Larger PhMNs comprise more fatigable DIAm motor units that are infrequently active during expulsive behaviors. The difference in activation history is reflected in the higher mitochondrial volume density in smaller PhMNs. In PhMNs, brain-derived neurotrophic factor (BDNF) signals through its high-affnity receptor, tropomyosin receptor kinase B (TrkB.FL). Previously, we found that intrathecal BDNF treatment induces CREB phosphorylation at Serine 133 (pCREBs133). We hypothesized that pCREBs133 binds to the PGC1a promoter, transcriptionally targeting PGC1a expression, mediating downstream increased expression of NRF1, NRF2, and TFAM and mitochondrial biogenesis. To test this hypothesis, we used a chemosensitive TrkBF616 rat model with a knock-in allele sensitive to 1NMPP1 in that TrkB kinase is inhibited following 1NMPP1, a small molecule derivative of the protein kinase inhibitor protein phosphatase 1 that plays a significant role inhibiting the TrkB phosphorylation and activation. Systemic treatment of 1NMPP1 in TrkBF616 rats inhibits TrkB kinase activity. A bioinformatic analysis was performed to identify a putative binding site for pCREBs133 in the PGC1a promoter sequence in rats. Using a chromatin immunoprecipitation (ChIP) assay we found that pCREBS133 binds to the PGC1a promoter in rat cervical ventral horn. We showed that intrathecal BDNF treatment increased pCREBs133 phosphorylation, which was blocked by 1NMPP1 treatment in TrkBF616 rats. PGC1a, NRF1/2, and TFAM protein was compared in cervical ventral horn lysates from BDNF- and BDNF+1NMPP1-treated TrkBF616 rats by qRT-PCR and Western Blot. Relative mtDNA copy number (normalized to nuclear DNA) was quantified by qPCR to assess the mitochondrial biogenesis. All results were analyzed by paired t-test. Following 1NMPP1-induced inhibition of TrkB kinase, PGC1a, NRF1/2, and TFAM mRNA and protein expression was reduced. Consistent with these findings, mtDNA copy number was decreased following TrkB kinase inhibition by 1NMPP1. We conclude that inhibition of TrkB kinase by 1NMPP1 reduces PGC1a-mediated mitochondrial biogenesis in rat cervical ventral horn. Supported by NIH grants AG44615 and HL146114. 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.
Metabolomic and transcriptomic correlative analyses in germ free mice link probiotic-associated metabolites to host intestinal fatty acid metabolism and b-oxidation
Authors: Ambat Jayanth , Antonio Jayson , Bala Ajitha , Suntornsaratoon Panan , Flores Juan , Li Wei Vivian , Jones Abby 
Published: May 2024

While a transcriptomics-led examination of the effects of probiotics offers valuable insights into their influence on host gene regulation, the dynamic interactions between host metabolism and probiotics require an integrated analysis and multiomics approach to provide deeper insight into the underlying molecular mechanisms governing these associations. Here, we developed a high throughput bioinformatic tool ‘metabolome-transcriptome correlation analysis’ (METRCA, in press) that can determine whether a certain gene-metabolite association is up or downregulated and predict whether a metabolite’s or gene’s tissue location impacts its interaction with one another. To test this, we analyzed by LCMS and bulk-RNA sequencing then assessed linkages between serum as well as fecal metabolites and disease- or metabolism-associated genes in the ileum of gnotobiotic mice fed either a tryptophan (trp)-deficient or -suffcient diet then mono-associated with Lactobacillus rhamnosus GG (LGG) or administered PBS (control). We discovered significant associations, mainly in LGG mice fed trp, between metabolites and ileal genes involved in fatty acid metabolism (FAM) and oxidation (FAO). This association was specific and not observed in GF mice gavaged with PBS, monocolonized with R. gnavus, or fed trp- diets, and in SPF mice. Many fecal trp metabolites like indole-3-acetamide and serum trp metabolites like indole acetonitrile were significantly, positively correlated with important intestinal FAM genes Dgat1 and Mgat2. Likewise, numerous fecal metabolites like 5-hydroytrp and several serum trp metabolites like serotonin emerged as positively correlated metabolites with the rate-limiting FAO genes Acaa2 and Cpt2. Serum indoles were more strongly associated with both FAM and FAO genes than fecal indoles. Few fecal and serum metabolites were found negatively correlated with FAM and FAO genes. Since most are positive correlators, these findings suggest a testable hypothesis that LGG- and trp-dependent metabolites increase the intestinal metabolism of dietary lipids, providing a mechanism to previous findings that LGG supplementation in mice protected against diet-induced obesity and fatty liver disease. Analytical approaches like METRCA can thus be used to extract valuable information from metabolite and RNA-Seq datasets, generating novel hypotheses that may discover new interactions between microbe- or nutrient-associated metabolites and host metabolic or disease-related pathways. NIHR01-AT010243 (NG,RF), R01DK119198 (NG), NSF 1754783 (RF)). 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.
A conserved interaction between the GRIP and finger domains in ENaC subunit is critical for proteolytic activation
Authors: Wang Xue-Ping , Humeda Sami , Kashlan Ossama 
Published: May 2024

The epithelial sodium channel (ENaC) mediates Na+ transport in several epithelia, including the lung and the aldosterone-sensitive distal nephron. ENaC is a heterotrimer comprising ⍺βγ or δβγ subunits. Though sharing similar structural folds as other ENaC/Degenerin family members, ENaC subunits have a unique extracellular GRIP (Gating Release of Inhibition by Proteolysis) domain, and the a and g subunits have polybasic sites that can be cleaved by proteases. Aldosterone promotes double cleavage of the α and γ subunits at these sites, leading to release of the first two b-strands of the GRIP domain (P1 and P2) and channel activation. Structural and sequence conservation suggest that the interaction between P1 and the channel are mediated by a Pro-Leu motif in P1 and a conserved Trp residue in helix α2 of the finger domain. We hypothesized that this interaction is critical for the inhibitory properties of the imbedded tract, defined by P1, and thus channel activation upon release. To test our hypothesis, we substituted the conserved Trp with Ala or Phe in each of the human ENaC subunits and performed two-electrode voltage clamp experiments in Xenopus oocytes to measure the effects on function. Compared to wild type channels, we found that ⍺W251F, βW218A, βW218F, γW229F, and δW396F had no effect on amiloride-sensitive currents. Interestingly, δW396A decreased amiloride-sensitive current by 20% (p=0.01). However, amiloride-sensitive currents were greatly enhanced for Ala mutations in subunits subject to cleavage: ⍺W251A (p=0.02) and γW229A (p=0.01). In line with channel activation, ⍺W251A weakened sensitivity to extracellular Na+ (Na+ self-inhibition), and γW229A completely lost its sensitivity to both extracellular Na+ and chymotrypsin. We also tested the effect of inhibitory peptides (α8 and γ11) corresponding to the imbedded inhibitory tracts (i.e., P1 of the GRIP domain) of the ⍺ and γ subunits. ⍺W251A was insensitive to 10 μM ⍺8 compared to wild type ENaC (85% inhibition), and γW229A was insensitive to 100 μM γ11 compared to wild type ENaC (40% inhibition). Collectively, our results provide evidence for the idea that the interaction between the Pro-Leu motif in GRIP domain’s P1 β-strand and the conserved Trp in the finger domain’s α2 helix is critical for the autoinhibitory properties of P1, and therefore activation upon P1 release after proteolysis of the ⍺ and γ subunits. R01 DK125439 Kashlan (PI) ENaC Regulation by Biliary Factors. 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.
Resting Beat-to-Beat Blood Pressure Variability in Young, Healthy, Non-Hispanic Black Females
Authors: Taherzadeh Ziba , Young Benjamin , Skow Rachel , Stephens Brandi , Fadel Paul 
Published: May 2024

Background: Non-Hispanic Black (BL) individuals are at greater risk for cardiovascular disease and hypertension compared to other racial groups. Beat-to-beat blood pressure variability (BPV) is a known predictor of adverse cardiovascular outcomes. Our laboratory recently reported an augmented resting beat-to-beat BPV in non-Hispanic BL males compared to their White (WH) male counterparts. However, racial differences in beat-to-beat BPV between non-Hispanic BL and non-Hispanic WH females are unknown. Therefore, we tested the hypothesis that young, healthy, non-Hispanic BL females have elevated resting beat-to-beat BPV compared to healthy age and body mass index matched WH females. Methods: We studied 12 young healthy non-Hispanic BL females (20 ± 2 years, 25.2 ± 4 kg/m2, mean ± standard deviation) and 12 young healthy non-Hispanic WH females (22 ± 3 years, 22.7 ± 3 kg/m2; P = 0.13 and P = 0.10, respectively). Beat-to-beat arterial blood pressure (finger photoplethysmography) was continuously recorded during ten minutes of supine rest. Mean, standard deviation (SD), range, coeffcient of variation, and average real variability (ARV) were calculated for systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Results: Resting absolute SBP (BL: 113 ± 12 mmHg; WH: 112 ± 7 mmHg; P = 0.98), DBP (BL: 69 ± 7 mmHg; WH: 66 ± 5 mmHg; P = 0.22), and MAP (BL: 83 ± 7 mmHg; WH: 81 ± 4 mmHg; P = 0.48) were not different between groups. Likewise, beat-to-beat SBP SD (BL: 3.5 ± 0.78 mmHg; WH: 4.0 ± 1.16 mmHg; P = 0.21), range (BL: 21 ± 5 mmHg; WH: 24 ± 6 mmHg; P = 0.26), coeffcient of variation (BL: 3.01 ± 0.82%; WH: 3.56 ± 0.96%; P = 0.20), and ARV (BL: 2.02 ± 0.46; WH: 2.26 ± 0.6; P = 0.27) were not different between BL and WH females. There were also no differences in any of the beat-to-beat BPV measures for DBP or MAP between BL and WH females (all P > 0.05). Conclusion: In contrast to our hypothesis and previous work in non-Hispanic BL males, these preliminary data suggest that beat-to-beat BPV is not different between non-Hispanic BL and WH females. This work was supported by the College of Nursing and Health Innovation. 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.
Examining The Effects Of Gallein On Opioid Induced GIRK Currents
Authors: Keldsen Charles , Beeman Carley , Bartol Kai , Levitt Erica , Smrcka Alan 
Published: May 2024

Opioids are powerful analgesics, but carry a risk of overdose that has become a pressing issue to public health in the United States. Overdose deaths are caused by the opioid-induced shutdown of neuronal circuits that operate unconscious breathing cycles, leading to respiratory depression. Respiratory depression, alongside antinociception, is mediated by the activation of μ-opioid receptors, which are coupled to inhibitory heterotrimeric G proteins. Recent studies have shown that gallein, a Gβγ subunit inhibitor, amplifies the antinociceptive effects of opioids through Gq-phospholipase C (PLC) mediated mechanisms, while either attenuating or having no effect on respiratory depression. The molecular mechanisms of gallein effects on respiratory depression are unclear. Based on the binding interface, gallein is predicted to inhibit Gβγ binding to phospholipase C, but not G protein inwardly rectifying potassium channels (GIRK). The goal of this study is to examine the effects of gallein on opioid-induced GIRK currents, with or without Gq subunit activation, in mouse locus coeruleus (LC) neurons. The LC is an area of particular interest due its involvement in respiratory circuits, and activation of Gq-coupled pathways decreases the amplitude of opioid-mediated GIRK currents in LC neurons. We hypothesized that gallein would have no effect on opioid mediated GIRK currents without Gq activation, but would prevent Gq-mediated inhibition of GIRK. We tested this hypothesis using whole-cell voltage-clamp recordings of LC neurons contained in brain slices from adult male and female mice. The endogenous opioid agonist Met-enkephalin induced outward GIRK currents that were not significantly altered by gallein. The Gq-coupled receptor agonist oxotremorine-M reduced the amplitude of Met-enkephalin mediated GIRK currents, as expected. Preliminary data suggests no effect of gallein on GIRK currents in the presence of Gq activation, contrary to our hypothesis. These results will increase our understanding of the role of PLC in Gq-mediated inhibition of GIRK currents at the cellular level and provide insight regarding the potential respiratory related impacts associated with using gallein derived compounds in combination with opioids to increase opioid antinociception and reduce the doses of opioids needed to treat pain. This research is supported by NIH Grant R01DA047978-05 to ESL. 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.
An Ex Vivo Approach to Studying Renin Dynamics
Authors: Vanden Avond Mark , Grzybowski Michael , Greene Andrew , Liang Mingyu , Cowley, Jr Allen , Geurts Aron 
Published: May 2024

Hypertension is the leading risk factor for cardiovascular disease and impacts one in three adults globally. One non-coding mechanism that may affect blood pressure regulation and alter hypertension risk in the general population is the disruption of chromatin conformation. CCCTCF-binding factor (CTCF) has many important functions including regulating the conformation of chromatin by binding to specific DNA sequences. Renin has multiple CTCF motifs surrounding the gene and cellular expression of CTCF is critical for proper Renin expression. Using CRISPR-Cas9 in the Dahl salt-sensitive (SS) rat, we have developed three mutant rat models with one or more mutations to the CTCF motif surrounding the Renin gene. CTCF binding was confirmed to be disrupted in all three models at the CRISPR-targeted locations. Plasma renin activity (PRA) was measured in wild-type (WT) and mutant rats fed a 0.1%, 0.4% or 4.0% NaCl diet for four days. PRA in WT males responded as expected to dietary NaCl (17.52±0.81, 12.87±1.00, and 7.13±0.19 ng/mL; p<0.05 for 0.1% and 4.0% vs. 0.4%). Interestingly, two of our male mutant models failed to increase their PRA on the 0.1% NaCl diet (CTCF1=13.87±0.86; CTCF2=13.95±0.59; p<0.05 compared to WT 0.1% NaCl). Despite this, no differences in Renin mRNA were detected. We hypothesize Renin transcriptional response to salt depletion is delayed in the mutant models compared to WT. To test this, we developed an ex vivo approach to culture kidney slices and evaluate Renin expression to a variety of stimuli. Kidneys from SS rats fed low salt (LS; 0.4% NaCl) or high salt (HS) diet (4.0% NaCl) for 24 hours were harvested, sliced, and cultured in basal media or media containing increasing salt. Renin expression was examined at 1, 2, 4, 8 and 24 hrs of incubation. Kidney slices from SS rats fed HS that were incubated basal media stimulated Renin expression as soon as 2 hrs and continued to increase until 8 hrs. This was the first time for establishing an ex vivo approach for motoring the dynamic changes in Renin expression in response to a stimulus by culturing kidney slices. This method could be used to evaluate other stimuli, such as therapeutics, and could decrease the number of animals needed for a study. Funded by NIH 1HL149620. 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.