bluuebunny/crossref_metadata_2025_split huggingface dataset:
Muscle pump‐induced inhibition of sympathetic vasomotor outflow during leg cycling is blunted by high‐intensity muscle metaboreflex activation
Authors: Katayama Keisho , Barbosa Thales C. , Kaur Jasdeep , Young Benjamin E. , Shigehiko Ogoh , Fadel Paul J. 
Published: June 2021

Muscle sympathetic nerve activity (MSNA) decreases during leg cycling at light or mild intensity (below 40%VO2max), and this is attributed to loading of the cardiopulmonary baroreceptors via muscle pump‐induced increases in venous return. In contrast, MSNA increases during leg cycling above moderate intensity, suggesting that the sympathoinhibitory effect of the cardiopulmonary baroreflex could be overridden by a powerful sympathoexcitatory drive. Skeletal muscle metaboreflex is known to elicit robust sympathoexcitation. Therefore, we tested the hypothesis that high‐intensity muscle metaboreflex activation attenuates muscle pumpinduced cardiopulmonary baroreflex‐mediated inhibition of MSNA during leg cycling. In five healthy young men (25 ± 2 yrs, mean ± SE), MSNA (radial nerve) and thoracic impedance were recorded. Subjects performed cycling at 30 watts with and without muscle metaboreflex activation. Graded isolation of the muscle metaboreflex was achieved by post‐exercise ischemia (PEI) following low and high intensity isometric handgrip at 20% (PEI‐L) and 40% (PEI‐H) maximum voluntary contraction, before the onset of leg cycling. Resting MSNA burst frequency was 23.4 ± 0.4 burst·min−1 and MSNA total activity was 1503 ± 20 AU·min−1. As expected, leg cycling alone significantly decreased MSNA burst frequency and total activity (Δtotal activity: −43.0 ± 4.9%, P < 0.05). When leg cycling was performed during muscle metaboreflex activation with PEI, MSNA burst frequency and total activity decreased significantly during PEI‐L (Δtotal activity: −32.8 ± 7.1%, P < 0.05), but not during PEI‐H (Δtotal activity: +1.6 ± 7.1%, P = 0.89). Thoracic admittance, which was calculated from thoracic impedance as an index of central blood volume, was not changed during handgrip or PEI, whereas leg cycling evoked similar increases in thoracic admittance during all conditions (ΔLeg cycling alone: +3.5 ± 1.0, ΔPEI‐L: +3.6 ± 1.0, ΔPEI‐H: +3.6 ± 0.8 S·10−4, one‐way repeated measures ANOVA: F = 0.02, P = 0.98). These preliminary findings suggest that high intensity muscle metaboreflex activation attenuates muscle pump‐induced cardiopulmonary baroreflex inhibition of sympathetic vasomotor outflow during dynamic leg cycling.Support or Funding InformationJSPS KAKENHI Grant Number JP16KK0201, UTA College of Nursing and Health InnovationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The intercalated cell MR directly regulates pendrin abundance, subcellular distribution and function
Authors: Pham Truyen Derek , Verlander Jill W , Wang Yanhua , Lazo‐Fernandez Yoskaly , Chen Chao , Wall Susan M 
Published: June 2021

Aldosterone increases pendrin‐dependent Cl− absorption and HCO3− secretion and activates the intercalated cell (IC) mineralocorticoid receptor (MR) in type B (ICs). Whether the IC MR modulates CCD function and whether aldosterone acts directly on the IC MR in vivo to regulate pendrin in vivo remains to be determined. The purpose of this study was to determine the effect of the IC MR on pendrin abundance, subcellular distribution and function in vivo and to determine if this was from a direct effect of the IC MR. To answer these questions, we developed mice in which MR gene ablation occurred specifically within ICs and measured Cl− absorption in cortical collecting ducts perfused in vitro, pendrin total protein abundance and pendrin subcellular distribution in these IC MR null mice and their wild type littermates. Cl− absorption was ~50% lower in cortical collecting ducts from aldosterone‐treated IC MR null relative to wild type mice. Moreover, following dietary NaCl restriction or an aldosterone infusion, pendrin total protein abundance and pendrin's relative abundance in the apical plasma membrane region were lower in the IC MR null than in wild type littermates. We asked if IC MR gene ablation modulates pendrin abundance and function through a direct effect of the MR within ICs. Since IC MR null mice express both MR positive and negative ICs, we compared pendrin label intensity and pendrin subcellular distribution in MR positive and negative ICs from the same IC MR KO mouse. We observed that pendrin label intensity and pendrin's relative abundance in the apical plasma membrane region were much lower in MR negative than MR positive ICs that were taken from aldosterone‐treated or NaCl‐restricted IC MR null mice. In conclusion, IC MR gene ablation reduces Cl− absorption in the CCD. Furthermore, IC MR gene ablation reduces pendrin total protein abundance and pendrin abundance in the region of the apical plasma membrane through a direct effect of the MR within ICs.Support or Funding InformationSusan M. Wall, M.D.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Palm Domain Hydrophobic Residues and ENaC Gating
Authors: Wang Xueqi , Chen Jiingxin , Kleyman Thomas R. , Sheng Shaohu 
Published: June 2021

Epithelial Na+ channel (ENaC) gating is allosterically modulated by both its extracellular and intracellular domains. Among several regions that have been implicated in regulating ENaC gating are the extracellular palm domains where three subunits interface. We previously identified a palm domain hydrophobic residue (γL511) as an important determinant of ENaC gating. Interestingly, its homologous residue in chicken ASIC1a (L414), located at the β11 and β12 linker, reportedly adapts flipped conformations in the rest (or open) and desensitized states. In this study, we investigated the roles of γL511 homologous resides in the α and β subunits (αL531 and βF502) in regulating ENaC gating, by mutating these residues to a hydrophilic glutamine and examining channel properties in Xenopus oocytes. ENaCs both transport Na+ and are inhibited by extracellular Na+, a response referred to as Na+ self‐inhibition that reflects a reduction in channel open probability and is often used as a surrogate for ENaC gating. Similar to γL511Q, both αL531Q and βF502Q significantly reduced the magnitude and speed of the Na+ self‐inhibition response (p<0.01 vs WT, n=6). Oocytes expressing αL531Qbg ENaCs also showed significantly greater amiloride‐sensitive currents (relative‐to‐WT currents: 1.9 ± 0.2, Mean ± SE, p<0.001, n=32). However, βF502Q expressing oocytes showed the channel currents that were similar to wild type (relative‐to‐WT currents: 0.9 ± 0.1, p>0.05, n=22). The changes caused by both αL531Q and βF502Q on the channel activity and Na+ self‐inhibition response appear to be less dramatic than the previously reported γL511Q. Our results suggest that the highly conserved palm domain hydrophobic residues in three subunits have similar roles in regulating ENaC gating.Support or Funding InformationDK079307 DK051391This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Paracrine Communication Links Sodium Chloride Cotransporter Activity in the Distal Convoluted Tubule to Remodeling of the Aldosterone‐Sensitive Distal Nephron
Authors: Zapf Ava , Grimm PR , Delpire Eric , Welling Paul A 
Published: June 2021

We recently discovered that cell‐specific expression of constitutively active SPAK (CA‐SPAK) in the early distal tubule is sufficient to drive a remodeling process of the entire distal nephron that includes structural dystrophy of the aldosterone‐sensitive distal nephron and inhibition of ROMK and ENaC (Grimm et al, JASN ’17). Here, we tested the hypothesis that SPAK‐activation of NCC stimulates the release of paracrine or autocrine factors that cause the dystrophic response in the CNT.We found increased levels of PGE2 in kidney cortical homogenates of CA‐SPAK mice compared to control mice. Comparable elevation of PGE2 was also observed when NCC was physiologically activated by feeding wild‐type mice (WT) a low potassium diet (LKD). Administration of the NCC‐blocking diuretic, hydrochlorothiazide, to either CA‐SPAK or WT mice on LKD, restored PGE2 to control levels, but had no effect on PGE2 of WT or SPAK KO mice. Thus, PGE2 is elevated in response to super activation of NCC.PGE2 synthesis is mediated by prostaglandin E synthase isoforms. As revealed in western blot analysis, the microsomal prostaglandin E synthase‐1(mPGES1) was elevated in the kidney cortex of CA‐SPAK mice and WT mice on LKD compared to control mice. Quantitative microscopy of mPGES1 surprisingly revealed the augmentation of mPGES1 was confined to the CNT and CCD of CA‐SPAK and LKD treated mice. No changes in mPGES1 were observed in the DCT1.In conclusion, these studies identify PGE2 as a potential remodeling autocrine that is released from the CNT and CCD in response to activation of NCC. We speculate that decreased sodium delivery to the CNT and CCD when NCC is activated drives the response, similar to the mechanism by which PGE2 synthesis is stimulated in the macula densa with changes in sodium reabsorption in upstream tubule segments. The autocrine pathway provides a novel means to communicate potassium sensing in the DCT to potassium secretion in the ASDN.Support or Funding InformationSupported by the NIDDK and Fondation LeducqThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Inhibition of basolateral ClC‐K2 chloride channels in collecting duct intercalated cells by adenosine
Authors: Zaika Oleg , Tomilin Viktor , Pochynyuk Oleh 
Published: June 2021

Adenosine plays an important role in various aspects of kidney physiology, including vasoconstriction of afferent arterioles, modulation of renin secretion and tubule‐glomerular feedback. In addition, adenosine regulates water‐electrolyte transport in the renal tubule, while specific targets are less defined. The collecting duct has the highest expression of adenosine receptors, particularly A1R. Interstitial adenosine levels are greatly increased up to a micromolar range in response to dietary salt loading, favoring activation of its receptors and respective end‐effectors on the basolateral side. The collecting duct is composed of electrically uncoupled principal and intercalated cells having different morphology and physiological roles. We previously showed that the basolateral membrane of principal cells has primarily potassium conductance mediated by Kir4.1/5.1 (KCNJ10/16) channels to mediate K+ recycling and to set up a favorable driving force for Na+/K+ exchange. Intercalated cells lack electrogenic K+ flux but express chloride ClC‐K2 channel mediating transcellular Cl− reabsorption in the collecting duct. Using patch clamp electrophysiology in freshly isolated mouse collecting ducts, we found that acute application of adenosine reversely inhibits ClC‐K2 open probability from 0.31±0.04 to 0.17±0.06 and to 0.10±0.05 for 1 μM and 10 μM, respectively. Inhibitory effect of adenosine was abolished in the presence of A1R blocker, DPCPX (10 μM) suggesting the central role of these receptors in mediating adenosine actions. Consistently, application of A1R agonist N6‐cyclohexyladenosine (CHA, 1 μM) recapitulated the inhibitory action of adenosine on ClC‐K2 open probability. In contrast, adenosine (10 μM) had no measureable effect on Kir4.1/5.1 channel activity in principal cells of the collecting duct. Overall, we demonstrate that adenosine selectively inhibits ClC‐K2 activity in intercalated cells by targeting A1R receptors. We propose that inhibition of transcellular Cl− reabsorption in the collecting duct by adenosine would aid to augment NaCl excretion during high salt intake.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
LTP Nanoparticles Seeded with Plasmid for Vascular Endothelial Growth Factor Receptor 2 Improve Fetal Morphometrics in a Rat Model of Preeclampsia
Authors: Balser Brtittany A , Novak Jacqueline , Yun Yang H , Kisha Annika F , Ramirez Rolando JJ 
Published: June 2021

Recent studies by our lab have demonstrated that the delivery of L‐Tyrosine Phosphate nanoparticles seeded with plasmid for Vascular Endothelial Growth Factor Receptor 2 (LTP VEGFR2) normalizes mean arterial pressure, uterine vessel myogenic reactivity, and fetal growth restriction in the reduced uterine perfusion pressure (RUPP) animal model. The goal of this study was to investigate fetal morphometrics in RUPP+LTP VEGFR2 dams. For the RUPP procedure, silver clips are placed on the abdominal aorta (0.2mm i.d.) below the kidneys and the utero‐ovarian arteries (0.1mm i.d.) on day 14 of pregnancy in Sprague‐Dawley rats. SHAM pregnant rats undergo the same surgery without the clip placement. On the same day as surgery, LTP nanoparticles encapsulated with plasmid DNA encoding for VEGF Receptor 2 (VEGFR2), or nonsense were injected into the uterine wall. On day 21 of gestation, the uterus was removed and fetal weights, placental weights, and head circumference were recorded on three fetuses from each dam. The fetuses were selected based on position in the uterus in relation to the site of injection of the LTP nanoparticles. Fetal position was designated as the following: Site 1 was selected as the closest to the injection site, Site 6 was distal in the same uterine horn, and Site 14 was contralateral to Site 6. Fetal weight for pups at Site 1 was significantly increased in RUPP rats treated with VEGFR2 nanoparticles compared to RUPP treated with nonsense nanoparticles (4.70g ± 0.44 vs. 3.89g ± 0.31; p<0.05). Placental weight at Site 1 was significantly increased in RUPP rats treated with VEGFR2 nanoparticles compared to RUPP treated with nonsense nanoparticles (0.635g ± 0.06 vs. 0.491g ± 0.04; p<0.05). Head circumference was also significantly increased in pups at site 1 in RUPP rats treated with VEGFR2 nanoparticles as compared RUPP rats treated with nonsense nanoparticles (2.37cm ± 0.32 vs. 1.45cm ± 0.07; p<0.05). There were no significant differences in fetal weights, placental weights and head circumference in the SHAM group at any of the fetal positions. Furthermore, there were no significant differences when comparing between the SHAM and RUPP groups. The fetal measurements (fetal weight, placental weight and fetal head circumference) from RUPP treated with nonsense nanoparticles tended to be lower compared to the other groups (SHAM treated with VEGFR2 nanoparticles, SHAM treated with nonsense nanoparticles or RUPP treated with VEGFR2 nanoparticles; however, it failed to reach significance in this preliminary study. In conclusion, uterine injection of LTP nanoparticles with plasmid DNA encoding for VEGFR2 improved fetal morphometrics in RUPP animals.Support or Funding InformationAmerican Heart Association‐18AIREA3396032This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Activating the MasR/Ang1‐7 Pathway Reduces Muscle Atrophy and Function Loss Following Denervation
Authors: Albadrani Hind , Renaud Jean‐Marc 
Published: June 2021

Muscle atrophy is defined as a decrease in muscle mass that eventually leads to partial or complete muscle wasting. Muscle atrophy occurs in a variety of conditions including chronic diseases such as heart failure, limb immobilization and following a complete loss of muscle activity after spinal cord injury (SCI) and peripheral nerve injury. A consequence of muscle atrophy is large force decrease associated with muscle mass loss as well as contractile components. As a result of the force loss, atrophy decreases quality of life as the patient becomes unable to perform certain tasks as well as worsens the risk of accident while performing those tasks. Preventing the atrophy following peripheral nerve injury and thus muscle denervation will improve muscle physiology, especially, when a long time is necessary for nerve regeneration to be completed. Recent studies have provided evidence that activation of the MasR/Ang1‐7 signaling pathway reverses muscle atrophy induced by Ang II in chronic disease and immobilization. The objective of this study was to determine whether Ang 1‐7 also reduces the atrophy process and force loss following muscle denervation. Mouse extensor digitorum longus (EDL) and soleus were denervated by removing 3–4 mm of the sciatic nerve at the thigh level. Denervated mice were then divided into 4 groups: i) denervated; ii) denervated and treated with Ang 1‐7 (osmotic pump 100 ng/kg body weight/min); iii) denervated and treated with diminazene aceturate (DIZE, oral gavage 15 mg/day/kg body weight), a ACE2 activator, to locally increase Ang 1‐7 levels, and iv) denervated and receiving sucrose (oral gavage 1 mg/day/kg body weight). A 5th group of mice was used as control group, i.e., normal innervated muscle. The results show that Ang 1‐7 partially prevented muscle mass loss while fully preventing a loss of normalized force to CSA up to 4 week denervation period. The maintenance of the normalized maximum force by Ang 1‐7 suggests that muscle integrity, i.e., t‐tubules, sarcoplasmic reticulum (SR), and sarcomere, and functionality, i.e., membrane excitability, Ca2+ release and force, are better maintained. This study is thus providing evidence that Ang 1, 7 has therapeutic potential to prevent function loss following a denervation.Support or Funding InformationThis study was supported by the National Science and Engineering Research Council of Canada (NSERC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effects of Hypothermia on Skeletal Muscle Contractile Function: Comparison between Hibernators and Non‐hibernators
Authors: Krishnan Jishnu K S , Hunstiger Moriah , Rogers Jace , Oliver Scott Ryan 
Published: June 2021

The primary function of skeletal muscle (SKM) is to implement locomotion, but muscles also serve other important functions such as generating heat through shivering (and non‐shivering), which involves continuous contraction and relaxation. Arctic ground squirrels (AGS), Spermophilus parryii, undergo extreme temperature fluctuations during the hibernating season (body temperature as low as −3 °C), where they mostly remain physically inactive. Despite prolonged periods of immobilization and starvation during hibernation, AGS and other hibernating mammals are protected from muscle atrophy, weakness, and loss of protein content. In contrast, non‐hibernators (like Sprague Dawley (SD)) are susceptible to muscle atrophy, rhabdomyolysis and myotonia etc. due to muscle inactivity. To our knowledge no study has shown the effects of temperature on muscle contractile function compared between hibernators and non‐hibernators. We hypothesized that hibernators maintain their muscle contractile function and performance, over a wider temperature range compared to non‐hibernators. We characterized and compared the alterations in SKM contractile function during hypothermic temperature stress. An Ex vivo functional assay was implemented, utilizing a tissue organ bath system (TOBS) and involved extracting diaphragm muscle from both AGS and SD, create strips made from SKM while keeping it in oxygenated Ringers solution. Following transfer of strips to respective organ bath chambers, muscles were exposed to 37°C for 30 mins (control/initial phase), 30 mins of experimental temperature (4 °C; 15 °C; 25 °C and 37 °C), and then finally back to 37 °C for 30min (recovery phase). Real time data (contractile function via force transducer) was recorded from the TOBS using LabChart Pro, and a force frequency curve was plotted. Preliminary data suggest that SKM of both hibernators and non‐hibernators during the experimental hypothermia phase showed suppressed (and slow) contractile function in both species, with the lowest force values at 4 °C. However, during the recovery phase AGS displayed higher functional recovery from hypothermic conditions compared to SD. This evidence supports the fact that SKM of hibernating animals is expected to have higher adaptability and increased contractile functional recovery from thermal stress compared to SKM of non‐hibernating animals.Support or Funding InformationThis work was supported by the INBRE IDeA Faculty Pilot Grant (University of Alaska Fairbanks ) from NIH NIGMS grant number P20GM103395.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of Helicobacter pylori chemotaxis on gastric epithelial repair
Authors: Hanyu Hikaru , Engevik Kristen A. , Matthis Andrea L. , Ottemann Karen M. , Montrose Marshall H. , Aihara Eitaro 
Published: June 2021

BackgroundHelicobacter pylori (H. pylori) is a pathogen that contributes to the development of gastric inflammation. H. pylori chronically colonizes the stomach of approximately half of the world population. We previously demonstrated in vivo that H. pylori preferentially colonizes injury sites of the stomach. In this study, we used a reductionist model to determine if H. pylori chemotaxis was in response to molecular attractants intrinsic to the epithelium, and to investigate the necessary components of the H. pylori chemotaxis mechanism. We used gastric organoids (gastroids), a 3D primary culture of mouse gastric epithelial cells that mimics in vivo gastric epithelium.MethodsGastroids were generated from isolated corpus tissue of human GFP‐actin (HuGE) transgenic mice, and cultured 6–7 days prior to experiments. GFP fluorescence allowed tracking of epithelial repair, and Hoechst33342 (10 μg/mL) was added to visualize cell nuclei. Sydney strain 1 of wild‐type (WT) H. pylori or mutants defective in motility (ΔmotB), chemotaxis (ΔcheY), or individual chemoreceptors (ΔtlpA, ΔtlpB, ΔtlpC or ΔtlpD), were labeled with CellTrace™ Far Red fluorescent dye (1 μM). Brucella broth containing 106 H. pylori was microinjected (50 nL) into the lumen of gastroids. Brucella broth containing fluorescent beads (105) was microinjected into control gastroids.ResultsHigh intensity 730 nm light (two‐photon photodamage: PD) caused single cell damage in the gastroid, and repair of damage completed within ~10 min. WT H. pylori began to accumulate at the damage site 3–4 min after gastric damage induction, resulting in delayed repair. The H. pylori mutants ΔtlpA, ΔtlpC, and ΔtlpD also accumulated at the damage site and delayed repair. Fluorescent beads or H. pylori mutants ΔmotB, ΔcheY and ΔtlpB did not accumulate at the damage site, with only ΔtlpB and fluorescent beads not causing delayed repair.ConclusionH. pylori sense the damage site via chemotaxis, while motility is essential to complete this preferential accumulation. Data also suggests that H. pylori chemoreceptor tlpB plays an important role in sensing the damage site. As tlpB is reported to have a high affinity for urea, the damaged cell may be a source of high urea concentration.Support or Funding InformationFunded by NIH RO1 DK102551 (Montrose;Aihara) and Ryuji Ueno Award. Supported by “Tobitate! Study abroad scholarship”This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.