bluuebunny/crossref_metadata_2025_split huggingface dataset:
AVP‐mediated regulation of the paracellular permeability in the thick ascending limb (TAL)
Authors: Plain Allein , Marques Rita , Himmerkus Nina , Leipziger Jens , Bleich Markus 
Published: June 2021

The TAL drives an important part of the reabsorption of divalent cations. This occurs through the cation selective paracellular pathway. Arginine vasopressin (AVP) stimulates the transepithelial transport in the TAL. We wanted to study how AVP stimulation affects paracellular permeability in the TAL.TALs were mechanically dissected for microperfusion from 8‐10 weeks old mice who were kept for 4 days on water‐restricted (WR) (0.26ml/gBM/d) or water‐loaded (WL) (0.78ml/gBM/d) conditions, and from 5‐10 week old mice to be stimulated acutely with AVP.We measured transepithelial resistance and voltage (Rte, Vte), and calculated the equivalent short circuit current (Isc). From diffusion voltages, in presence of furosemide, we calculated the paracellular permeability (P) for Na+, Cl‐, Mg2+ and Ca2+. Measurements were performed at 37°C with continuous perfusion at a constant pressure.Freshly isolated TAL from the WR group (n=20) were transporting more actively compared to the WL group tubules (n=15). Vte and Isc were a 26% and a 48% higher, respectively, while Rte was 27% lower. Diffusion voltages were also increased in the WR group by 21%, indicating a 30% higher PNa/Cl, and a 27% higher PNa compared to WL.Acute TAL stimulation ex‐vivo for 12 minutes with AVP (n=6), in paired experiments, increased transepithelial transport. Isc and Vte increased by 23% and 25% respectively, while in the time control group Isc and Vte decreased by 28% and 37%. At the same time, AVP induced 20% more pronounced diffusion voltages compared to control, with a 25% increase in PNa/PCl.ConclusionWater restriction and AVP increase paracellular selectivity and permeability for cations in the TAL.
UROTHELIAL EPAC: NOVEL MEDIATOR IN THE REGULATION OF BLADDER CAPACITY
Authors: Nakagomi Hiroshi , Kullmann F Aura , Ruiz Wily , Wolf‐Johnston Amanda , Apodaca Gerard , Birder Lori 
Published: June 2021

Bladder filling elicits exocytosis and vesicle fusion increasing the apical surface area of epithelial cells (measured by membrane capacitance). One stimulus governing apical exocytosis is cAMP. Although initially the effects of cAMP were solely attributed to activation of protein kinase A (PKA), recent findings uncovered a novel c‐AMP sensor, EPAC (exchange protein directly activated by cAMP). This protein plays a critical role in calcium handling and ion transport, vesicle trafficking and secretion, and barrier function in various organs. Here we investigated the expression and role of EPAC in signaling apical membrane dynamics.Bladders from female Sprague Dawley rats and New Zealand white rabbits were used for western blot and immunohistochemistry or for culturing urothelial cells for fura‐2 calcium imaging and ATP release. Transepithelial capacitance was measured by placing bladder mucosa in modified Ussing chambers and increasing hydrostatic pressure to mimic bladder filling (in the presence or the absence of EPAC agonist‐ 8‐pCPT, or antagonist‐ ESI‐09).EPAC was expressed in the urothelium, however the agonist did not alter Ca2+ nor ATP release in cultured cells. Nevertheless, the EPAC agonist (used in rabbit UT) significantly increased transepithelial capacitance (30% vs 7% in control) in the absence of stretch; stretch‐induced capacitance was reduced by the EPAC antagonist.Our results indicate that EPAC plays an important role in augmenting bladder filling induced increases in urothelial surface area. The lack of ATP involvement suggests that EPAC mediated pathways could lead to increasing bladder capacity without affecting underlying bladder nerves.
A Renal Olfactory Receptor Aids in Glucose Handling in the Proximal Tubule
Authors: Shepard Blythe , Cheval Lydie , Doucet Alain , Pluznick Jennifer 
Published: June 2021

Olfactory receptors (ORs) are seven transmembrane‐domain G protein‐coupled chemosensors that detect odorants in the nose. We previously reported that ORs play roles in the kidney, and identified 9 renal ORs including Olfr1393. In reverse‐transcribed RNA from microdissected renal segments, Olfr1393 is exclusively expressed in the proximal tubule (PT; S1, S2 and S3). When stably expressed in polarized MDCK cells, Olfr1393 localizes to the apical plasma membrane (PM), but not to cilia. Because Olfr1393 is an “orphan receptor” with no known ligand, we screened over 1400 chemicals and found that Olfr1393 detects preconstrained cyclic molecules containing carbonyl or alcohol groups. To determine the physiological role of Olfr1393, we generated knockout (KO) mice. At baseline, KO mice are similar to wild‐type (WT) littermates with regard to plasma electrolytes, blood pressure and GFR (measured via iStat, tail cuff, and elimination kinetics of plasma sinistrin). However, despite being euglycemic, KO mice exhibit glycosuria (1.4x increase in glucose/creatinine vs WT) and can better handle a glucose challenge during a glucose tolerance test as indicated by plasma glucose values (area under curve: WT 22.4 ± 1.9 vs KO 15.7 ± 1.1; P = 0.001). These data suggest that Olfr1393 helps to regulate glucose reabsorption on the apical PM of the PT. In support of this, preliminary data suggests that heterologously expressed Olfr1393 can co‐immunoprecipitate with Sglt1 and Sglt2, the two Na+/glucose co‐transporters responsible for apical glucose reabsorption. We are currently examining the possibility that Olfr1393 influences the function of these transporters to regulate PT glucose handling.Funding: ASN, NIDDK
Time Course of Immune Cell Infiltration and Cytokine Production in the Kidneys of Dahl Salt‐Sensitive (SS) Rats
Authors: Petrova Galina , Mattson David 
Published: June 2021

Inflammation and immunity has been implicated in hypertension and renal disease in animals and humans. Previous studies from our lab have demonstrated that pharmacological or genetic inhibition of immune cell infiltration in the kidney attenuates salt‐sensitive hypertension and kidney damage in SS rats. The present studies were performed to assess the temporal infiltration of different immune cell subsets into the kidneys of Dahl SS rats when maintained on a low salt (0.4% NaCl, Day 0) diet and after 7, 14 and 21 days of high salt (4.0% NaCl) intake. Using a flow cytometry‐based approach, a progressive increase of infiltrating cells in the kidneys of Dahl SS was observed with time on the high NaCl diet. The total number of CD45+ cells (9.3±1.96 vs 35.2±6.8 x 105 cells/kidney), CD3+CD8+ cells (.69±.13 vs 1.9±0.2 x 105 cells/kidney) and CD3+CD4+ cells (.36±.08 vs 1.78±0.37 x 105 cells/kidney) significantly increased from Day 0 to 21 of a high salt diet (n=9‐17 rats/group). Stimulation of isolated kidney cells with PMA and ionomycin followed by intracellular cytokine staining revealed an increase in the number of IFN‐g producing CD8+ T cells and also in TNF, IFN‐g and IL‐17 producing CD4+ T cells (e.g. CD3+CD4+IL‐17+ cells increased from .05±.01 to .56±.16 x 105 cells/kidney from Day 0 to Day 21). IFN‐g and IL‐17 production by CD4+ T cells positively correlated with the number of regulatory T cells (increased from .09±.02 to .43±.01 x 105 cells/kidney from Day 0 to 21) and the total number of activated CD4+ T cells (increased from .14±.02 to .84±.02 x 105 cells/kidney from Day 0 to 21). These data indicate that the time course of immune cells infiltration and cytokine production by T cells parallels hypertension and kidney damage in Dahl SS rats fed a high salt diet.This work is supported by DK‐96859 and HL116264.
NH3 Permeability versus CO2 Permeability: Insights from Mathematical Modeling
Authors: Occhipinti Rossana , Boron Walter 
Published: June 2021

Exposing a cell to a solution containing NH3/NH4+ leads to a rapid NH3 influx, which causes a rise in intracellular pH (pHi) and a transient decrease in surface pH (pHS). Conversely, exposing a cell to a solution containing CO2/HCO3− leads to a rapid CO2 influx, which causes a fall in pHi and a transient increase in pHS.In our laboratory we use the maximal change in the height of the pHS transient (ΔpHS) as a semiquantitative index of membrane permeability to NH3 (PM,NH3) or to CO2 (PM,CO2). As a first step in extracting absolute membrane permeability from pHS measurements, in 2012 we developed a reaction‐diffusion mathematical model of CO2 influx to investigate the dependence of ΔpHS predicted by the model on PM,CO2 values (Somersalo et al, J Theor Biol, 2012). To account for physiological data on gas channels, the model predicts that,contrary to widespread assumptions, the membrane must offer considerable resistance to the movement of CO2.Here, we investigate the dependence of ΔpHS versus PM,NH3 with a reaction‐diffusion mathematical model of NH3 influx into a spherical cell. The model is an extension of the model of Somersalo et al, in which now we include the NH3/NH4+ buffer equilibrium and passive transmembrane flux of NH3. After having checked that the model correctly predicts the transient changes in pHi and pHS that one would expect as NH3 enters a cell, we performed simulations in which we systematically decreased PM,NH3 from that corresponding to a thin film of water. By comparing the dependence of ΔpHS versus a range of PM,NH3 (present study) with the dependence of ΔpHS versus PM,CO2 (Somersalo et al), we conclude that, contrary to the Overton's prediction (which considers only solubility in the membrane), the background PM,NH3 (in absence of gas channels) is far higher than the background PM,CO2.
The efficacy of adipose‐derived stem cells sheet in preventing pancreatic fistula following pancreas body transection in rats
Authors: Kaneko Hirokazu , Yokoyama Yukihiro , Yamaguchi Jyunpei , Yamamoto Tokunori , Shibata Rei , Kokuryo Toshio , Nagino Masato 
Published: June 2021

BACKGROUNDA pancreatic fistula (PF) is one of the most common and fatal complications after pancreatic resection. Thus the prevention of PF is urgent in pancreatic surgery. However, there is no effective strategy in preventing PF.AIMWe studied the efficacy of adipose tissue‐derived stem cells (ADSCs) sheet with mannose for the prevention of PF in rat pancreatic fistula model.METHODSWister rats underwent transection of the pancreas body to develop PF. ADSCs cultured in sheet form were made and applied to the transected pancreatic stump. Rats were allocated to the following three groups; non‐treatment (n=9), ADSCs sheet treatment (n=5), ADSCs sheet treatment with mannose (n=5) groups. The amylase and lipase levels were measured in the ascetic fluid at two days after operation.RESULTSAscitic amylase levels were (107±30)×103 U/L in the non‐treated group, (26±10)×103 U/L in the ADSCs sheet group, and (15±3)×103 U/L in the ADSCs sheet with mannose group. The levels were significantly lower in the ADSCs sheet with mannose group compared to the non‐treated group(P= 0.04). Lipase levels also showed a similar trend in ascitis. Intra‐peritoneal lipolysis was minimum in the ADSCs sheet with mannose group compared to other groups.CONCLUSIONThe application of ADSCs sheet on the pancreatic stump is effective in preventing PF. Adding mannose enhanced the effect of ADSCs sheet. We are now investigating the molecular mechanisms of ADSCs sheet concerning tissue repair process.
Cerebral Blood Flow Velocity and Cognitive Function Preceding Post‐Exercise Syncope
Authors: Sieck Dylan , Luttrell Meredith , Romero Steven , Ely Mathew , Halliwill John 
Published: June 2021

Adequate cerebral perfusion is necessary to maintain consciousness in the upright human. Following maximal anaerobic exercise, cerebral perfusion can become compromised as evident by post‐exercise syncope. It is unknown whether post‐exercise reductions in cerebral perfusion after exercise lead to cognitive deficits prior to the onset of syncope, which would be of utmost concern in populations such as emergency workers and soldiers. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood flow velocity induced by maximal anaerobic exercise and head up tilt lead to visual/cognitive deficits prior to the onset of syncope. We hypothesized that a modified Wingate test followed by a head‐up tilt would reduce cerebral blood flow velocity and result in visual/cognitive deficits prior to the onset of syncope. Ten recreationally active volunteers were subjected to a symptom‐limited 60° head‐up tilt for up to 16 min before and after a 60‐s Wingate test. Blood flow velocity of the middle cerebral artery was measured via transcranial Doppler ultrasound and a visual decision‐reaction time test was assessed in the peripheral visual field. Cerebral blood flow velocity decreased as tilt progressed from 49.6 ± 3.2 to 46.2 ± 2.4 cm/s (mean ± SE; p < 0.05). Also, peripheral decision‐reaction time increased as tilt progressed from 363.7 ± 12.7 to 385.3 ± 18.4 ms (p < 0.05). These data suggest that the reduction in cerebral blood flow velocity following maximal anaerobic exercise contributes to cognitive deficits as evidenced by the concurrent increase in peripheral field decision‐reaction time prior to syncope.Support provided by NIH grant HL115027
Estrogen Source Influences Muscle Soreness and Recovery in Young Women
Authors: Anderson Lindsey , Baker Lucinda , Schroeder E Todd 
Published: June 2021

Methods100 contractions of maximally tolerated neuromuscular electrical stimulation (NMES) were performed on one quadriceps. The oral contraceptive (OC) group, consuming an exogenous estrogen source, performed NMES between days 8‐11 of pill consumption. The high (HI) and low (LO) endogenous estrogen groups performed NMES between days 19‐21 or 1‐3 of the menstrual cycle, respectively; day 1 was menses onset. HI and LO did not take OC. Maximal voluntary isometric contraction (MVIC) was assessed before, 0, and 48 hours post. Soreness was measured before and 48 hours post with a 7‐point and 10‐point Likert Scale of Muscle Soreness for Lower Limb (LSMSLL) and a 100 mm visual analog scale (VAS). Maximum and average Rating of Perceived Exertion (RPE) and Pain were reported for the NMES bout.ResultsMean maximum (15.9) and average (13.8) RPE were similar across groups. HI reported 2‐3 points lower mean maximum and average Pain than OC or LO.

OC (N=5)
HI (N=2)
LO (N=2)

Age (years)
25 (3)
25 (1)
27 (3)

BMI (kg/m2)
23.2 (1.4)
22.6 (4.7)
24.1 (3.8)

Body Weight (kg)
63.9 (5.3)
58.1 (12.0)
65.5 (7.4)

Lean Mass (kg)
45.9 (3.4)
41.7 (3.6)
41.3 (2.8)

Percent Fat
27.8 (5.9)
27.4 (8.7)
32.2 (17.3)

NMES

MVIC (N)
335.4 (49.6)
355.5 (41.0)
263.1 (96.1)

%MVIC (avg NMES force)
34.2 (7.7)
44.8 (3.6)
43.3 (26.0)

%MVIC (0 hrs post)
86.4 (18.3)
82.7 (4.6)
71.4 (3.2)

%MVIC (48 hrs post)
97.4 (7.6)
86.4 (11.0)
91.1 (40.4)

Soreness

Delta_VAS (mm)
380.5 (196.4)
587.5 (116.7)
375.0 (176.8)

Delta_7 pt
2.8 (0.8)
4.0 (0.7)
3.8 (1.1)

Delta_10 pt
4.2 (1.9)
5.8 (1.8)
6.0 (2.8)

ConclusionThese results are interpreted with the knowledge that this is an ongoing study with recruitment goals of N=7 per group. Given the current small sample size and large variability, exogenous estrogen may increase exertion perception as OC did less work and experienced less soreness and faster recovery than HI and LO despite higher lean mass and similar exertion rating. Either source of estrogen may decrease immediate post‐exercise fatigue as LO displayed a greater degree of strength loss at 0 hours post NMES despite doing similar work to HI and more work than OC. Future analysis requires covarying for absolute force and lean mass.
Enhanced Muscle Mass and Contractile Function Recovery via Resistance Training after VML Injury
Authors: Song Taejeong , Lee Kwangjun , Farrar Roger 
Published: June 2021

Volumetric muscle loss (VML) is traumatic muscle injury that causes irreversible loss of muscle mass and permanent deficit of muscle function. Decellularized muscle scaffold has been utilized to fill the defected area and provide platform for muscle regrowth, but it has limited effects on recovering muscle mass and contractile functions. Thus additional intervention is required for promoting restorations of muscle mass and function after the VML injury.PURPOSETo test effects of resistance exercise on muscle mass and functional recoveries after VML injuryMETHODS1×1cm full thickness proximal portion of later gastrocnemious (LGAS) was cut to induce VML injury of adult rats. About 19% of total LGAS mass was removed from one leg and decellularized porcine skeletal muscle extracellular matrix (ECM) was transplanted in the defected site connecting remnant of muscle. Ladder climbing exercise started ten days after the injury. Every third day, the mechanical load of the resistance training was increased each bout. In‐situ peak tetanic tension of LGAS was measured at 8 weeks after the injury followed by measuring length and mass of LGAS.RESULTSProgressive resistance training utilizing ladder climbing exercises significantly improved recovery of LGAS muscle mass (88% of contralateral LGAS) compared to that of sedentary control (77%)(P<0.05). Peak tetanic tension of injured LGAS recovered 90% of contralateral LGAS in exercised group, but it was only reached 75% of non‐injured LGAS in the sedentary control. The specific tension of the LGAS of the trained group was same as control muscle.CONCLUSIONResistance exercise treatment has beneficial effect on restoration of muscle mass, and it also enhanced functional recovery of defected LGAS muscle after VML injury.
Respiratory Monitoring System for Underwater Use
Authors: Warkander Dan , Boone Henry , Shykoff Barbara 
Published: June 2021

Monitoring a diver's respiratory parameters is a challenge. A respiratory monitoring system (RMS) should allow measurements of gas flows, gas composition (O2 and CO2, breath by breath) and pressure swings at the mouth. For physiologic research, breathing resistance and gas composition should be independently adjustable. The pressure of the breathing gas relative to the diver's lung centroid (static lung loading, hydrostatic imbalance) should be controlled. Ideally, an RMS has no depth limitations.In the RMS described here, the diver breathes through a full face mask and large bore hoses to an inspiratory and an expiratory side. Each side has a flow meter and temperature and pressure (relative to the mask) sensors. The inspiratory side is supplied with a constant, surface‐adjustable gas flow to a bag from which the diver breathes. This flow is adjusted to keep the bag full at the beginning of inhalation. Excess gas bubbles into the water. Expiration is buffered by another bag and bubbles into the water.Gas from the mask is sampled to a mass spectrometer for continuous analysis. The flow meter, mass spectrometer, pressure and temperature signals are displayed in real time and recorded.The prone diver is positioned on a cycle ergometer that keeps the chest in a known position relative to the RMS. The depth of the exhaust ports of the RMS relative to the diver's lung centroid controls hydrostatic imbalance. Resistance elements can be added to either breathing hose. The size and shape of the breathing bags set elastic loads.Breathing gas with selected concentrations of O2 and CO2 permits assessment of gas composition effects on respiratory performance when a diver is challenged by experimenter‐imposed respiratory impediments. The RMS has been used in a pool at a depth of about 3 m in close to 100 experiments without incident.
Renal angiotensin II content in neonates is influenced by the salt intake during pregnancy
Authors: Seravalli Priscila , Zago Breno , Oliveira Ivone , Veras Mariana , Heimann Joel 
Published: June 2021

ObjectiveThis study aims to evaluate a possible influence of high‐ or low‐ salt intake during pregnancy on renal structure and renin‐angiotensin system in neonates in Wistar rats.MethodsPregnant rats were fed with normal, high or low‐salt diet (NR, HO and HR groups, respectively) from the first day of pregnancy until delivery. Kidneys of the newborns (6‐8/group) were collected in the first 24 hours of life. Total renalvolume (stereology) and kidney renin‐angiotensin system (indirect ELISA) were evaluated.Results (mean±SEM, p<0.05)

HO
NR
HR
Statistical analysis

Dams weight (g)

351±23*
377±36
386±42
p&lt;0.05 vs HR

Liter size (n)

14±0.82
14±0.65
14±0.53
NS

Newborns

Body weight (g)
male
5.37±0.09*
6.47±0.07
6.45±0.08
p&lt;0.0001 vs NR and HR

female
5.13±0.07*
6.05±0.09
5.99±0.08
p&lt;0.0001 vs NR and HR

kidney weight (g)
male
9.43±0.27
9.91±0.21
9.25±0.37
NS

female
10.22±0.32
9.99±0.22
9.66±0.22
NS

kidney volume (mm³)
male
7.04±0.47
7.44±0.22
8.20±0.46
NS

female
6.73±0.61
5.84±0.44
7.25±0.98
NS

ANG II (%)
male
75±6.33*
100
68.1±4.05*
p&lt;0.05 vs NR

ACE (%)
male
95.4±13.5
100
82.5±6.68
NS

ConclusionLow salt intake during pregnancy is associated with low birth weight. Renal angiotensin II content compared normal salt fed dams is lower in newborns from salt overloaded and restricted dams during pregnancy.
Murine Pulmonary Slowly‐Adapting Receptors (SARs): Putative links to Neuroepithelial Body (NEB) hypoxia chemoreception and the Calcium Sensing Receptor (CaSR)
Authors: Domnik Nicolle , Vincent Sandra , MacLeod R John , Cutz Ernest , Fisher John 
Published: June 2021

Pulmonary SARs are mechanosensitive vagal afferents, which Adriaensen (J Appl Physiol, 2006) proposed to be functionally linked to morphologically‐defined, hypoxia‐sensitive NEBs (Youngson et al. 1993, Nature). Post‐natal NEBs express CaSR (Lembrechts et al. 2013, J Cell Sci), and vagal NEB innervation expresses P2X2 and P2X3 ATP receptors (Brouns et al. 2009, Histochem Cell Biol). We tested in vivo murine SAR responses to quasi‐static inflation (0‐20 cmH2O) in: 1) hypoxia (10% O2) 2) absence of CaSR (CaSR / parathyroid hormone double‐knockout mouse, KO) and 3) P2 purinergic receptor blockade (Suramin: 50 mg/kg). SAR mechanosensitivity was defined as action potential frequency (f) at tracheal pressures of 5, 10, 15, and 20 cmH2O. Hypoxia caused a small but statistically significant increase in f (9.6±2.8% at 20cmH2O; P = 0.002, mean±SEM). Loss of CaSR significantly reduced f at all pressures (‐34.9% and ‐39.5% at 15cmH2O in hyper‐ and hypoxia, respectively; P < 0.001) with no impact of hypoxia within each genotype. Suramin caused a small but significant reduction in f (‐10.6±1.5% at 20cmH2O; P = 0.01). These data suggest that CaSR significantly impacts SAR mechanosensitivity, while purinergic signaling and hypoxia exert modest effects with as yet to be determined physiologic roles.Supported by CIHR MOP81211 (JTF), Spear Endowment for Respiratory Research (Queen's University JTF and RJM), NSERC PostGrad Scholarship (NJD).