bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevation in fibrinogen content affects the tight junction proteins and increases endothelial cell permeability
Authors: Tyagi Neetu , Dean William L. , Roberts Andrew M. , Tyagi Suresh C. , Lominadze David 
Published: June 2021

Mechanisms of fibrinogen (Fg)‐induced endothelial cell (EC) permeability were assessed by measuring transendothelial electrical resistance using an electrical cell‐substrate impedance system (ECIS). Rat cardiac microvascular ECs were grown either in gold plated ECIS's chambers or in regular 6‐well plates. Confluent ECs were treated with Fg (2 or 4 mg/ml), Fg (4 mg/ml) with extracellular signal‐regulated kinase (ERK) kinase inhibitor (PD98059), or medium alone for 24 hours. Resistance values from each microelectrode were collected and plotted as relative resistance vs. time. Western blot analysis was pdone to determine the changes in tight junction proteins of the ECs treated with Fg (2mg/ml or 4 mg/ml) or medium alone for 24 hours. The higher dose of Fg (4 mg/ml) induced greater EC layer permeability compared to that induced by the lower dose or by medium alone. Fg‐induced increase in EC permeability was inhibited by PD98059. Treatment of EC with 4 mg/ml of Fg significantly decreased the content of occludin in ECs. These data suggest that Fg increases EC permeability through ERK signaling, affecting occluding, which is one of the tight junction proteins that is known to be bound to actin filaments.Supported by NIH grant# HL080394 to DL.
Regulation of ENaC by small G proteins
Authors: Staruschenko Alexander 
Published: June 2021

Small G proteins are recognized to regulate diverse cellular processes. We have shown previously that the epithelial Na+ channel (ENaC) is regulated by Ras and Rho GTPases. K‐Ras, RhoA and Rac1 markedly increase activity of ENaC reconstituted in CHO cells in a GTP‐dependent manner. However, their transductionpathways and mechanisms of activation are different; K‐Ras increases channel open probability via PI3‐kinase signaling, whereas RhoA increase channel membrane levels. Regulation of ENaC open probability by PI3‐kinaseis a direct consequence of the physical association of the product of PI3‐kinase, PI(3,4,5)P3with the channel. RhoA activates ENaC via Rho‐kinase and subsequent activation of PI(4)P5‐kinase with concomitant increases in PI(4,5)P2 levels promoting channel insertion into the plasma membrane. Recent studies reveal that multiple Rab isoforms physically interact with and/or modulate the activity of several ion channels. Rab11a is well‐established as a participant in the regulation of recycling endosomal trafficking. Rab11a is associated with vesicles in the apical portion of epithelial cells near the centrosome and beneath the apical plasma membrane. Co‐expression of Rab11a with ENaC results in a significant increase in channel activity. We conclude that Rab11a may be important in the trafficking of ENaC.Supported by AHA.
Regulation of ENaC‐mediated sodium transport by glucocorticoids in Reissner's membrane epithelium
Authors: Kim Sung Huhn , Raveendran Nithya N. , Kim Kyunghee , Harbidge Donald G. , Sanneman Joel D. , Marcus Daniel C. 
Published: June 2021

Reissner's membrane (RM) epithelium forms much of the barrier that sustains the large ionic differences between cochlear endolymph and perilymph. We reported that RM contributes to normal cochlear function by absorption of Na from endolymph via the epithelial sodium channel (ENaC) in gerbil inner ear [Lee et al, Neuroscience, 2003].In the present study, we sought in mouse RM 1) to determine the presence of genes involved in the Na transport pathway, 2) to determine whether their level of expression was regulated by corticosteroids using gene array and quantitative RT‐PCR and 3) to obtain functional evidence for these genes by electrophysiologic and pharmacologic means. Transcripts were present for the α‐, β‐, γ‐subunits of ENaC; the steroid receptors GR (glucocorticoid receptor) and MR (mineralocorticoid receptor); the GR agonist‐regulator 11β‐HSD1; Na transport control components Sgk1 and Nedd4‐2. Expression of the MR agonist‐regulator 11β‐HSD2 was near the lower limit of detection. Dexamethasone upregulated transcript expression of α‐ and β‐subunits of ENaC (∼6 and ∼3 fold). Currents directed into the endolymphatic face of RM were sensitive to amiloride and benzamil, but not EIPA. The currents were also inhibited by ouabain and K‐channel blockers (TEA and clotrimazole). These molecular and functional observations are consistent with Na absorption by RM in the mouse that is mediated by apical ENaC, basolateral Na‐pump and K channels, and that is under the control of glucocorticoids but not mineralocorticoids. These results provide an understanding and molecular definition of one possible mode of therapeutic action of glucocorticoids in the treatment of Meniere's disease.Supported by NIH grants R01‐DC00212, P20‐PR017686.
NOP receptor stimulation by ZP120 induces anti‐natriuresis through a direct effect on epithelial sodium channel (ENaC) in the renal collecting duct
Authors: van Deurs Ulla Seehusen Kruchov , Hadrup Niels , Petersen Jørgen Søberg , Christensen Sten , Jonassen Thomas 
Published: June 2021

ZP120 is a peptide analogue of the endogen peptide nociceptin, which has been shown to have marked aquaretic effects in vivo. However, in addition to this effect ZP120, at least during sodium replete conditions, seems to induce an anti‐natriuretic effect by an unknown mechanism.The aim of this study was to identify the specific tubular segment where ZP120 facilitates its sodium retaining effects.The acute effect of ZP120 (1 nmol/kg/min) infusion was examined in chronic catheterized, conscious rats by clearance technique. The rats received a basal infusion of 3 ml/h of isotonic saline throughout. During these conditions ZP120 induced marked diuresis (71 ± 8 vs time control: 12 ± 1 μl/min/100 g BW) whereas urinary sodium excretion decreased in the ZP120 infused compared to time controls (−42± 5 vs time control: 14± 13 umol/min/100 g BW).90 min ZP120 infusion was followed by coadministration of bendroflumethiazide (BFTZ) or amiloride to block the thiazide sensitive cotransporter in the distal convoluted tubules or the Epithelial Na+ Channel in the collecting ducts. Rats treated with BFTZ or amiloride acted as controls. The natriuretic response to BFTZ was similar in ZP120 treated animals and controls, whereas the natriuretic response to amiloride was increased by 63 % when compared to controls.These results strongly suggest a direct stimulatory effect of ZP120 on the Epithelial Na+ Channel in the kidney collecting ducts.
Rats bred as low intrinsic aerobic capacity runners (LCR) recover more slowly from chronic pain compared to rats bred as high intrinsic aerobic capacity runners (HCR)
Authors: Muncey Aaron R. , Saulles Adam , Baghdoyan Helen A. , Koch Lauren G. , Britton Steven L. , Lydic Ralph 
Published: June 2021

Low physical fitness and obesity are associated with chronic pain (J Pain 8: 430, 2007) and the mechanisms underlying this link are difficult to explore in humans. This study is testing susceptibility to experimentally induced chronic pain in two rat strains developed by two‐way artificial selection on a treadmill to contrast for both intrinsic (untrained) fitness and obesity. Experiments were performed using generation 19 LCR (n=3) and HCR (n=3) males. Pain threshold was measured as paw withdrawal latency (PWL) to a nociceptive thermal stimulus using an IITC Hargreaves system. PWL was measured before and weekly for six weeks after chronic constriction injury (CCI) of the sciatic nerve, a validated model of neuropathic pain (Pain 33: 87, 1988). PWL did not differ between HCR and LCR rats before CCI. Two‐way ANOVA for repeated measures showed that PWL varied significantly as a function of aerobic capacity, time after CCI, and by interaction. At days 21, 28, 35, and 42 after CCI the LCR rats had a 23% shorter PWL than the HCR rats. The finding that CCI produced a shorter PWL in LCR compared to HCR rats is consistent with the hypothesis that a low aerobic capacity phenotype is associated with greater hyperalgesia. Thus, LCR and HCR rats may provide contrasting models of susceptibility to chronic pain relevant for mechanistic studies in humans.Support: NIH grants HL6427, RR‐17718, HL57120, HL40881, MH45361 and Dept Anesthesiology
Differences in muscle protein synthesis and anabolic signaling in the postabsorptive state and in response to food in 65–80 y old men and women
Authors: Smith Gordon Ian , Atherton Philip , Villareal Dennis T. , Rennie Michael J. , Mittendorfer Bettina 
Published: June 2021

Men have more muscle than women but during aging lose muscle faster than women. To investigate potential mechanisms responsible for this we measured rates of muscle protein synthesis (MPS) with stable isotope‐labeled tracer techniques and the phosphorylation status of anabolic signaling elements during postabsorptive conditions and feeding in men (n=13) and women (n=16) who were matched on age (65–80 y) and body mass index. Postabsorptive MPS was ∼25% less in men than in women (0.045 [0.039; 0.057] vs 0.058 [0.052; 0.072]; %·h−1; medians [quartiles]; P=0.02) and feeding increased MPS in men (to 0.071 [0.059; 0.079] %·h−1; P<0.01) but not women (0.060 [0.056; 0.089] %·h−1). Postabsorptively, muscle phosphorylated AktSer473, p70s6kThr389, eIF4ESer209 and eIF4E‐BP1Thr37/46 concentrations were not different between sexes but that of eEFThr56 was less in women, consonant with more activated protein elongation. Accordingly, feeding increased eIF4ESer209 and eIF4E‐BP1Thr37/46 phosphorylation in men (both P<0.05) but not in women. Thus, there is sexual dimorphism in MPS and its control in older adults with a diminished basal rate of MPS, which operates over much of the day, potentially explaining the faster loss of muscle in older men.This research was supported by grants from the US NIH, the University of Nottingham, the UK BBSRC, and the European Union.
Fatty acid induced NF‐κB activation and insulin resistance in skeletal muscle are chain length dependent
Authors: Hommelberg Pascal , Langen Ramon C.J. , Plat Jogchum , M.W.J. Schols Annemie , Mensink Ronald P. 
Published: June 2021

Palmitate‐induced insulin resistance has been associated with inflammatory signaling in cultured skeletal muscle cells. The aim of this study was to evaluate if other saturated fatty acids (SFA) also exert these effects on skeletal muscle and whether these relate to chain length. In differentiated L6 GLUT4‐cMyc myotubes, we observed a decrease in insulin stimulated GLUT4‐cMyc translocation to the cell membrane after incubation with the long chain SFAs palmitic (C16:0) and stearic (C18:0) acid. However, incubation with equimolar amounts of the medium chain SFAs caprylic (C8:0) and lauric (C12:0) acid did not affect insulin sensitivity in these cells. In addition, in C2C12 myotubes with a genomically integrated Nuclear Factor kappa B (NF‐κB) reporter gene, C16:0 and C18:0 increased NF‐κB transcriptional activity, while the SFA with shorter chain lengths (C8:0 and C12:0) were not able to elevate NF‐κB transcriptional activity.In conclusion, we have shown that SFA‐induced insulin resistance only occurs in response to long‐chain but not medium‐chain fatty acids and is associated with NF‐κB activation. The exact mechanisms underlying these differential effects of SFA on insulin resistance and NF‐κB activation remain to be investigated, but this finding supports the notion that inflammatory signaling in skeletal muscle may be regarded as a target for improving or restoring insulin sensitivity.
Hepatocyte Growth Factor Signaling in Mediating Human Muscle Satellite Cell Activation and Proliferation Following Eccentric Exercise
Authors: McKay Bryon Robert , O'Reilly Ciara E. , Kawka Stefany , Phillips Stuart M. , Tarnopolsky Mark A. , Parise Gianni 
Published: June 2021

Eight subjects (20.6 ± 2.1 yr; 81.4 ± 9.8 kg) performed 300 isolateral eccentric contractions (knee extensions at 180 °/s) to evaluate the skeletal muscle satellite cell (SC) response and the potential of hepatocyte growth factor (HGF) signaling in mediating SC activation and proliferation following acute damaging exercise. Muscle biopsies were obtained from the vastus lateralis of the non‐exercised leg prior to exercise (PRE) and the exercised leg at 4 (T4), 24 (T24), 72 (T72), and 120 h (T120) post‐exercise. The number of SC (N‐CAM+) increased (p < 0.001) by T4 and remained elevated at T120 (p = 0.002). Serum HGF increased at T4 (p < 0.05) with a trend for increased muscle HGF and HGF activator (HGFA) protein expression at T24 with active HGF detected in all PRE samples. HGFA inhibitors (HAI‐1 and HAI‐2) protein content increased at T72 and remained elevated at T120 (p < 0.05). Myogenic regulatory factors (MyoD and Myf5) mRNA expression increased at T4 and T24 (p < 0.05) respectively, with increased myogenin mRNA expression at T24 (p < 0.05). Furthermore, plasma interleukin‐6 concentration increased ∼200% (p < 0.05) by T4, illustrating a roll of both local and systemic signaling in the activation and proliferation of SC; with HGF signaling playing an important regulatory role in the SC response to exercise‐induced muscle damage.Supported by NSERC
Mechanisms involved in cAMP mediated inhibition of the Ubiquitin‐Proteasome system
Authors: Lira Eduardo Carvalho , Gonçalves Dawit Albieiro , Zanon Neusa M. , Baviera Amanda M. , Bedard Nathalie , Wing Simon S. , Kettelhut Ísis do Carmo , Navegantes Luiz Carlos 
Published: June 2021

Aim: This study was undertaken to investigate the role of beta‐2 adrenoceptors and cAMP in regulating the Ubiquitin‐proteasome system (UPS) in skeletal muscle from normal rats.Methods and results: The activity of UPS and the Akt/FoxO signaling pathway were measured in skeletal muscle from rats treated with clenbuterol (3 mg/kg wt; sc), a selective beta‐2 adrenergic agonist, for 3 days. In extensor digital longus (EDL) muscle, clenbuterol increased by 30% muscle weight, reduced by 45% the UPS activity and increased by 30% the phosphorylation of Akt and FoxO3. The addition of isobutylmethylxanthine (IBMX; 10−3M), a cAMP phosphodiesterase inhibitor, to the incubation medium increased cAMP levels (4‐fold) and decreased by 50% the UPS activity in isolated soleus and EDL muscles from normal rats. IBMX in vitro also reduced the levels of ubiquitin‐protein conjugated and the mRNA levels of the atrogin‐1/MAFbx (50%) and the E2‐14KDa ubiquitin conjugating enzyme (30%) transcripts in muscles from normal rats. Ubiquitin and MuRF1 mRNA were not altered by IBMX in vitro.Conclusions: These data suggest that stimulation of beta‐2 adrenoceptors, through the activation of cAMP and Akt signaling pathways, inhibit ubiquitin‐proteasome proteolysis by increasing FoxO3 phosphorylation and suppressing atrogin‐1 mRNA expression in skeletal muscle from normal rats.Financial support: CNPq, CAPES, FAPESP
A NOVEL REGULATORY ROLE FOR THE LACTATE ION ON EXCITABILITY AND FORCE
Authors: de Paoli Frank Vincenzo , Jørgensen Rasmus , Pedersen Thomas Holm , Ørtenblad Niels , Nielsen Ole Bækgaard 
Published: June 2021

We examined the effect of lactate (lac) per se on excitability and tetanic force development. Rat soleus muscles were incubated in KR‐buffer (95% O2) containing 20 mM Na‐methanosulfonate (MS). Lac was added as Na‐lac and an equimolar of MS was omitted to maintain osmolarity and constant Na+ and Cl− concentrations.Elevation of [K+]o to 11 mM reduced M‐wave area and force in muscles stimulated via the nerve to 16 and 17% of control values at 4 mM [K+]o, respectively. Subsequent addition of 20 mM lac recovered M‐wave area and force to 53 and 70% of control values at 4 mM [K+]o, respectively. In similar experiments with field stimulation, the force recovered from 29 to 88% of control values at 4 mM [K+]o. 20 mM lac reduced pHi from 7.19 to 7.06 within 40 sec, followed by a recovery of pHi to 7.21 over the next 45 min. We have previously shown that a reduction in pHi can lead to force recovery in K+ depressed muscles, it was of interest to estimate to what extend the reduction in pHi after addition of lac was responsible for the recovery of force. The reduction in pHi induced by lac was mimicked by increasing CO2 to 7%, which reduced pHi from 7.19 to 7.04. This pHi reduction, however, only produced a negligible and insignificant recovery of force in muscles depressed by elevated [K+]o. Conclusion: In K+ depressed muscles, a physiological increase in intracellular lac restores excitability and force.Danish Medical Research Council: j.nr. 271‐05‐0304
The expression of cofilin‐1 via PKC pathway induced by hyperglycemia in endothelial cells
Authors: Liu Yongming , Wang Yinfang , Wang Fengjie , Deng Juan , Wu Dehong , Su Hui , Zhang Yemin , Wang Nian , Zhang Deling , Ouyang Jingping 
Published: June 2021

Cofilin is an important cytoskeletal associated protein which regulated the actin fiber. Our aim is to research the associated relation between the expression of cofilin‐1 and the regulative effect of protein kinase C(PKC) in endothelial cells induced by hyperglycemia.Methods: Endothelial cell line (ECV304) was routinely cultured in low glucose DMEM medium as control (5mmol/L), and then were treated with high glucose (25mmol/L) and different factors for 24h. Activity of protein kinase C (PKC) within the cells was detected by PepTag non‐radioactive detection assay (Promega). The expression of cofilin‐1 and actin was detected by Western blot, the distribution of actin fiber was labeled by fluorescent probe Alexa‐488 and detected by Confocal (Leica).Results: The activity of PKC within cells obviously increased (p<0.01), and the expression of cofilin‐1 significantly strengthened after stimulation of hyperglycemia (p<0.01). The cells were pretreated with GF109203X (PKC inhibitor), the activity of PKC which increased formerly by hyperglycemia was apparently inhibited(p<0.01), and expression of Cofilin‐1 was also inhibited(p<0.05). But GF109203X had no apparent effect on the expression of cofilin‐1 and activity of PKC within low‐glucose cultured cells.Conclusion: The high‐glucose can improve the expression of cofilin‐1 through PKC signaling pathway. It may be an important pathogenesis for diabetic vascular complications.The research is granted by“ChenGuang Youth Scientific Project of Wuhan”(20015005045).
A new and simple method for detecting non‐invasive vascular endothelial function in mice
Authors: Furuta Tomoaki , Matsushita Shonosuke , Sugimori Haruhiko , Sato Fujio , Sakakibara Yuzuru 
Published: June 2021

Purpose: The importance of non‐invasive measuring of vascular endothelial function is widely recognized. However, it has not been established in mice as far as we know. From this background, we tried to establish a new method to measure a vascular endothelial function through nitric oxide (NO) mediated vasodilation.Method: Mouse hindlimb (n = 6) was compressed for a short time (30 seconds) and released immediately. The arterial blood flow was measured continuously using laser Doppler flow meter at arcus plantaris.Result: Reactive hyperemia (127+/−10% from baseline) at reperfusion was reproducibly‐observed. This reaction was mostly inhibited by L‐NAME (5mg/kg i.p.) (107+/−5%, p<0.005 vs. without L‐NAME). And it was completely‐recovered by supplying exogenous NO (122+/−16%, p<0.05 vs. after L‐NAME). Therefore, this method was considered to reflect NO‐mediated endothelial function. On the other hand, this was not inhibited by non‐selective cyclooxygenase inhibitor indomethacin (IDM; 20 mg/kg i.p.) (baseline: 120+/−11 vs. after IDM: 128+/−10%, p:NS).Conclusion: From these results, we confirm that this method is a new and simple technique measuring NO‐mediated endothelial function non‐invasively in mice.
Plasma catecholamine responses are consistent among common laboratory stressors
Authors: Elvebak Rachel L. , Liu Z. , Hesse C. , Marrero FA Ramirez , Pike TL , Gleich SJ , Eisenach JH 
Published: June 2021

Cardiovascular reactivity to stress may be predictive of cardiovascular disease. Sympathoexcitatory responses to mental stress (MS), cold pressor test (CPT), isometric handgrip (HG) and head‐up tilt (HUT) target different physiological mechanisms, but the correlation between response variables is unclear. Our purpose was to test the hypothesis that pressor and catecholamine responses between these stressors would be correlated within subjects. Healthy, normotensive young adults (n=76) underwent MS, CPT, HUT and HG to fatigue. Arterial pressure and HR were monitored, and arterial Epi and NE were sampled during the final 30 sec of each stressor. Percent change from baseline was averaged during MS, CPT, HUT and the final 20% time segment of HG. MAP and SBP were positively correlated between CPT and HG (r = 0.46, 0.52, resp, p < 0.001) but not among other tests. Interestingly, the % increase in NE response to all 4 maneuvers showed robust correlations (MS v CPT r = 0.65; MS v HG r = 0.74; MS v HUT r = 0.53; CPT v HG r = 0.72; CPT v HUT r = 0.68; HG v HUT r = 0.59; p < 0.001 for all). Similar correlations were present for Epi except for comparisons with HUT. This suggests that among the 4 tests, HR and BP responses are generally variable, but NE and Epi responses are remarkably consistent (except Epi for HUT), implying that lab stressors may evoke sympathoexcitation more similarly than previously thought.Support: K23‐RR17520, HL 46493.
Non Invasive Evaluation of Cardiac Dysfunction in β‐thalassemic Mice
Authors: Stoyanova Ekatherina , Cloutier Guy , Felfly Hady , Trudel Marie 
Published: June 2021

Beta‐thalassemia is a genetic hematological disorder characterized by mutations of the hemoglobin gene causing total or partial decrease of the β‐globin chain production. This disease leads to a chronic hemolytic anemia, cardiac complications and blood circulatory problems such as transitory ischemic attacks, thromboembolic events and microcirculatory obstructions. Our objective is to study and dissect the molecular physiologic mechanism of cardiovascular dysfunction in β‐thalassemia. We have generated a murine model of β‐thalassemia major primarily for the investigation of the cardiovascular physiology. Left ventricular morphology and function were assessed by echocardiography in 13.5‐month‐old β‐thalassemic mice and age matched controls. The left ventricular mass index and total peripheral vascular resistance were significantly increased (p < 0.05 and p < 0.01, respectively) in β‐thalassemic mice compared to wildtype controls. Furthermore, fractional shortening and cardiac output index were significantly decreased (p < 0.01) in β‐thalassemic mice compared to age matched controls. Thus, these data in β‐thalassemic mice showed left ventricular remodeling by dilatation and hypertrophy that likely play a key role in cardiac dysfunction.This work was supported by the NIH (#RO1HL078655), CIHR (#CMI 72323), HSFC (#PG‐05‐0313).