bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estradiol increases the density and open probability of epithelial sodium channels in alveolar cells
Authors: Greenlee Megan M , Duke Billie Jeanne , Eaton Douglas C 
Published: June 2021

Female sex hormones stimulate the expression of the lung epithelial sodium channel (ENaC); however, the effect of female sex hormones on channel number (N) and open probability (Po) has not been examined. We hypothesized that ENaC activity (NPo) will increase in lung alveolar cells treated with β‐estradiol and progesterone. Rat L2 alveolar‐type II‐like cells were cultured on transwells with apical air interfaces and steroid‐free basolateral media supplemented with vehicle (0.02% ethanol), β‐estradiol (200 pg/mL), progesterone (20 ng/mL), or a combination (200 pg/mL β‐estradiol and 10 ng/mL progesterone). We used cell‐attached patch clamp to measure ENaC NPo 18–28 hours after treatment. Combined hormone treatment increased the number of patches with channels from 38% to 88% (n=8, P<0.05) and increased ENaC NPo from 0.011 ± 0.008 to 0.47 ± 0.22 (n=8, P<0.01). The channel mean open time increased from 20 ± 2.5 ms (vehicle) to 73 ± 30 ms with hormone treatment (n=3–7, P<0.05). β‐estradiol alone activated ENaC (NPo=0.31 ± 0.18); progesterone alone did not (NPo= 0.001 ± 0.001). These results show that β‐estradiol stimulates ENaC activity in alveolar cells. Considering recent data showing greater ENaC activity in lungs from CFTR‐null mice, these results may have important implications for female cystic fibrosis patients at the onset of puberty.Funding: NIH 5R37DK037963‐25 and 5K12GM000680‐12 to DCE
The effect of nitric oxide on the detection of superoxide generated by mouse skeletal muscle fibres in vitro
Authors: Pearson Tim , Jackson Malcolm J 
Published: June 2021

Superoxide is generated from several pathways within muscle cells, including NADPH oxidase and the mitochondrial electron transport chain. Muscle derived superoxide has been claimed to exert multiple effects on muscle fibres including influencing force production, adaptive responses to contractions and in excess contributes to loss of function and cell death.Muscle superoxide activities were examined in single isolated fibres from the flexor digitorum brevis muscles of C57Bl6 mice using fluorescent confocal microscopy. Fibres were loaded with either dihydroethidium (5μM) or MitoSox Red (125nM) to determine cytoplasmic or mitochondrial superoxide respectively whilst in the presence or absence of L‐NAME (100μM), a nitric oxide synthase inhibitor. Images were acquired using Ex405 and Em605/15nm from fibres either at rest or subjected to two 9 minute contraction protocols at ten and forty minutes.2‐hydroxyethidium fluorescence increased acutely by 20–25% (1st, P<0.02) and 17–26% (2nd, P<0.001) after the first and second contraction period compared with fibres at rest (n=8) in both the presence and absence of L‐NAME. In contrast, the presence of L ‐ NAME significantly increased MitoSox fluorescence as compared with untreated fibres. The pattern of fluorophore oxidation argued that the contraction‐induced increase in cytoplasmic superoxide was not due to release from the mitochondria.Supported by MRC.
Thermal prolongation of the Hering‐Breuer inflation reflex in neonatal rats depends on an adenosinergic mechanism in the brainstem
Authors: Arnal Ashley V. , Gore Julie L. , Bartlett Donald , Leiter J. C. 
Published: June 2021

The Hering‐Breuer (HB) inflation reflex prolongs expiratory duration (TE), and elevated body temperature increases this prolongation in neonatal rats. The neurophysiological mechanisms of this thermal sensitivity have not been studied, but the thermal sensitivity of the HB reflex is similar to that of the laryngeal chemoreflex (LCR). Therefore, we tested the hypothesis that blocking adenosine receptors with caffeine, which shortens the LCR, would blunt the thermal prolongation of apnea associated with the HB reflex. Neonatal rats (P4 to P20) were anesthetized briefly to administer intracisternal caffeine (2 microL of 10 mM) or vehicle, allowed to wake up and studied in a head out plethysmograph. The HB reflex was elicited at body temperatures of 32 and 36 degrees C by decreasing the plethysmographic pressure (−5 cm H2O) at the end of inspiration. The inflation was maintained until the next inspiratory effort, and we measured the apneic interval between inspiratory efforts. Intracisternal injection of caffeine shortened the HB reflex apnea at the higher body temperature, and the shortening was greater in younger animals.Support: grants 36379 & 42707 from the NICHD.
The effects of chronic nicotine exposure on chemosensitivity of medullary 5‐HT neurons
Authors: Avraam Joanne , Wu Yuanming , Richerson George B 
Published: June 2021

5‐HT neurons are chemoreceptive and involved in respiratory control. SIDS has been linked to brainstem 5‐HT abnormalities, fetal nicotine exposure and impaired responses to changes in O2 and CO2. We tested the hypothesis that nicotine may increase the risk of SIDS by impairing 5‐HT neuronal function. We used perforated patch clamp to record changes in firing rate (FR) in response to acidosis and to acute nicotine exposure of 5‐HT neurons cultured for >12 days from the medullary raphé of 2 day old mice. An osmotic minipump was implanted into pregnant mice at E10 supplying 6 or 60 mg kg−1 day−1 of nicotine, and/or nicotine was subsequently added to the cultures at 0.05 μM or 0.5 μM respectively. Neurons were bathed in aCSF at 5% CO2 (pH 7.4) containing GABA and glutamate receptor blockers until FR stabilized at 1 Hz, then were exposed to two‐ 3 min episodes of 9% CO2 (pH 7.2) with wash out each time. This was then repeated with aCSF containing 10μM nicotine.Neurons exposed chronically to nicotine (n=92) exhibited a reduced response to acute nicotine exposure and to acidosis. These effects were found to be attributed to both prenatal and postnatal exposure and were more pronounced in mature neurons and in neurons exposed to a higher dose of nicotine. In the developing neonate such changes in 5‐HT neuronal function and chemoreception may impair responses to changes in O2 and CO2 and potentially increase the incidence of SIDS.
Paradoxical relationship between alpha‐adrenergic tone and muscle sympathetic nerve activity in human metabolic syndrome
Authors: Mckenna Edward Joseph , Limberg Jacqueline , Sebranek Joshua , Walker Benjamin , Hagen Scott , Morgan Barbara , Schrage William 
Published: June 2021

Animal models of metabolic syndrome (MS) exhibit greater basal adrenergic tone that may contribute to impaired blood flow. We hypothesized humans with MS would exhibit greater α‐adrenergic tone that correlated with higher muscle sympathetic nerve activity (mSNA). Phentolamine (PH, α‐adrenergic antagonist) was infused intra‐arterially into the forearm of MS adults (n=11) and healthy controls (n=16). mSNA was measured (microneurography) in a subset of subjects (n=15). Forearm blood flow (Doppler ultrasound) was normalized for higher blood pressure (BP) in MS and relative changes in vascular conductance (VC = blood flow/BP) were assessed. VC increased with PH infusion similarly between groups. MS exhibited greater mSNA compared to controls (66±9 vs 35±4 bursts/100 heart beats, p<0.01). Greater α‐adrenergic tone was inversely related to mSNA (r = 0.5, p= 0.07), thus adults with higher mSNA had less increase in VC with PH infusion. In summary, despite higher mSNA, adults with MS do not exhibit greater α‐adrenergic tone. These results suggest physiological adaptations occur with higher mSNA that blunt sympathetically‐mediated vasoconstriction at rest. This may be due to reduced adrenergic responsiveness or norepinephrine release.Support: AHA 10PRE3870000, NIH HL091397, APS Summer Undergraduate Research Fellowship.
Carotid baroreflex control of blood pressure to simulated hypotension in young and older women
Authors: Kim Areum , Fisher James P , Fadel Paul J 
Published: June 2021

Limited studies have examined the influence of aging on cardiovascular control in women. The arterial baroreflex plays a critical role in beat‐to‐beat regulation of arterial blood pressure (BP). However, the effect of aging on baroreflex control in women remains incompletely understood. Thus, we examined baroreflex control of BP, heart rate (HR), and muscle sympathetic nerve activity (MSNA) in 9 young (YW, 22±1 yr) and 8 older (OW, 62±2 yr) women using 5s pulses of neck pressure (+40 Torr) to simulate carotid sinus hypotension. Mean BP and MSNA burst frequency and incidence were higher at rest in OW compared to YW (P<0.05). In response to neck pressure, OW exhibited attenuated BP (+14±2 YW vs. +6±1 OW %baseline; P<0.05) and HR (+18±3 YW vs. +5±1 OW %baseline; P<0.05) responses. In contrast, increases in total MSNA to neck pressure were similar between groups (+88±26 YW vs. +95±20 OW %baseline; P>0.05). Our preliminary findings suggest that older women exhibit blunted pressor responses to carotid hypotension. These attenuated BP responses do not seem to be explained by an impairment in baroreflex control of MSNA, but may be related to reduced cardiac responsiveness. However, a potential alteration in the vascular response to increases in MSNA between young and older women requires investigation.Supported by R01HL093167
Macrophage inhibitory factor (MIF) in the nucleus of tract solitary (NTS) improves baroreflex function in spontaneously hypertensive rats (SHR)
Authors: Freiria-Oliveira Andre H. , Blanch Graziela T. , Li Hongwei , Colombari Debora S. A. , Sumners Colin , Colombari Eduardo 
Published: June 2021

SHR have impaired baroreflex function. Previously we demonstrated that increased expression of MIF in the NTS of SHR can reduce resting mean arterial pressure (MAP). Thus, in this study we investigated whether MIF over expression in the NTS of SHR can alter baroreflex function. Male SHR (9 weeks old) or normotensive (NT) control rats were injected at 5 sites in the NTS with (1×109 gc in 150 nl) adenoassociated viruses for over expression of MIF or eGFP. Thirty days after the microinjections the femoral artery and vein were cannulated under anesthesia to measure MAP and heart rate (HR), and to perform drug infusions in awake animals the next day. During the experiment, we used phenylephrine to elicit a pressor response (5 μg/kg) and sodium nitroprusside (30 μg/kg) to produce a depressor response, and analyzed the HR reflex response to each 10 mmHg change in MAP. The results showed that the SHR‐eGFP group exhibited a significant impairment of the baroreflex compared with the NT‐eGFP rats, as expected. Further, the SHR‐MIF rats exhibited improvement in the baroreflex curves as to tachycardia (1/slope: − 2.4 ± 0.38) and bradycardia responses (1/slope: −3 ± 0.28) when compared to SHR‐eGFP rats (1/slope bradycardia: −1.1 ± 0.28; tachycardia: −1.2 ± 0.72). The results showed that MIF over expression in the NTS improves the cardiac baroreflex in SHR, helping to decrease the MAP in these animals.Supported by: CNPq, FAPESP, NIH
Metabolic and cardiovascular effects of AT1 receptor blockade in rats with diet‐induced obesity
Authors: Junior Silvio Assis Oliveira , Guizoni Daniele Mendes , Martinez Paula Felippe , Torres Bárbara Pereira , Campana Alvaro Oscar , Padovani Carlos Roberto , Okoshi Katashi , Okoshi Marina Politi , Cicogna Antonio Carlos 
Published: June 2021

Causes of metabolic and cardiovascular disturbances in obesity are poorly understood. This study analyzed whether the angiotensin II receptor blockade reverses abnormalities in diet‐induced obesity. Wistar‐Kyoto rats (n=40) were subjected to control (C) or hypercaloric diet (OB) for 30 weeks and then assigned to four groups: C, C+Los, OB, and OB+Los. Los‐groups received losartan (30mg/kg/day) during five weeks. Subsequently, cardiac structures and function were assessed by echocardiography. Glycemia was studied by tolerance glycemic curve. OB‐groups presented higher body mass and adiposity. Other results are in the table.ConclusionLosartan improves metabolic and cardiovascular profile in diet‐induced obesity.
Strain‐dependent variation in vasoreactivity in isolated mouse thoracic aorta
Authors: Kim Seung Kyum , Avila Joshua J. , Massett Michael P. 
Published: June 2021

Understanding genetic influence on vascular reactivity is important for identifying genes underlying impaired vascular function. Therefore, the aim of this study was to characterize genetic variation in vascular reactivity using 14 inbred strains of mice. Concentration response curves to phenylephrine (PE), potassium chloride (KCl), acetylcholine (ACh), and sodium nitroprusside (SNP) were obtained from aortic rings from male mice (n ≈ 4/strain). Contractile responses to PE and KCl varied significantly across strains. In response to PE, aorta from PWD/PhJ had the lowest (43.8 ± 6.7 %) and aorta from NZW/LacJ had the highest (160.8 ± 15.6 %) maximal response. Aorta from C57BL/6J and 129S1/SvImJ had the lowest (112.0 ± 19.8 %) and the highest (183.2 ± 5.5 %) maximal response to KCl, respectively. Endothelium‐dependent relaxation responses to ACh were also significantly different across strains with NZW/LacJ having the lowest (50.1 ± 7.7 %) and C3H/HeJ having the highest (98.6 ± 0.5 %) maximal response. Maximal endothelium‐independent relaxation responses to SNP were similar among strains. Differences in sensitivity to all agents were observed across strains. These data demonstrate that there are large strain‐dependent differences in vasoreactivity across inbred mouse strains and indicates that genetic background influences vascular function.Supported by NIH grant HL085918 to MPM
Impact of Antenatal Betamethasone (B) on p47 phox in Kidney and 8‐isoprostane Responses to Angiotensin II in Proximal Tubule Cells in Male Sheep after Uninephrectomy
Authors: Bi Jianli , Su Yixin , Figueroa Jorge , Chappell Mark C. , Rose James C. 
Published: June 2021

Antenatal B administration reduces nephron number and causes hypertension in offspring. It is not clear if antenatal B enhances responses to a second insult (additional loss of nephrons).This study examined if antenatal betamethasone exposure increases susceptibility to a second “hit”. Adult male sheep exposed to B or Vehicle (V) (n=3–6) before birth underwent uninephrectomy (UN). Necropsy was performed 15 days after UN. Renal cortex was collected at both times. PTCs from both kidneys were stimulated with Ang II with or without its antagonists. P47 expression was determined by western blotting and 8‐PGF in media was measured by ELISA. Data were analyzed by ANOVA or T‐test.B exposure increased p47 expression (p<0.05) in kidneys obtained at uninephrectomy (first kidney) and at necropsy (second kidney) (B sheep vs. V sheep F=16, P=0.007). UN increased p47 in the second kidney in both groups (F=6.5, p=0.043). The highest expression of p47 was in the second kidney from the B exposed animals.Ang II stimulated 8‐PGF secretion from PTCs of the kidneys from B exposed sheep only (F=8.4, P=0.009 first kidney) and (F=5.5, P=0.044 second kidney). The response was blocked by candesartan but not PD123319. Ang II increased 8‐PGF secretion the most in PTCs from second kidney of B exposed animals (p<0.05).This suggests antenatal B exposure predisposes the kidney to oxidative stress from a“second hit”. Supported by HD‐47584 and HD‐17644
Simulated microgravity modifies intestinal epithelial barrier function and alters expression of tight junction proteins
Authors: Stork Cheryl Anne , Marchelletta Ronald R. , Prisk G. Kim , McCole Declan F. 
Published: June 2021

The integrity of the intestinal epithelial barrier is tight junctiondependent. Previous studies showed that exposure to microgravity compromises the human immune system and increases enteropathogen virulence. However, the effects of microgravity on epithelial barrier function are unknown. Here, we investigated the effects of simulated microgravity on HT‐29 intestinal epithelial cell (IEC) barrier properties. IECs were (i) cultured on microcarrier beads for 18 days while subjected to simulated microgravity in a rotating wall vessel (RWV); (ii) cultured on beads for 18 days in culture plates (static control); (iii) grown in flasks for 18 days (flask control); prior to seeding on inserts. RWV cells displayed reduced transepithelial resistance (TER) on days 2–14 after seeding (−6 ± 3% vs. static day 11; n=4). Confocal analysis revealed increased expression of tight junction proteins Zonula Occludens‐1 (ZO‐1) and Occludin in RWV cells over 2–14 days (ZO‐1: 59–66 ± 11 pixels/unit area; n=3–4) vs. static (40–56 ± 10 p/ua) and flask (38–46 ± 10 p/ua) controls. Moreover, RWV cells showed delayed localization of Occludin and ZO‐1 to the apical junctions suggesting altered intracellular trafficking. In conclusion, cells exposed to simulated microgravity exhibit reduced TER and altered expression and distribution of tight junction proteins suggestive of a functional barrier defect.Supported by NIH UH2 AA019708‐01.
Endothelins induce choleresis through ETB receptors coupled to nitric oxide release and vago‐vagal reflexes
Authors: RODRIGUEZ MYRIAN ROXANA , Ventimiglia María Silvia , Najenson Ana Clara , Vatta Marcelo Sergio , Bianciotti Liliana Graciela 
Published: June 2021

We previously showed that brain applied ET‐1 and ET‐3 in rats induce choleresis or cholestasis depending on the dose. In this study we evaluated if endothelins (ETs) regulated bile secretion when peripherally infused. Animals were prepared with jugular vein and bile duct cannulation to infuse drugs and collect bile samples. At the doses used ETs did not affect hepatic blood flow or portal venous pressure. ETs induced significant choleresis, being ET‐1 more potent than ET‐3. ETs increased bile salts, electrolytes and glutathione excretion supporting enhanced bile acid dependent and independent flows. ETs‐induced choleresis was mediated by ETB receptors coupled to nitric oxide and abolished by truncal vagotomy or capsaicin perivagal application. RT‐PCR and western blot analysis showed ETA and ETB receptor expression in the vagus nerve. ETs through ETB stimulated sodium taurocholate co transporter polypeptide (Ntcp) and aquaporin 8 (AQP8) translocation to the plasma membrane and augmented Ntcp, AQP8, bile salt export pump (Bsep) and multidrug resistance protein 2 (Mrp2) in microsomal membranes. Real time PCR studies showed that exposure to ETs increased the mRNAs of these transporters. ETs induced choleresis through ETB receptors coupled to nitric oxide and vago‐vagal reflexes without involving hemodynamic changes. These findings suggest that ETs may play a beneficial role when bile secretion is impaired.(CONICET PIP 0370/ ANPCyT‐PICT2008‐0716)
The mechanism of the marine thromboxane B2 inhibitor Manzamine A: possible involvement of rat brain microglia p90 ribosomal S6 kinase 1
Authors: Clifford Jonathan A , Lach Joseph , Hall Mary L , Mayer Alejandro M 
Published: June 2021

Manzamine A (MZA) potently inhibited LPS‐activated rat microglia (BMΦ) TXB2 (IC50<0.016 μM) and O2− (IC50=0.1 μM) generation, (BMC Pharmacology 5(1)6, 2005), as well as LPS‐activated human BMΦ TXB2 (apparent IC50<0.7 μM) (Inflam Res. 53(S3): S217, 2004). We have shown that MZA selectively inhibited rat p90 ribosomal S6 kinase 1 or RSK1 (IC50=15.01 μM) vs human RSK2 (IC50=108.4 μM) (Program 545.5, Society of Neuroscience, 2009). We hypothesized that TXB2 inhibition by MZA in BMΦ involved RSK1 inhibition. In order to test our hypothesis we first investigated the presence of RSK1 and RSK2 proteins in rat BMΦ. Briefly, we prepared protein extracts from untreated, LPS (0.3 ng/mL)‐treated, and LPS + PMA (1μM)‐ treated BMΦ, and probed by western blot analysis using RSK1 (Cell Signaling) and (phosphorylated RSK1) pRSK1 (Epitomics) antibodies.Results1) RSK1 and RSK2 proteins were present in similar quantity in all BMΦ extracts tested; 2) PMA enhanced pRSK1 protein in LPS‐treated BMΦ. Thus because RSK1, RSK2, and pRSK1 proteins are present in rat microglia they may be involved in TXB2 inhibition by MZA. We conclude that in order to test this hypothesis, the concentration‐dependent effect of MZA on BMΦ RSK1 phosphorylation and concomitant TXB2 inhibition will require further investigation. Support to JC and JL by the Student Fellowship Program, Office of Research, Midwestern University is gratefully acknowledged.
Leptin activates rat carotid body Type I cells and brainstem astroglial cells
Authors: Marina Nephtali , Kasymov Vitaliy , Mohamed-Ali Vidya , Kasparov Sergey , Gourine Alexander V 
Published: June 2021

Obesity is strongly associated with significant increases in muscle vasoconstrictor sympathetic activity which may contribute to the development of obesity‐related hypertension. Sympathetic tone and blood pressure can be reflexly increased by activation of peripheral chemoreceptors in the Carotid Bodies. Similarly, we have recently shown that optogenetic activation of ventral medullary astrocytes results in sympathoexcitation and increases in blood pressure. Leptin and leptin receptors have been recently found to be expressed both in Carotid Body Type I cells and in astroglial cells. Here, we explored whether these receptors are functional and whether leptin is capable of triggering activation of Carotid Body Type I cells and brainstem astroglial cells in vitro.RESULTSIn Carotid Body dissociated cultures and primary cultured brainstem astrocytes loaded with Ca2+ indicator Fura‐2, application of recombinant rat leptin evoked dose‐dependent increase in [Ca2+]i. The responses had long latency (approximately 500 sec.) and [Ca2+]i oscillations were sustained for prolonged periods.CONCLUSIONSThese data suggest that sustained high levels of circulating leptin in obesity have the potential to activate Carotid Body Type I cells and brainstem astroglial cells, leading to increases in sympathetic tone and blood pressure.
G‐protein Coupled Receptor 30 (GPR30) in the Human Endothelium: New Roles for a Novel Estrogen Receptor
Authors: Chakrabarti Subhadeep , Davidge Sandra T 
Published: June 2021

Estrogen is a modulator of endothelial function. Traditionally the effects of estrogen were believed to be mediated through its classical receptors alone. There is increasing evidence of a novel G‐protein coupled receptor GPR30 in mediating some estrogenic actions. While there is evidence of vascular actions of GPR30, this protein has not been identified to date in the human endothelium and its endothelium‐specific roles are poorly understood. We used human umbilical vein endothelial cells (HUVECs) as a model system. A specific pharmacological agonist (G‐1) and an antagonist (G‐15) were used to characterize roles of GPR30. Inflammatory changes were induced by stimulation with the pro‐inflammatory cytokine tumor necrosis factor (TNF). NF‐kappaB activation was determined by degradation of inhibitor kappaB and nuclear translocation of p65. We detected GPR30 protein in HUVECs by both western blotting and immunofluorescence. GPR30 activation by G‐1 increased F‐actin and stress fibre formation in HUVECs which were prevented by G‐15 administration. G‐1 treatment also inhibited TNF‐mediated adhesion molecule expression in these cells, without altering NF‐kappaB activity. Our results suggest that endothelial GPR30 is a novel mediator of actin polymerization and anti‐inflammatory effects downstream of NF‐kappaB.This work was supported by CIHR.