bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of TMEM16A Expression on Motility and Metastasis in Epithelial Tumor Cells
Authors: Shiwarski Daniel John , He Lu Mei , Huang Xin , Gollin Suzanne , Grandis Jennifer , Duvvuri Umamaheswar
Published: June 2021

TMEM16A, a novel gene that regulates Ca+‐activated Cl− currents, was recently isolated from oral cavity cancer cells. TMEM16A is overexpressed in several tumor types; however, the role that TMEM16A plays in promoting tumor motility remains unclear. The goal of this project was to characterize the role of TMEM16A in cancer cell motility, invasion, and metastasis. We hypothesized that TMEM16A contributed to tumor cell motility and may be an important factor in metastasis through epithelial to mesenchymal transition (EMT) in cancer. SCCHN and T24 bladder cancer cell lines were transduced with lentiviral particles encoding RNAi against TMEM16A, and stable cell lines overexpressing TMEM16A were also created. To assess motility we used trans‐well migration and scratch assays with agonists and inhibitors of TMEM16A. As hypothesized, overexpression of TMEM16A decreased motility and these results were confirmed using a dominant inactive construct. We further evaluated TMEM16A levels in primary and metastatic cell lines. Metastatic lines had reduced TMEM16A levels compared to paired primary cell lines. In summary, our results provide novel insights into the biologic function of TMEM16A in tumor motility and metastasis. This research has significantly enhanced our understanding about the pathogenesis of epithelial tumors, and can potentially be translated to many cancer types.

Funded by:

SPORE H&N Career Development Award (U.D.)

Department of Otolaryngology Startup Funds (U.D.)

SPORE H&N P50 CA 0A097190
Vasopressin independent trafficking of aquaporin‐2 by prostaglandin E2
Authors: Olesen Emma Tina Bisgaard , Moeller Hanne Bjerregaard , Nielsen Søren , Frøkiær Jørgen , Praetorius Helle A. , Fenton Robert Andrew
Published: June 2021

Trafficking of aquaporin‐2 (AQP2) to the apical plasma membrane (APM) of principal cells in the renal collecting duct is predominantly regulated by vasopressin (VP). We investigated whether prostaglandin E2 (PGE2) could regulate AQP2 trafficking via an alternative VP independent mechanism. In vitro studies were performed using MDCK cells stably transfected with either wild type AQP2 (WT) or a mutated form where serine‐256 is substituted with alanine (S256A) and therefore cannot be phosphorylated. To analyze APM abundance of AQP2 we used both a biochemical approach based on biotin cell surface protein labeling and immunocytochemistry. Compared to controls, 40 minutes of PGE2 (10−7M) increased APM abundance of AQP2 in WT cells, but not in S256A cells. Varying PGE2 concentrations, from 10−10M to 10−6M, resulted in a gradual increase in AQP2 APM abundance. A time course study of PGE2 stimulation for 5 to 120 minutes revealed that APM abundance of AQP2 increased until 80 minutes and that this effect was sustained at 120 minutes. AQP2 S256 phosphorylation increased after 40 min of PGE2 stimulation. The prostanoid receptor 4 (EP4) antagonist AH23848, 30μM, attenuated, but did not completely abolish the effect of PGE2 on AQP2 trafficking. We conclude that PGE2 induces trafficking and S256 phosphorylation of AQP2 and that trafficking may be mediated, at least in part, by the EP4 receptor.
Insulin stimulation of the epithelial sodium channel is inhibited by COMMD1
Authors: McDonald Fiona Jean , Swart Marianne , Ke Ying
Published: June 2021

The epithelial sodium channel (ENaC) transports Na+ into epithelial cells located in the distal nephron, lung, and colon. Active channel number at the cell surface is regulated by ubiquitin modification and endocytosis. Insulin, aldosterone and vasopressin enhance Na+ transport via the serum and glucocorticoid regulated kinase (SGK1) that inactivates the ubiquitin ligase Nedd4‐2 that downregulates ENaC. Previously we reported that COMMD1 (copper metabolism Murr1 domain containing protein 1) inhibits ENaC amiloride‐sensitive current. Here the objective was to determine if COMMD1 and ENaC are coexpressed in kidney, and to study the mechanism by which COMMD1 inhibits ENaC amiloride‐sensitive current. Using immunohistochemistry COMMD1 was found to be widely expressed in the kidney, and to co‐localise with ENaC. Biochemical and electrophysiological assays showed that COMMD1 increased ubiquitin modification of ENaC and decreased its cell surface expression. COMMD1 abolished insulin‐stimulated amiloride‐sensitive current. COMMD1 co‐immunoprecipitated with SGK1 and Akt1, but not Nedd4‐2. Knock‐down of COMMD1 enhanced the effect of SGK1 and Akt1 on amiloride‐sensitive current, but did not change the effect of Nedd4‐2. In conclusion, COMMD1 regulates ENaC cell surface expression via Nedd4‐2.

Support from the Marsden Fund Council from Government funding administered by the Royal Society of New Zealand
Regulation of ENaC by the Cytoskeleton
Authors: Reifenberger Matthew S , Duke B.J , Yu Ling , Eaton Douglas
Published: June 2021

The cytoskeleton is increasingly being recognized for its role in regulating either directly or indirectly membrane organization and signaling pathways. The role the cytoskeleton plays in regulating Epithelial Sodium Channel (ENaC) function, and the mechanisms involved, remain unclear. ENaCs are located in the collecting tubule of the kidney where they facilitate reabsorption of the final 1–3% of the filtered sodium load. The object of this study was to determine the effect of cytoskeleton disruption on ENaC activity and the mechanisms involved. Single channel ENaC activity was recorded from amphibian distal nephron 2F3 cells using a cell‐attached patch clamp configuration. Treatment with 0.75 mg/mL cytochalasin E (Cyto E), an inhibitor of actin polymerization, for 30 – 120 min decreased the likelihood of finding patches with ENaC activity. In non‐treated cells 8 out of 33 patches (24%) did not contain ENaC activity while in treated cells 17 out of 32 patches (53%) did not contain activity. Analysis of those patches that did contain ENaC activity showed channel open probability significantly decreased from 0.081 ± 0.01 in non‐treated cells to 0.043 ± 0.01 in cells treated with Cyto E. Confocal images of 2F3 cells stained with Alexa Fluor 568 Phallodin confirmed significant cytoskeletal disruption with cyto E, however preliminary evidence suggest ENaC localization was not drastically altered with cyto E treatment.
Protease activated receptor‐2 (PAR‐2) in the airway epithelium: a sentinel receptor triggered by the asthma associated allergen Alternaria alternata
Authors: Flynn Andrea N , Vagner Josef , Schulz Stephanie , Hoffman Justin , Boitano Scott
Published: June 2021

In semi‐arid regions allergic asthma is strongly associated with the ubiquitous fungus Alternaria alternata. Similar to other allergens that trigger asthma, Alternaria has protease activity that can directly cleave and activate the G‐protein coupled receptor PAR‐2 in the airway epithelium. Using ratiometric Ca2+ imaging, we found Alternaria filtrate (3.52 μg/ml protein; 0.58 μg/ml protease activity) lead to a rapid increase in intracellular Ca2+ concentration ([Ca2+]i) in a human bronchial epithelial cell line. Consistent with PAR‐2 activation, Alternaria‐dependent [Ca2+]i changes were ablated by heat inactivation of the filtrate or pretreatment with serine‐specific protease inhibitors. While Alternaria filtrate did not activate HeLa cells with minimal PAR‐2 expression, HeLa cells transfected with PAR‐2 responded to Alternaria by increasing [Ca2+]i. PAR‐2 can also be activated without proteolytic cleavage by small peptides (e.g., SLIGRL) and peptidomimetic compounds (e.g., 2‐furoyl‐LIGRL). We have developed two novel peptidomimetic compounds; a DTPA/Europium‐tagged ligand that allows for direct biochemical analysis of PAR‐2, and an LIGRL‐based compound that is predicted to improve in vivo stability. Further investigation of these and other novel ligands is central to understanding the role of PAR‐2 and may aid the development of treatments for allergic asthma.
MICRORNA‐150 REGULATES SURFACTANT SECRETION VIA P2X7 RECEPTORS
Authors: Weng Tingting , Mishra Amarjit , Guo Yujie , Wang Yang , Su Lijing , Liu Lin
Published: June 2021

P2X7 receptor (P2X7R) is a purinergic ion‐channel receptor. Previously, we found that the activation of P2X7R in alveolar type I cells could activate the surfactant secretion in alveolar epithelial type II cells. In this study, we determined whether miRNAs regulate P2X7R‐mediated surfactant secretion. We first used a dual‐luciferase assay to screen the regulation of P2X7R 3′‐UTR activity by miR‐150, miR‐186, miR‐204 and miR‐211. We found that miR‐150 is a regulator of P2X7R in lung epithelial cells. The miR‐150 regulation could be disrupted by site mutation of mature miR‐150 or mutation of P2X7R 3′‐UTR at miR‐150 binding sites. MiR‐150 expression level in alveolar type II cells was much higher than alveolar type I cells, which was inversely correlated with the P2X7R protein level. Adenovirus expressing miR‐150 significantly downregulated the P2X7R protein expression in E10 cells. Furthermore, pre‐treatment of E10 cells with adenovirus expressing miR‐150 disrupted the surfactant secretion stimulated by E10 cell conditioned media. Our study is the first of its kind to demonstrate that miR‐150 regulates P2X7R mediated surfactant secretion (supported by NIH grants R01 HL‐083188).
Chronic ethanol exposure disrupts neuroventilation and responses to hypoxia in bullfrog tadpoles
Authors: McLane Lisa H , Brundage Cord M , Taylor Barbara E
Published: June 2021

Chronic early developmental ethanol (EtOH) exposure is a sudden infant death syndrome risk factor and impairs neonatal rat hypoxic ventilatory responses. 10‐wk EtOH exposure impairs tadpole CO2 ventilatory responses. We hypothesized that tadpole hypoxic ventilatory responses would be impaired by EtOH. Neurocorrelates of lung and gill ventilation were recorded from in vitro brainstems of control and 10‐wk EtOH‐exposed tadpoles during normoxia and hypoxia. The tadpole central hypoxic ventilatory response was a reduced lung burst frequency and an increased lung burst duration, and these responses became more pronounced over development. Early‐stage tadpoles also increased gill burst amplitude late in hypoxia. 10‐wk EtOH exposure depressed baseline lung burst frequency and the hypoxia‐induced changes in lung burst duration and gill burst amplitude. Across development, chronic EtOH destabilized neuroventilation. The more marked impairments in late‐stage tadpoles suggest developmentally increased EtOH sensitivity or a disrupted maturation of the hypoxic ventilatory response. Thus, the ventilatory consequences of developmental EtOH exposure are an impaired hypoxic and hypercapnic responses.
Suppression of expiratory activity in a mouse model of Rett Syndrome follows blockade of GABA reuptake and activation of serotonin type 1a receptors
Authors: Abdala Ana Paula Lima , Dutschmann Mathias , Bissonnette John M. , Paton Julian F.R.
Published: June 2021

Rett Syndrome (RTT) is a neurodevelopmental disorder that features frequent apneic episodes. The MeCP2+/− mouse is a model of RTT and mimics these respiratory abnormalities. We have shown in an in situ preparation that tonic bursting in the expiratory portion of hypoglossal (HN) and abdominal (AbN) nerves characterize these apneas. In order to strengthen the hypothesis that insufficient inhibition of expiratory neurons underlies phrenic (PN) apnea, we examined HN burst envelope in the apneas that remained after GABA reuptake was blocked (NO‐711, 5.2μM). GABA uptake block reduced tonic HN by 24±3 % in MeCP2+/− females. In addition, tonic AbN was eliminated in mice that showed this before NO‐711. The combination of GABA reuptake blockade and 8‐OH‐DPAT (a 5‐HT1a agonist) abolished apneas completely precluding examination of the effect on HN and AbN. We propose that aberrant expiratory discharges may explain the apneas and that NO‐711 and 8‐OH‐DPAT act synergistically to suppress this excessive expiratory activity in the brainstem respiratory network, thereby correcting the respiratory phenotype observed in MeCP2+/− mice. Supported by NIH R01 NS057815; MOD; IRSF.
Gas bubble composition does not affect the detection of exercise‐induced intrapulmonary arteriovenous shunt in hypoxia, normoxia or hyperoxia
Authors: Elliott Jonathan E , Choi Yujung , Laurie Steven S , Yang Ximeng , Gladstone Igor M , Lovering Andrew T
Published: June 2021

Concern has been raised that altering the fraction of inspired O2 (FIO2) could accelerate or decelerate microbubble dissolution time within the pulmonary vasculature and thereby invalidate the ability of saline contrast echocardiography to detect IPAV shunt. The current study determined if the gaseous component used for saline contrast echocardiography affects the detection of exercise‐induced IPAV shunt under varying FIO2's. Eleven healthy subjects (6 female) performed three, 11 min bouts of cycle ergometer exercise at 60% VO2max, in hyperoxia (FIO2 = 1.0), normoxia (FIO2 = 0.21) and hypoxia (FIO2 = 0.14). Five different gases were used to create saline contrast bubbles and were injected in the following order at 2 min intervals: room air, 100% N2, 100% O2, 100% CO2 and 100% He. During exercise, for any FIO2, there was no significant difference in shunt score when using the different bubble gas compositions. Breathing hyperoxia prevented exercise‐induced IPAV shunt whereas breathing hypoxia and normoxia resulted in a significant level of exercise‐induced IPAV shunt. The current results support our previous work and validate the use of room air as the gaseous component of saline contrast bubbles to detect IPAV pathways during exercise in any FIO2. These results call into question the validity of the 100% O2 technique to detect and quantify right‐to‐left shunting via inducible IPAV pathways. Funding: OHSU MRF 0820
Denitrogenation (Preoxygenation) as a Prophylactic Treatment for “Flier's Bends” During High Altitude Missions in Unpressurized Aircraft of the Allied Air Forces in World War II
Authors: Dean Jay B.
Published: June 2021

Allied aviators flew missions in unpressurized planes to 20,000–30,000 feet and avoided hypoxia by using demand O2 equipment. With the advent of pressure demand O2 equipment, the pilot's ceiling was raised to 35,000–47,000 feet! Any mission flown above 20,000 feet increased their risk for decompression sickness (DCS); that is, gases dissolved in their tissues at sea level air pressure would come out of solution at hypobaric pressure to form bubbles (mostly N2) causing pain in the extremities and, in the worse cases, paralysis or death. DCS (aka “Caisson's disease/Diver's bends”) had long been recognized as a serious problem for men who decompressed too quickly from hyperbaric air pressure. “Flier's bends”, however, would not be appreciated until aeronautical engineering developed aircraft capable of flight above 20,000 feet, which finally occurred in the 1930s. Beginning in 1934, Harry Armstrong (Wright Field) would reveal that DCS occurred in men and animals during high altitude “chamber flights”. Armstrong showed in 1940 that 30 min of breathing pure O2 before ascending to altitude (preoxygenation) reduced both the level of N2 in the body (denitrogenation) and the risk of DCS. Breathing O2 for 30–40 min before flight or during ascent to 20,000 feet became standard operating procedure for high altitude missions in WWII. Today, astronauts use preoxygenation prior to extravehicular activity to reduce the risk of DCS.
Diet and exercise training reverses the vascular reactivity impairment of subjects with the 894G>T endothelial nitric oxide synthase gene polymorphism
Authors: Silva Bruno Moreira , Neves Fabricia J. , Sales Allan K. , Rocha Natalia G. , Medeiros Renata F. , Barbosa Thales C. , Pereira Felipe S. , Cardoso Fabiane T. , Nóbrega Antonio C. L.
Published: June 2021

The 894G>T endothelial nitric oxide synthase (eNOS) gene polymorphism has been shown to impair vascular function, but it is unknown whether it is reversible. Our aim was to investigate the influence of this polymorphism on the vascular reactivity adaptation to an intervention composed of diet and exercise training. We studied 34 healthy, sedentary, eumenorrheic women (age 32±9 year, BMI 24±3 kg/m2). Twenty had the polymorphic allele [GT (n=15) or TT (n=5) genotypes] and 14 did not (GG genotype). Before and after 12 weeks of intervention, the forearm vascular conductance (FVC) response to a 5 min vascular occlusion was assessed (plethysmography) before, 10, 60 and 120 min after a maximal treadmill test. The groups were similar for pre‐intervention anthropometric, metabolic and hemodynamic characteristics (p>0.05). Subjects with the polymorphism had lower FVC response at the 120 min measurement pre‐intervention (% change from pre‐ischemia, 322±39 vs. 427±49 %, p=0.05). The intervention improved anthropometric, metabolic and hemodynamic characteristics similarly in both groups (p<0.05). The FVC response to ischemia increased post‐intervention in both groups (p<0.05), and there was no difference between them anymore (p>0.05). In conclusion, diet and exercise training reversed the vascular reactivity impairment of subjects with the 894G>T eNOS gene polymorphism. Support: CAPES, CNPq, FINEP and FAPERJ.
Mouse strain dependent variation in exercise capacity
Authors: Courtney Sean Michael , Massett Michael P.
Published: June 2021

The aim of this study was to characterize differences in exercise capacity across mouse strains and estimate the genetic contribution to exercise performance. Male mice from 15 inbred strains (n=6/strain) performed a graded exercise test to exhaustion as a measure of exercise capacity. Significant differences were found across strains, with the A/J mice having the lowest (18.4 ± 0.29 minutes) and the AKR/J mice having the highest (43.5 ± 0.32 minutes) exercise capacity. To estimate running economy, VO2, VCO2 and respiratory exchange ratio (RER) were measured during a sub‐maximal treadmill test. Significant strain‐dependent differences were found for VO2, VCO2 and RER during sub‐maximal exercise. In addition, maximal running time was negatively correlated with RER (R2= −0.18, −0.19, −0.24) and positively correlated with VO2 (R2= 0.11, 0.12, 0.08) at speeds of 10, 15 and 20 m/min, respectively. Broad sense heritability was calculated for maximum run time, and VO2 and RER during sub‐maximal exercise. Heritability was ≥ 0.90 for maximum run time, 0.29 – 0.56 for sub‐maximal VO2 and 0.19 – 0.50 for sub‐maximal RER. These results indicate that exercise capacity and running economy are positively related and mouse strain‐dependent. Furthermore, heritability estimates suggest that the contribution of genetic background varies across measures of exercise capacity. Supported by NIH grant HL085918 to M. P. M.
Cortisol Level And Behavioral Response To Exercise In Dogs Kenneled In A Humane Society: Model For Stress Relief
Authors: Belpedio Camille , Buffington Laurie , Clusman Sarah , Prete Frederick , Sadler Aimee , Whittemore Lauren , Mungre Sue
Published: June 2021

Stress causes a major effect on several systems of the body, including cardiovascular, digestive and immune systems. Behavioral signs also reflect stressful condition. Exercise and a good social network are believed to lower stress. We used dogs kenneled in a humane society as a model to study the effect of exercise and socialization on stress‐related symptoms. We measured behavioral signs of stress including but not limited to scratching, distress whining and exaggerated grooming Research shows a relationship between stress and elevated cortisol levels. We measured salivary cortisol as a biochemical measure of stress. Dogs were allowed to acclimatize to shelter conditions. The experiment was conducted over four days with 40 dogs. The experimental group consisting of 20 dogs, were allowed to play and socialize for 30 minutes, whereas control dogs stayed in their kennels. Salivary cortisol and behavioral indices were measured before and after exercise play session. Dogs that played and had social contact showed less stressful behaviors as well as lower cortisol levels. Our studies suggest that physical activity and social contact alleviates stress.
The consequences of maternal training and detraining in adult offspring
Authors: Fernandes Leandro , Calegare Bruno FA , Tufik Sergio , D'Almeida Vania
Published: June 2021

Growing interest has been driven by the discovery of a tight relationship between prenatal manipulations and development of short‐ and long‐term health disorders. In the current investigation we tested how swimming training (T) (8 weeks, 5 times/week, 1 h/day) of female mice before fecundation affects the metabolic profile of their offspring. We also investigated detraining (DT) effects during pregnancy in a group of animals. Three groups of pups were formed: one which T was maintained during pregnancy (TP); other which mothers were submitted to DT during pregnancy (DTP) and; a control group (C) of no trained mothers. The offspring was weighted until the 3rd month of age, when female mice were euthanized, perigonadal adipose tissue was weighted and blood was collected to measure leptin and insulin. The results had been analyzed by ANOVA followed Tukey test (p≤0.05). Animals presented differences in body weight at the 3rd day of life (F(2, 145)=27.72), as well as, at post natal day 90 (F(2, 22)=9.12; DTP < DT and C). The TP group presented higher adipose tissue weight and plasma leptin levels than animals of DTP and C. Concerning insulin, a tendency of augmentation was observed on TP group. Our data suggest that physical activity or its interruption produce alterations on the intrauterine environmental which could result in long lasting offspring metabolic modifications. Support: FAPESP, CNPq and AFIP.
Dietary choline affects strength gains in elderly people
Authors: Lee Chang Woock , Lee Teak V. , Chen Vincent C.W. , Bui Steve , Riechman Steven E.
Published: June 2021

Background

Choline is a precursor to acetylcholine, which transmits neural signals to skeletal muscle. Thus, dietary choline may affect muscle contraction and exercise performance by mediating availability of acetylcholine at the neuromuscular junction. We examined the effects of choline consumption on muscle responses to resistance exercise training (RET) in the elderly.

Methods

Two groups of healthy untrained 50–69 year old men and women underwent 12 weeks of RET (3x/week, 3 sets, 8–12 reps, 70% of 1 Repetition Maximum (1RM)). Each group consumed <350 mg/day (Low, mean=210.1±20 mg/d, n=17) or >350 mg/day (Adequate, mean=461.7±19 mg/d, n=19) of dietary choline during the study period. Body composition and maximum strength were measured before and after training.

Results

Significant differences in strength (leg press 1RM + chest press 1RM) gains were observed between the groups (Low: 49.3±12kg vs. Adequate: 88.8±11kg, p<0.05/Low: 22.8±7% vs. Adequate: 46.8±7%, p<0.05) with ANCOVA analysis (covariate: gender) which was consistent with regression analysis (β=0.376, r2= 0.187, p<0.01). There was no difference in lean mass gain between the groups (Low: 1.49±0.3kg vs. Adequate: 1.92±0.3kg, p>0.05).

Conclusion

These results suggest that variability of dietary choline intake may affect strength gains in elderly people possibly through its effect on neurotransmitter (acetylcholine) availability.
Aging induced alterations in carotid baroreflex control of arterial blood pressure at rest and during dynamic exercise in humans
Authors: Fisher James P , Kim Areum , Young Colin N , Fadel Paul J
Published: June 2021

The arterial baroreflex is fundamental for evoking and maintaining appropriate cardiovascular adjustments to exercise. Given that exercise‐induced blood pressure (BP) responses appear exaggerated in older individuals, we sought to investigate how aging influences carotid baroreflex (CBR) regulation of BP during dynamic exercise. BP and heart rate (HR) were recorded at rest and during leg cycling performed at 50% HR reserve in 6 young (23±1 yr) and 6 older (60±1 yr) healthy men. Five second pulses of neck pressure and neck suction from +40 to −80 Torr were applied to determine the maximal gain (GMAX) of the full CBR function curve and examine baroreflex resetting during exercise. GMAX was similar in both groups at rest and during exercise. However, in older subjects the operating point (OP) of the modeled function curve was located further away from the centering point (CP) and towards the reflex threshold, both at rest (OP minus CP; −12±3 vs. −3±4 mmHg, older vs. young, P<0.05) and during exercise (OP minus CP; −10±2 vs. 0±3 mmHg, older vs. young, P<0.05), compared with the younger group. In addition, the magnitude of CBR resetting was ≈40% greater in older individuals. These findings suggest that both at rest and during dynamic exercise, the ability of the CBR to defend against a hypotensive challenge is reduced with increased age, while the magnitude of exercise CBR resetting is augmented.

Supported by NIH RO1HL093167
Aerobic interval training attenuates pathological cardiovascular remodeling in aortic‐banded miniature swine
Authors: Emter Craig A. , Baines Christopher P. , Bowles Douglas K.
Published: June 2021

Cardiac hypertrophy (CH) in response to hypertension or myocardial infarction is a pathological indicator associated with heart failure. Recent evidence indicates exercise training can attenuate or reverse this response creating a physiological phenotype. The purpose of this study was to examine cardiovascular remodeling in aortic‐banded (AB) sedentary (HFSED, n=6), AB exercise trained (HFTR, n=5; 3 days/wk, 15 wks, started 2 mo. post‐AB) and control sedentary (n=5) male Yucatan miniature swine. At the start of training, end diastolic and systolic volume and dimension were increased in both AB groups. Left ventricular (LV) hypertrophy, indicated by increased heart weight:body weight (BW), LV+septum (LV+S):BW, LV+S:RV, and cardiomyocyte cross‐sectional area, was similar in both AB groups postmortem. Increased LV fibrosis (23%) and collagen (36%) observed in HFSED animals was attenuated by exercise. LV mitochondrial dysfunction, measured by Ca2+ induced mitochondrial swelling, was greater in HFSED vs. HFTR animals. Exercise attenuated increased medial collagen deposition in the right coronary artery seen in HFSED, while increasing collagen density in the left circumflex artery. In conclusion, CH appears more physiological in exercise trained AB swine when compared to their sedentary counterparts as evident by decreased LV fibrosis, collagen, and mitochondrial dysfunction. NIH HL093982 & HL52490
Endurance Exercise Rescues Cardiomyopathy in Mitochondrial DNA Mutator Mouse Model of Aging
Authors: Safdar Adeel , Ogborn Daniel I , Bourgeois Jacqueline M , Melov Simon , Hubbard Alan , Hettinga Bart P , Kujoth Gregory C , Prolla Tomas A , Tarnopolsky Mark A
Published: June 2021

A causal role for mitochondrial DNA (mtDNA) mutagenesis in the etiology of age associated cardiomyopathy is supported by the polymerase gamma (PolG) mutator mouse, harbouring a proofreading‐deficient copy of PolG, which exhibits cardiac hypertrophy, mitochondrial dysfunction in cardiomyocytes, and reduced lifespan. Longitudinal studies demonstrate that endurance (END) training reduces risk of cardiovascular diseases and extends life expectancy. We aimed to delineate if END training can prevent cardiac abnormalities and attenuate mitochondrial dysfunction in heart of PolG mice. At 3‐mo, 36 PolG mice (♀ = ♂) were randomly assigned to sedentary (SED) or endurance training (15m/min for 45 min, 3x/week for 5 months) group. END suppressed cardiac hypertrophy (30%) and pathology (abnormal interventricular septal and free wall thickness), and increased mtDNA copy number (2‐fold), COX activity (38%) and lifespan of PolG mice (P<0.05). Using Roche NimbleGen mouse microarray platform, we observed that PolG‐SED hearts had ~100 DE genes (5% FDR) vs. wild‐type (WT) controls (P<0.05). END training normalized 22 DE genes in PolG heart to WT levels (P<0.05). We conclude that END training promotes cardiac mitochondrial oxidative capacity and partially normalizes the transcriptional signature to WT, contributing to the cardiac rejuvenation of PolG mice. We propose that END training is a valuable therapeutic intervention for attenuating cardiac pathology and related morbidity and mortality. (Funded by CIHR)
The pressor response mediated by group III muscle afferent mechanoreflex is altered in prehypertensive women
Authors: Park Seung‐Ae , Kim Kyung‐Ae , Choi Hyun‐Min , Park Siyoung , Lee Joon‐Hee , Chun Jong‐Mok , Nho Hosung , Kim Jong‐Kyung
Published: June 2021

Group III muscle afferent mechanoreflex evokes excessive blood pressure response in hypertensive rats. However, hemodynamic responses to the mechanoreflex are not well understood in prehypertensive women. Therefore, we investigated the effect of mechanoreceptors to physiological responses during passive ankle dorsiflexion in both normotension and prehypertension. Thirty healthy women (10 prehypertension and 10 normotension) were recruited for this study. Subjects were continuously instrumented to measure stroke volume (SV), heart rate (HR), cardiac output (CO), mean arterial pressure (MAP) throughout the experiment. To stimulate group III mechanoreceptors, passive ankle dorsiflexion was performed by a Cybex Norm for one minute. The results indicate that MAP was significantly increased during ankle dorsiflexion in both groups; however, this pressor response was significantly higher in prehypertensive women (9.8±1.7 vs. 13.7±1.5 mmHg). SV and CO were significantly increased in normotensive women, while no differences in prehyperentsive women. There was no difference in HR in both groups. Total vascular conductance was significantly decreased in prehypertensive women. It is concluded that excessive pressor response mediated by ankle dorsiflexion is occurred by overactivity of group III mechanorecptors and the mechanism is produced via peripheral vasoconstriction in prehypertensive women.
The sympathetic response to activation of the skeletal muscle mechanoreflex is enhanced in spontaneously hypertensive rats
Authors: Mizuno Masaki , Murphy Megan N. , Mitchell Jere H. , Smith Scott A.
Published: June 2021

Evidence suggests that the exaggerated cardiovascular response to exercise in hypertension is mediated, in part, by the skeletal muscle mechanoreflex (MMR). However, the mechanism by which the MMR produces this heightened response remains undetermined. Normally when stimulated, the MMR induces acute elevations in sympathetic nerve activity (SNA). Therefore, we hypothesized that the enhanced cardiovascular response to MMR activation in hypertension results from abnormally exaggerated increases in SNA. To test this hypothesis, mechanically sensitive afferent fibers (associated with the MMR) were selectively activated in normotensive Wistar‐Kyoto (WKY, n = 8) and spontaneously hypertensive (SHR, n = 6) decerebrate rats by passively stretching the triceps surae muscles of the right hindlimb (approximately 1000 g of tension developed). Passive stretch induced greater increases in renal SNA in SHR as compared to WKY (change from baseline = 139.4 ± 32.9 vs. 46.4 ± 9.5 %, respectively, P<0.05) as well as mean arterial pressure (change from baseline = 39.4 ± 12.3 vs. 13.6 ± 2.8 mmHg, respectively, P < 0.05). The results suggest that the exaggerated arterial pressure response to activation of the MMR in hypertension is mediated by abnormal augmentations in SNA. Supported by NIH HL‐088422
Cardiovascular responses to dynamic exercise in postmenopausal women
Authors: Kim Kyung‐Ae , Park Seung‐Ae , Choi Hyun‐Min , Park Siyoung , Lee Joon‐Hee , Chun Jong‐Mok , Nho Hosung , Kim Jong‐Kyung
Published: June 2021

Previous studies strongly indicate that the arterial baroreflex plays an important role in cardiovascular responses to dynamic exercise. However, the effect of arterial baroreflex on the hemodynamic responses to dynamic exercise is not well understood after menopause. Therefore, we investigated the cardiovascular responses during cycle exercise (30 W and 60 W) in healthy premenopausal and postmenopausal women. Thirty premenopausal and postmenopausal women were instrumented to measure heart rate (HR), cardiac output (CO) and mean arterial pressure (MAP). MAP was significantly increased with exercise intensity in postmenopausal women, while there was no difference in premenopausal women. CO, HR, total vascular conductance (TVC) and stroke volume increased with increasing workloads in both premenopausal and postmenopausal women. However, TVC was significantly lower after menopause at moderate workload compared to the premenopausal women (107.3±13.4 vs. 91.4±5.2 mm/min/Hg). The results indicate that higher MAP after menopause occurred due to combining increase in CO as well as substantial decrease in peripheral vascular conductance. We conclude that menopause altered normal cardiovascular responses to graded dynamic exercise. Additionally, after menopause significantly a higher increase in arterial blood pressure may be due to a depression in arterial baroreflex function during exercise.
Stimulation of the Efferent Vagus Nerve Mitigates Acute Lung Injury and Ventilator Induced Lung Injury
Authors: Dos Santos Claudia , Shan Yuexin , Akram Ali , Peng Claudia , Slutsky Arthur S , Haitsma Johannes
Published: June 2021

Rationale

Ventilator induced lung injury (VILI) significantly contributes to the mortality in patients with acute respiratory distress syndrome.

Objectives

To determine the role of vagus nerve signaling in VILI.

Methods

To determine whether vagus signaling plays a role in VILI we first demonstrated that disruption of the CAP reflex by bilateral vagotomy results in worsening lung injury in a mouse model of high‐volume‐induced lung injury. In a clinically relevant model of injurious mechanical ventilation following lung injury induced by hemorrhagic shock/resuscitation we then tested the hypothesis that electrical and pharmacological stimulation of the vagus nerve can attenuate lung injury in rats.

Results

Vagotomy exacerbates lung injury from high volume ventilation in mice as demonstrated by increased wet‐to‐dry ratio, infiltration of neutrophils in bronchoalveolar lavage fluid and lung tissues, and increased tissue levels of interleukin‐6. Vagotomy exacerbated while vagus stimulation attenuates lung injury in rats after ischemia reperfusion injury ventilated with either high or low volume strategies. Treatment of both mice and rats with the vagus mimetic drug, semapimod, resulted in decreased lung injury. Vagotomy also increased pulmonary apoptosis whilst vagus stimulation attenuated VILI‐induced apoptosis. In‐vitro studies suggest that vagus‐dependent effects on inflammation and apoptosis are mediated via the alpha 7 subunit of the acetylcholine nicotinic receptor effect on cyclic stretch‐dependent singling pathways c‐jun N‐terminal kinase (JNK) and Fas (TNF receptor superfamily, member 6).

Conclusion

Stimulation of the cholinergic anti‐inflammatory reflex may represent a promising alternative for the treatment of VILI.
Respiratory responses to NaHS are mediated by central mechanisms
Authors: Yu Jerry , Li Huafeng , He Yuwen , Walker Jerome
Published: June 2021

Hydrogen sulfide, H2S, is a gasotransmitter that serves a variety of important physiological functions. On the other hand, it also produces fatal toxicity. Respiratory arrest is major cause of death; however, the underlying mechanism remains unclear. In the current study, we recorded phrenic nerve activity to monitor the central respiratory output in anesthetized, open chest, mechanically ventilated rabbits and examined the respiratory response to intravenous as well as lung parenchymal injection of sodium hydrogen sulfide, NaHS. Intravenous injection of NaHS caused immediate hyperpnea and tachypnea, which was followed by apnea. These respiratory responses were sustained after bilataral vagotomy, indicating they are the result of extra‐vagal mechanisms such as direct central effect through the circulation. This statement was further strengthened by the fact that intraparenchymal NaHS injection produces hyperpnea and tachynea but not apnea when the ipsilateral pulmonary artery was occluded. Apnea ensued after releasing the occlusion. We conclude that the respiratory responses to H2S exposure are mainly centrally mediated. Apnea as well as tachypnea and hyperpnea are caused by direct action of the CNS, although the vagal afferents may also contribute to the early hyperpnea and tachypnea responses.

Supported by NIH (HL‐58727)
Distribution and Morphology of Catecholaminergic and Cholinergic Axons in Whole‐Mount Mouse Atria
Authors: Harden Scott W , Cheng Zixi (Jack)
Published: June 2021

We examined the effects of maternal diabetes on excitability, action potential (AP) properties and SK channels of PCMNs. Neonatal mice from OVE26 diabetic (Type 1; NMDM) and normal FVB (control) mothers which had been mated with normal fathers were used. XRITC was injected into the pericardial sac at P8 to label PCMNs. Two days later, XRITC‐labeled PCMNs in slices were identified. Whole‐cell current clamp was used to measure spike frequency, repolarization (half‐width), and afterhyperpolarization (AHP). Whole‐cell voltage clamp was used to measure outward and afterhyperpolarization currents (IAHP). Compared to control, we found (p<0.05) in NMDM that: 1) spike frequency decreased; 2) the half‐width and AHP peak amplitude increased; 3) the peak amplitude of outward transient currents and IAHP increased; 4) Ca2+‐sensitive transient outward currents and IAHP increased; 5) application of Ca2+‐free solution increased AP half‐width and decreased AHP amplitude; 6) apamin‐sensitive transient outward currents and IAHP increased; 7) blockade of SK channels with apamin increased AP half‐width and decreased AHP amplitude; 8) apamin application increased the firing rate to current injections and largely abolished the difference of the firing rate between control and NMDM. We suggest that the augmented SK currents may contribute to altered AP properties and the attenuated excitability of PCMNs in NMDM. NIH R01 HL79636.
Mechanisms Mediating Heart Rate (HR) Responses Evoked by Activation of NTS A1 Adenosine Receptors
Authors: McClure Joseph Martin , Minic Zeljka , Li Cailian , O'Leary Donal S. , Scislo Tadeusz J.
Published: June 2021

Our previous studies showed that activation of NTS A1 adenosine receptors inhibits transmission in baroreflex and cardiopulmonary chemoreflex pathways and resets HR and regional sympathetic baroreflex functions towards higher mean arterial pressure (MAP) which causes increases in mean arterial pressure and regional sympathetic nerve activity (Am J Physiol 294: H172–H182, 2008; FASEB J 23:610.12, 2009). However, baseline HR decreases in this setting suggesting that competitive mechanisms may be triggered (sympathetic activation and non‐baroreflex, likely vagal inhibition). Therefore in anesthetized (urethane/chloralose) rats we compared the parasympathetic and sympathetic contribution to the HR responses evoked by bilateral microinjections into the NTS of the selective A1 adenosine receptor agonist, N6cyclopentyladenosine (330 pmol/50 nl). Blockade of β1 adrenoceptors (atenolol, 2 mg/kg iv.) did not markedly affect the responses (Δ∫% −27.4±6.5 vs. −22.7±4.2 bpm, control vs. blockade, respectively). However, muscarinic blockade (atropine methyl bromide, 2 mg/kg iv.) virtually abolished the responses (Δ∫% −27.4±6.5 vs. 0.3±2.6 bpm, control vs. blockade, respectively). We conclude that whereas activation of NTS A1 adenosine receptors resets HR baroreflex function toward higher MAP, it also disinhibits the parasympathetic activity via a non‐baroreflex mechanism which thereby elicits bradycardia. NIH HL‐67814
Modulation of Baroreflex Sensitivity by Endogenous Angiotensins in Lamb Solitary Tract Nucleus
Authors: Shaltout Hossam A. , Rose James C. , Chappell Mark C. , Diz Debra I.
Published: June 2021

We and others find that within the nucleus of the solitary tract (NTS) of the rat endogenous Ang II attenuates while Ang‐(1–7) facilitates the baroreflex sensitivity (BRS) in the control of heart rate. It is not known whether this same relationship exists in the sheep NTS. Therefore, we performed microinjection studies in 6 wk old sheep (n = 5) under chloralose‐urethane anesthesia (35/750 mg/kg) which maintains both increases and decreases in BRS for heart rate control. To assess the effects of blockade of either the AT1 or Ang‐(1–7) (AT7) receptors, we tested BRS before and after bilateral NTS injection of the AT1 antagonist candesartan (CV, 200 pmol/200 nl at 4 injection sites) and retested the reflex again after the AT7 antagonist D‐Ala7‐Ang‐(1–7) (D‐Ala, 10 pmol/200 nl at 4 injection sites). BRS was tested using various doses of phenylephrine to determine the slope of the relationship between changes in mean arterial pressure (MAP) and pulse interval as ms/mm Hg. Resting BRS was 0.3 ± 0.2 ms/mm Hg and MAP was 81 ± 7 mm Hg. NTS injection of CV increased BRS to a new baseline of 1.0 ± 0.2 ms/mm Hg, (p<0.05). From this elevated level D‐Ala significantly reduced BRS back to baseline. There was no effect of either agent on MAP. These data suggest that baseline baroreceptor reflex control of heart rate in lambs is regulated by Ang II and Ang‐(1–7) in the NTS in an opposite manner. Support: HD‐047584, HD‐017644, HL‐51952.
Galanin reduces cardiac vagal acetylcholine release and bradycardia via a GalR1, protein kinase C dependent pathway
Authors: Herring Neil , Cranley James , Lokale Michael N , Habecker Beth , Paterson David J
Published: June 2021

Prolonged cardiac sympathetic nerve activation releases slowly diffusing co‐transmitters such as Galanin (Gal). We tested the hypothesis that Gal acts on local vagal neurons to reduce acetylcholine release and vagal bradycardia.

The GalR1 receptor was immunofluorescently co‐localized with choline acetyl‐transferase containing neurons in guinea pig right atria. The effect of Gal was established on the heart rate (HR) response to vagus nerve stimulation (VNS) in isolated guinea pig sinoatrial node/right vagus nerve preparations and also on 3H‐acetylcholine release from right atria during field stimulation. Gal (n=6) reduced the HR response to VNS at 1, 3 and 5Hz (significant at ≥100nM, p<0.05) but not to the stable analogue of acetylcholine, carbamylcholine (n=6). Gal (500nM, n=5) also significantly attenuated the release of 3H‐acetylcholine during field stimulation. The effect of Gal (100nM) on vagal bradycardia was abolished by the GalR1 antagonists galantide (100nM, n=5) and M40 (100nM, n=4) and also by the protein kinase (PK) C inhibitor calphostin C (100nM, n=5). The PKA inhibitor H89 (500nM, n=5) did not prevent the effect of Gal on vagal bradycardia. These results show that GalR1 is located on atrial cholinergic neurons and that Gal attenuates vagal bradycardia via a reduction in acetylcholine release mediated by a GalR1, PKC dependent pathway.

Supported by the British Heart Foundation
Does Infusion of Bacillus anthracis Toxins Produce Sympathoinhibition?
Authors: Kenney Michael J. , Fels Richard J.
Published: June 2021

Bacillus anthracis infection is a pathophysiological condition that produces shock‐like cardiovascular alterations. Bacillus anthracis produces two endotoxins, lethal toxin (LeTx; lethal factor + protective antigen) and edema toxin. Neurological complications are a critical component of the pathology produced by Bacillus anthracis toxins, however, little is known about the effect of these toxins on sympathetic nerve regulation. We tested the hypothesis that infusions of Bacillus anthracis toxins alter sympathetic nerve discharge (SND). Splenic, renal, and adrenal SND were recorded in urethane‐chloralose anesthetized rats. Rats with intact or denervated arterial baroreceptors (SAD) received intravenous lethal factor (100 μg/kg) + protective antigen (200 μg/kg) (LeTx) or vehicle, infused at 0.5 ml/hr. Mean arterial pressure (MAP), heart rate (HR), and SND were recorded continuously (up to 6 hrs) before and during intravenous toxin or vehicle infusions. Results indicate that LeTx produced marked reductions in MAP and HR that occurred several hours after initiation of infusion. The reduction in MAP was accompanied by inhibition of SND in both baroreceptor‐intact and SAD rats, indicating LeTx‐induced dysregulation of SND. These preliminary data provide evidence suggesting that Bacillus anthracis toxins can alter regulation of sympathetic nerve outflow. Funding provided by NIH HL092392.
Micro RNA 802 (Mir‐802) stimulates ROMK channels by suppressing caveolin‐1 expression during a high potassium (K) intake
Authors: Lin Daohong , Yue Peng , Pan Chunyang , Sun Peng , Wang Wenhui
Published: June 2021

The aim of the present study is to examine the role of Mir‐802 in mediating the effect of a high K intake on ROMK channel activity. Northern blot analysis demonstrated that a high K intake stimulated the Mir‐802 transcription in the mouse kidney. Expression of Mir‐802 decreased caveolin‐1 expression in both mouse collecting duct‐ and HEK cells. In contrast, suppression of endogenous Mir‐802 increased caveolin‐1 protein expression. Immunocytochemistry staining shows that caveolin‐1 and ROMK channels are co‐localized in the collecting duct. Moreover, gradient sucrose centrifuge revealed that ROMK proteins and caveolin‐1 were in the same layer. Also, caveolin‐1 is immunoprecipitated with ROMK and its N terminus was required for the interaction. Biotin labeling assay demonstrated that expression of caveolin‐1 decreased the ROMK1 expression in plasma membrane of HEK293 cells transfected with GFP‐ROMK1. In contrast, deletion of two putative caveolin‐1 binding sides (62FIFFVDIW69, 77WRYKMTVF84, 93FLFGLLWY100) increased the surface expression of ROMK1 channels. Finally, whole cell patch‐clamp experiments demonstrated that expression of Mir‐802 increased while overexpression of caveolin‐1 decreased K current in HEK293 cells transfected with GFP‐ROMK1. We concluded that Mir‐802 plays an important role in stimulating ROMK channel activity by suppressing caveolin‐1 expression in response to a high K intake.
Post‐Transcriptional Regulation of CD38 expression in human airway smooth muscle (HASM) cells
Authors: Jude Joseph Antony , Puvanendiran Shanmugam , Walseth Timothy , Solway Julian , Panettieri Reynold , Kannan Mathur S
Published: June 2021

CD38 is a membrane protein expressed in HASM cells and its induction by TNF‐α involves transcriptional and post‐transcriptional mechanisms. CD38‐null mice develop attenuated airway hyperresponsiveness compared to the wild‐type mice. TNF‐α causes greater elevation of CD38 expression in asthmatic HASM cells than in non‐asthmatic cells. The objectives of this study were to determine the role of 1) RNA binding protein HuR and 2) microRNAs in post‐transcriptional regulation of CD38 expression in HASM cells. Expression and sub‐cellular localization of HuR were determined by western blotting. CD38 mRNA stability was determined in HASM cells transiently transfected with HuR. Binding of HuR to an oligonucleotide representing the AU‐rich motif (ARE) of CD38 mRNA was determined by a pull‐down assay. Expression of the miRNA miR‐140‐3p was determined by qRT‐PCR. In HASM cells, HuR was localized to the nuclei and its expression was unaltered by TNF‐α, although TNF‐α exposure increased HuR binding to the oligo mimicking ARE of the CD38 3′UTR. CD38 mRNA decay and HuR levels were comparable in non‐asthmatic and asthmatic cells. HuR overexpression did not alter CD38 mRNA decay. MiR‐140‐3p expression was unaltered in non‐asthmatic cells by TNF‐α, whereas in asthmatic cells it was reduced. The differential induction of CD38 expression by TNF‐α in asthmatic ASM cells may arise from regulation by miR‐140‐3p, but not HuR, expression.