bluuebunny/crossref_metadata_2025 huggingface dataset:
Estrogen induces nitric oxide production in human bronchial epithelial cells
Authors: Townsend Elizabeth A , Thompson Michael A , Cassivi Stephen D , Pabelick Christina M , Prakash Y S
Published: June 2021

Women have a higher incidence and severity of asthma exacerbations compared to men. Asthma symptoms fluctuate with hormonal status suggesting a role for sex steroids in modulating bronchoconstriction. We have previously shown that acute estrogen decreases intracellular calcium in human airway smooth muscle thereby facilitating bronchodilation, similar to estrogen‐induced vasodilation. Akin to endothelium, airway epithelium is a source of nitric oxide (NO), a bronchodilator. We hypothesized that estrogens facilitate bronchodilation by generating NO in bronchial epithelium. In acutely dissociated human bronchial epithelial cells, 5–10 min exposure to 1 μM ACh or 17β‐estradiol (E2) (1 and 10 nM) resulted in increased DAF‐2 fluorescence (NO indicator). Both ER specific agonists THC (ERα) and DPN (ERβ) (10 nM,) induced NO production comparably. E2 effects were abrogated by the estrogen receptor (ER) antagonist ICI 182,780 (Faslodex®). eNOS phosphorylation was enhanced by E2 while E2‐induced NO production was attenuated by Ca2+ chelation (BAPTA; 20 μM, 30 min) and eNOS inhibition (L‐NAME). Overall, these data indicate a role for airway epithelium‐derived NO in the bronchodilatory effects of estrogens in human ASM.

Supported by NIH grants HL090595 (CMP), HL088029 & HL56470 (YSP), and Mayo Graduate School (EAT).
Loss of cilia alters airway epithelial cells and evokes an immune response
Authors: Gilley Sandra Kaye , Stenbit Antine E. , Sas Kelli M. , Flume Patrick A. , Bell P. Darwin
Published: June 2021

Deletion of the intraflagellar transport protein, polaris, results in loss of cilia. The purpose of this study was to characterize the effects of polaris deletion on ciliated airway epithelial cells and lung parenchyma. Utilizing a conditional floxed ift88 allele under the control of the estrogen receptor, 8 cre+ and 7 (control) cre− adult mice were induced with tamoxifen. Both cre+ and cre− mice, at either 3 wks or 3 months post tamoxifen, appeared to be healthy. Weights were not different and lungs looked grossly normal. At both time points western blot and immunofluorescence (IF) revealed a > 80% loss of polaris in cre+ lungs. Utilizing acetylated‐alpha tubulin as a marker of cilia, IF demonstrated a dramatic loss of cilia in airways from cre+ mice. Interestingly, in cre+ lungs, there was hypertrophy of airway epithelial cells, with increased cytoplasmic blebbing, and a decreased number of goblet cells. In BAL fluid and in lung parenchyma there was evidence of an increased inflammatory response in lungs from cre+ mice and a greater number of reactive type II pneumocytes. These changes were greater at 3 months versus 3 wks in lungs from cre+ mice. These results suggest that loss of cilia leads to morphologic changes of airway epithelial cells and initiates an enhanced inflammatory response in lung parenchyma. This mouse model may serve as a means for defining the role of cilia in the pathophysiology of lung injury. NIH/VA
Neonatal maternal separation promotes respiratory instability during heat exposure in 12 days old rats: sex‐specific role of O2 chemosensitivity
Authors: Kinkead Richard , Gulemetova Roumiana
Published: June 2021

Neonatal maternal separation (NMS) interferes with respiratory control development. In adult male (but not female) rats, NMS increases the hypoxic ventilatory response (HVR) and augments respiratory instability during sleep. Because the effects of NMS on breathing prior to puberty are unknown, we tested whether NMS augments respiratory instability and the HVR in 12 days old rats. Pups subjected to NMS were placed in an incubator 3h/day from P3 to P12. Controls were undisturbed. Breathing and apnea index were measured in normoxia with plethysmography. Recording chamber was maintained either at 24°C or 29°C. Peripheral chemosensitivity was assessed by hypoxia (9% O2; 5 min). Heat augmented both the HVR and apnea index. Although NMS had no effect on the HVR at either temperature it increased the apneas index in males only. Males: unlike controls, NMS pups showed no correlation between the HVR and apnea index, suggesting that mechanisms other than chemosensitivity contribute to respiratory instability in this group. Females: NMS pups (not controls) showed a significant correlation between HVR and apnea index. Thus unlike males, peripheral chemoreceptors contribute to respiratory instability in NMS females. At P12, the effects of NMS on breathing differ from those reported in adults; however, sex hormones already appear to play an important role in the manifestation of stress‐related respiratory control disorders.
Postnatal development of ATP signaling involved in respiratory response to hypoxia in rats.
Authors: Niane Lalah , Donnelly David F. , Joseph Vincent , Bairam Aida
Published: June 2021

In adults, ATP, acting through P2X receptors, plays an important role in both carotid body excitation and brainstem respiratory stimulation during hypoxia. In this study, we addressed whether the contributions of P2X receptors undergo developmental changes in newborn, during which the hypoxic ventilatory response (HVR) matures. Using whole body plethysmography, HVR was measured in rats at 1, 4, 7, 12 and 21 postnatal days before and after intraperitoneal injection of suramin (P2X receptor antagonist, 40mg/kg) or vehicle. At each age, suramin reduced breathing frequency but not tidal volume (p<0.05, suramin vs vehicule group). The reduction in frequency was age dependent with greater effect at older ages (p<0.05). Using single‐unit recordings of carotid body activity, in vitro, suramin depressed discharge activity in both normoxia (150 torr PO2) and hypoxia (60 torr PO2), but the magnitude of depression was not age dependent. We conclude that ATP acting through P2X receptors plays an important role, both peripherally and centrally, in the HVR and this undergoes a developmental increase in the newborn period. These developmental changes primarily occur centrally. Founded PF‐RSR du FRSQ, IRSC.
New lentiviral vector to selectively target glycinergic neurons in the brainstem
Authors: Abdala Ana Paula Lima , Liu Beihui H. , Rybak Ilya A. , Smith Jeffrey C. , Paton Julian F. R.
Published: June 2021

Inhibitory interactions between populations of inspiratory and expiratory neurons within the brainstem respiratory network are paramount for the operation of the respiratory CPG. However, the exact role that populations of inhibitory glycinergic neurones play in rhythm and pattern generation is unknown. The lack of information results from technical difficulties in identifying and targeting these neurones in vivo. To overcome this problem, we explored the sequences 5′ upstream of the glycine transporter‐2 gene (GlyT2), a reliable marker for glycinergic neurons, and generated lentiviral vectors (LV) to express far‐red fluorescent protein (Katushka1.3), which were then, tested in vivo using microinjections into the rat brainstem. All fragments longer than 1.5 kb conferred specific expression in glycinergic neurons with the 1.5 kb one providing the strongest transcriptional activity. We then injected the 1.5 kb LV into different sites of the brainstem of transgenic mice expressing enhanced green fluorescent protein (eGFP) in glycinergic neurons to confirm the specificity of this vector and then compared sites with abundant glycinergic innervation, e.g. gigantocellular reticular nucleus, with sites where this innervation was absent, e.g. inferior olive. We concluded that this novel vector allows selective targeting of glycinergic neurons within the brainstem respiratory network. Support: NIH R01 NS057815, BHF RJ/07/006.
Disturbed inspiratory rhythm in rat brainstem slices by seizure‐like bursting due to theophylline‐evoked GABAA receptor block
Authors: Panaitescu Bogdan , Kuribayashi Junya , Ruangkittisakul Araya , Ballanyi Klaus
Published: June 2021

Methylxantines theophylline and caffeine can evoke seizures at clinical doses. Here we studied if this can disturb inspiratory activity and whether blockade of γ‐aminobutyric acid‐A (GABAA) receptors is involved.

In newborn rat brainstem‐spinal cords, inspiratory‐related cervical nerve bursting driven by the pre‐Bötzinger Complex (preBötC) was perturbed by >0.1mM caffeine or theophylline. At millimolar levels, seizure‐like discharges occurred that resembled non‐respiratory activity due to bicuculline. In brainstem slices, seizure‐like bursting in inspiratory active hypoglossal nucleus or preBötC area was less pronounced than in the en bloc model for the same concentration. GABAA receptor activation with muscimol hyperpolarized preBötC neurons with a decrease of input resistance and blocked inspiratory rhythm. Rhythm restoration by 5–10mM theophylline in muscimol was accompanied by recovery of membrane potential and resistance.

Findings suggest that methylxanthines at millimolar doses perturb preBötC bursting in the slice model via blockade of GABAA receptors, whereas disturbance of rhythm at submillimolar levels in the en bloc model may be due to another mechanism.

Supported by AHFMR, CIHR, MFN‐Health
Exercise‐induced flow limitation in adults with a history of bronchopulmonary dysplasia.
Authors: Lovering Andrew T , Yang Ximeng , Laurie Steven S , Elliott Jonathan E , Beasley Kara M , Hawn Jerold A , Gladstone Igor M
Published: June 2021

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of infancy characterized by poor pulmonary function at term that persists into adolescence. Because exercise causes a significant increase in ventilation, we hypothesized that adults with a history of BPD would be susceptible to flow limitation during exercise at relatively low metabolic rates. Resting pulmonary function and maximal oxygen consumption (VO2max) on a cycle ergometer were determined in six subjects (1 female) born preterm (≤32 weeks) with a documented history of BPD. On a separate day, exercise flow‐volume loops were recorded during each 4 min exercise stage at 25, 50, 75 and 90% of VO2max. Resting forced‐expiratory flow at 50% of vital capacity was 2.9(1.6) L/s, mean(SD), [57(32)], [%predicted(SD)] and VO2max was 40.2(18.2) mL/kg/min [110.8(36)]. Flow limitation (%tidal volume) occurred at rest in one subject (96); 25% of VO2Max, in 2 subjects (22.7–83.7); 50% of VO2Max, in 3 subjects (47–87); and in all subjects at 75 and 90% VO2Max,(17–87) and (58.4–92.5), respectively. Exercise‐induced flow limitation was observed in all BPD subjects at low to moderate metabolic rates. Our data suggest that because individuals with BPD are flow limited during exercise, they would likely have an increased work of breathing for a given ventilation compared to their full term counterparts who do not have flow limitation. Support: AHA SDG 2280238
Oxygen Uptake Efficiency During Cardiopulmonary Exercise Testing in Healthy Subjects
Authors: Sun Xingguo , Hansen James E
Published: June 2021

When evaluating circulatory efficiency in transporting O2 from the lung to the metabolizing tissues in normal subjects or in patients with cardiovascular disease, the relationship of oxygen uptake (VO2, mL/min, STPD) to ventilation (VE, L/min, BTPS), i.e. oxygen uptake efficiency (OUE) has been useful for heart failure prognosis. Although it has not been normalized to the variables of age, body size, gender and fitness, OUE is often reduced in patients with cardiovascular diseases and ventilation/perfusion mismatching. To better quantify and report OUE in normal subjects and patients, we considered several VO2 and VE relationships during exercise and how the above variables influenced their values.

Methods and Results

We studied 474 healthy adults, aged 17–78 years during increasing cycle and/or treadmill cardiopulmonary exercise at three sites, reducing the total VE by the equipment dead space ventilation. Three methods of calculation were analyzed: 1) OUE plateau (OUEP). The OUEP and OUE@AT were similar, highly reproducible, and less variable than the OUES (p<0.0001), and were unaffected by the study sites or methods of exercise. The resultant prediction equations for men are: OUEP(mL/L)=35.4–0.185xyears+0.080xcm (−2.2 for women).

Conclusions

The OUEP and OUE@AT are the preferred methods to measure circulatory efficiency.
ES‐1 BREP: Chinese herb and vibration combined with resistance exercise countermeasures main leg venous vascular characteristics during 60d head‐down bed rest
Authors: Ming Yuan , Custaud Marc‐antoine , Yinghui Li , Arbeille Philippe , Yanqiang Bai , Coupe Mickael , Shizhong Jiang
Published: June 2021

Spaceflight and head‐down bed rest (HDBR) induce cardiovascular deconditioning, which includes modified leg venous hemodynamics. In this study, the leg venous vascular characteristics were measured in 7 controls and 7 subjects with Chinese herb and vibration combined with resistance exercise respectively by strain gauge venous occlusion plethysmography before, at day 38 and 52 of HDBR. After 38d bed rest, leg vein compliance significantly decreased combined with increased venous resistance in three groups. However, compared with control and exercise groups, these changes were smaller in Chinese herb group. After 52d HDBR, the leg vein compliance and vein resistance in Chinese herb and control group had an ongoing decrease and increase, respectively. However, in exercise group, such changes maintained at the level of 38d HDBR. These results suggested that Chinese herb and exercise countermeasure had a better effects on the modified leg venous vascular characteristics induced by 38d and 52d HDBR, respectively. (Funded by manned‐space project of China)
Endurance training attenuates loss of bone strength in the polymerase gamma mutator mouse model of aging
Authors: Antolic AnaMaria , Safdar Adeel , Bourgeois Jacqueline M , Hettinga Bart P , Wohl Gregory R , Kujoth Gregory C , Prolla Tomas A , Tarnopolsky Mark A
Published: June 2021

A causal role for mtDNA mutagenesis in aging‐associated bone loss is supported by recent studies demonstrating that the polymerase gamma (PolG) mutator mouse, harbouring a proofreading‐deficient copy of PolG, exhibits a significant reduction in whole‐body bone mineral content and density. Physiological aging is accompanied by kyphosis, osteoporosis and an increased incidence of fractures. Anecdotal evidence from human and rodent studies suggests that endurance training prevents loss of bone mineral density, mobility and posture, and is recommended to reduce the likelihood of falling and associated morbidity and mortality. We investigated whether endurance training can prevent bone strength decrements in PolG mice. At 3 months of age, 24 PolG mice (♀ = ♂) were randomly assigned to a sedentary (SED) or forced‐endurance training (END; 15m/min for 45 min, 3x/week for 5 months) group. PolG‐SED mice exhibited a marked decrease in maximal load (33%), maximal energy (39%) and stress (33%) vs. wild‐type (WT) controls (P<0.01) with a trend toward decreased stiffness (19%) in the femur (P<0.07) and bone area (9%) at the mid‐diaphysis (P<0.08). PolG‐END showed an improvement in all structural parameters (P<0.01) returning to WT levels. We found no differences in femur length, periosteal and endosteal area at the mid‐diaphysis. Five months of endurance training rescued the loss of femur strength in PolG mice. (Funded by CIHR)
Effect of the Pilates Exercise on the Health Physical Fitness, Immunoglobulin and Sex Hormone in Female College Students
Authors: Na Chan Il , Kim Donghee , Lee Hayan , Jung Heymin , Jung Jaekwan , Kim Hyeok , Yang Meehyun , Kwon Soyoung , Jung Woosuk , Moon Hyunwoong , Baek Changyei , Kim Daeyeol
Published: June 2021

The purpose of this study was to examine the effects of a 10week Pilates exercise program on the health physical fitness, immunoglobulin and sex hormone in female college students. Subjects were divided into pilates group and control group. Exercise program was in the form of Pilates exercise, warm‐up, main exercise, cool‐down, 4 times a week, during 10week with an exercise intensity of 50–60%HRmax(1–5 weeks) and 61–70%HRmax(6–10 weeks). Before and after Pilates exercise program, the health physical fitness, immunoglobulin and sex hormone were analyzed. Health physical fitness were significant increase in the muscular strength, muscular endurance, flexibility and cardiorespiratory endurance of Pilates exercise group as the duration of exercise go by. Immunoglobulin, there were significant increase in the IgG, IgM, IgD, IgE of Pilates exercise group as the duration of exercise go by. Sex hormone were significant increase in the E2 and progesterone of Pilates exercise group as the duration of exercise go by. Pilates exercise was an effective exercise which provided an positive improvement of the health physical fitness and immunoglobulin after 10week exercise, especially sex hormone was showed positive change after 5week exercise. It is conclude that Pilates exercise is a good one for the promotion of physical metabolism and physiological function by positive change of immunoglobulin and sex hormone.
Effect of Walking Exercise Types on Body Composition and Eating inhibition and facilitation Hormone
Authors: Na Chan Il , Kim Donghee , Lee Hayan , Kim Hoewon , Jung Jaekwan , Kim Hyeok , Yang Meehyun , Kwon Soyoung , Jung Woosuk , Moon Hyunwoong , Baek Changyei , Kim Daeyeol
Published: June 2021

The purpose of this study was to evaluate the effects of walking exercise types(walking, power walking, nordic walking) on body composition and hormones of abdominal obese women. Subjects were divided into 4groups and performed exercise with 4 types walking for 12 weeks, 1hour/day, 4days/week. 50~60% of VO2max. In stride and speed of power walking and nordic walking with stick grip subjects walked with height‐80cm/step and 5–6km/h powerfully stick grip. Body composition(waist, %fat, WHR, BMI), eating inhibition and facilitation hormones(serotonin, norepinephrine, TNF‐¥á) were analysed. Body composition was changed positively good for health by three types walking. Especially the effects of nordic walking group was highest of all groups. Serotonin of all exercise group decreased at 12 weeks after beginning exercise(p<.01). All exercise groups lower at 12 weeks after beginning exercise than control group(p<.01). Norepinephrine and TNF‐¥á of all groups were not different between times and groups(p<.01). Power walking and nordic walking could positively affect body composition and eating inhibition and facilitation hormones. All exercise group could positively affect eating inhibition and facilitation hormone. Because of the increased level of serotonin caused by exercise effect, trainees did not feel hunger in comparison to non‐trainees.
Effect of Hand‐weight Walking on Body Composition, Lipoprotein Metabolism and Obesity Hormone of the Obese Middle‐school Girls
Authors: Na Chan Il , Kim Donghee , Lee Hayan , Shim Eunhwa , Jung Jaekwan , Kim Hyeok , Yang Meehyun , Kwon Soyoung , Jung Woosuk , Moon Hyunwoong , Baek Changyei , Kim Daeyeol
Published: June 2021

This study was designed to investigate effect of the walking exercise and hand‐weight walking exercise on body composition, lipid protein, and obesity‐hormone in the obese middle‐school girls 4groups. Subjects were divided into walking exercise group(WEG, n=7); hand‐weight walking exercise group(HEG, n=7), control group(CG, n=7) to WEG and HEG exercised with 50 minutes a day, five times a week for 10 weeks. Especially the load of the HEG was one kilogram dumbbell on both hand. There was significant decrease in the weight of HEG and %Fat or WEG & HEG as the duration of exercise go by. And there was significant difference between the groups at 10‐week. There was significant decrease in the TC and TG of WEG and HEG and in the LDL‐C of HEG as the duration of exercise go by. And there was significant difference between the groups at 5 and 10 week. There was significant increase in the HDL‐C of WEG and HEG as the duration of exercise go by. And there was significant difference between the groups at 5 and 10 week. There was significant decrease in the leptin of WEG and HEG as the duration of exercise go by. And there was significant difference between the groups at 5 and 10 week. And the ghrelin was vise versa. Thus, this study shows that the walking exercise and hand‐weight walking exercise will help to achieve positive effects on body composition, lipoprotein metabolism and obesity hormone in the obese middle‐school girls.
The effects of creatine and exercise on skeletal muscle of FRG1‐transgenic mice
Authors: Ogborn Daniel I , Safdar Adeel , Hettinga Bart P , Crane Justin D , Tupler Rossella , Tarnopolsky Mark A
Published: June 2021

Transgenic overexpression of Fascioscapulohumeral Muscular Dystrophy (FSHD) Region Gene 1 (FRG1) results in severe muscle atrophy and weakness reminiscent of the human disease FSHD. Treatments that act to mitigate muscle dysfunction in the FRG1‐transgenic mouse could hold therapeutic benefit to FSHD patients. Forty FRG1 mice were divided into sedentary, creatine (Cr), and combination creatine and exercise treated groups (CrEx). Creatine was incorporated into standard rat chow at 2% (w/w) and animals exercised in thirty minute bouts at 12–15m/min, three times per week over 52 days. There were no effects of any treatment on bodyweight however quadriceps weight increased 15% in CrEX but not in Cr (P<0.05). CrEX had greater percentage improvements in grip strength (147%, P<0.05) and Rotarod fall speed (204%, P<0.001). As Cr resulted in no functional improvements, the positive effects of CrEX appear to be mediated by exercise, however the potential synergistic action of the combined treatment cannot be excluded. Low intensity exercise attenuates the atrophy and muscle dysfunction associated with FRG1 overexpression, resulting in modest improvements in muscle function. The mechanisms responsible for the beneficial effects of exercise remain to be determined.
COMPARISON BAROREFLEX BETWEEN MALE AND FEMALE RATS: ROLE OF EXERCISE TRAINING
Authors: Machert Henrique , Sartori Michelle , Sanches Iris Callado , Jorge Luciana , Dias Danielle da Silva , Mostarda Cristiano , Irigoyen Maria‐Cláudia , De Angelis Kátia
Published: June 2021

The objective of this study was to compare arterial baroreflex control between males and females rats, as well as submitted to an aerobic exercise training (ET). Wistar rats (n=32) were divided into 4 groups: sedentary (SM) and trained (TM) males, and sedentary (SF) and trained (TF) females. Arterial pressure (AP) and heart rate (HR) signals were directly recorded. The baroreflex sensitivity (BRS) was evaluated by tachycardic (TR) and bradycardic (BR) responses induced by AP changes, and also by the spontaneous BRS (alpha index) obtained by spectral analysis. The AP was similar between studied groups. Trained groups presented resting bradycardia. The BR was similar between SM and SF groups; and it was higher in TM (vs.SM) and to SF (vs.TF). The TF presented reduced BR (vs.SM and SF). The TR was higher in SF, TF and TM groups (vs.SM). The alpha index was increased in SF rats when compared to SM rats (1.03±0.12 vs. 0.69±0.09 ms/mmHg). The ET induced a reduction in TF group (0.60±0.08 ms/mmHg vs. SF), reaching similar values compared to SM group. The TM group (1.07±0.13 ms/mmHg) presented higher alpha index (vs.SM). These results showed enhanced BRS in females than in male rats. The ET induced resting bradycardia in both gender, but the improvement in BRS was just observed in trained males. These findings indicate important differences in cardiovascular reflex control associated with gender.
Regulation of Annexin A1 in the macula densa: association with neuronal nitric oxide synthase and cyclooxygenase‐2
Authors: Paliege Alexander , Seidel Saskia , Roschel Tom , Mutig Kerim , Bachmann Sebastian
Published: June 2021

Aim of the present study was to determine the effects of salt transport on the expression of Annexin A1 (ANXA1) in the macula densa (MD) and its association with cyclooxygenase‐2 (COX‐2) and neuronal nitric oxide synthase (NOS1). The MD associated expression of ANXA1, NOS1 and COX‐2 were determined by immunohistochemistry and cell counting on kidney sections of furosemide treated rats. Association of ANXA1 with NOS1 and COX‐2 was studied by double labelling immunofluorescence. Furosemide treatment caused a strong increase in the number of ANXA1 expressing macula densa cells (51±16 vs. 126±19 cells/100 glomeruli; p<.05). The number of NOS1 and COX‐2 expressing cells were similarly increased (NOS1: 84±14 vs. 186±14 cells/100 glomeruli; p<.05 and COX‐2: 54±9 vs. 183±24 cells/100 glomeruli; p<.05). Double labelling immunofluorescence showed a frequent (90–100%) co‐expression of ANXA1 with NOS1 and COX‐2 in control‐ and furosemide treated animals. In summary we have shown that ANXA1 expression in the MD of rats is stimulated by furosemide treatment and colocalizes with the MD enzymes NOS1 and COX‐2. ANXA1 may therefore be critically involved in the regulation of MD signalling.
Interaction of tricyclic antidepressants with the ha3β4 nicotinic receptor
Authors: Ahmad Ali H , Feuerbach Dominick , Jozwiak Krzysztof , Arias Hugo R
Published: June 2021

The interaction of tricyclic antidepressants (TCAs) with human (h)a3β4 nicotinic acetylcholine receptor (AChR) was compared to that for mecamylamine. The results established that: (a) [3H]imipramine binds to a single site with high affinity (Kd = 0.41 ± 0.04 μM), (b) imipramine inhibits [3H]imipramine binding to resting AChR with the same affinity as to desensitized AChR, suggesting that TCAs do not distinguish between these conformational states, (c) imipramine inhibits [3H]ibogaine binding, suggesting mutual interaction between both compounds, (d) both TCAs and mecamylamine inhibit (±)‐epibatidine‐induced Ca2+ influx with potencies in the same concentration range, but only TCAs inhibit [3H]imipramine binding to ha3β4 AChRs. This is supported by our molecular docking results, where imipramine, in the neutral and protonated states, interacts with the leucine (position 9′) and valine/phenylalanine (position 13′) rings, while protonated mecamylamine interacts with the outer ring (position 20′). Our data suggest that TCAs and ibogaine bind to overlapping sites located between the serine and valine/phenylalanine rings in the ha3β4 AChR ion channel, while protonated mecamylamine can be attracted to the channel mouth before blocking ion flux by interacting with a luminal site in its neutral state. Support: Science Foundation Arizona.
PI3K and MAPK Activation During Eccentric Cardiac Hypertrophy
Authors: Zhao Aiqiu , Alvin Zikiar , Cousins Valerie , Haddad Georges E.
Published: June 2021

Development of cardiac hypertrophy is partly mediated by humoral factors such as IGF‐1. The role of related kinases in the development of cardiac hypertrophy is still unclear. This study elucidates the role of MAPK and PI‐3K in the transduction of IGF‐I signaling during the development of eccentric cardiac hypertrophy. Adult Sprague‐Dawley rats were shunted (aorto‐caval) to induce eccentric cardiac hypertrophy which developed over 2 weeks. Hearts were retrogradely superfused with Tyrode (control), or IGF‐I (10−8M) or respective kinase inhibitor (10−6M) in the presence or absence of IGF‐I (10−8M). MRI showed an increase in LV‐EDV (62%) and its wall thickness (40%) in the shunt rat, concurrent with greater relative heart weight. Hypertrophied hearts had higher activity levels for ERK1/ERK2 (54%/157%), p38 (57%) and Akt (64%) as measured by western blot. In normal hearts, IGF‐I increased the activity of ERK1/ERK2 (38%/105%), p38 (109%) and Akt (95%); whereas in the hypertrophied hearts it increased only that of Akt (2.4 fold). Treatment with either ERK1/2 inhibitor (PD98059; 10−6M), p38 inhibitor (SB203580, 10−6M) or PI‐3K inhibitor (LY294002, 10−6M) reduced the activation level of the respective kinase in the hypertrophied hearts only. LY294002 reduced the activation of Akt by IGF‐I in both sham (62%) and shunt (75%). Thus we conclude that IGF‐I effects are mediated by PI‐3K and not MAPK in the hypertrophied hearts.
MIP/MTMR14 is implicated in skeletal muscle aging
Authors: Brotto Leticia , Craig Robin , Hall Todd , Loghry Michael , Valdivia Hector , Nosek Thomas , Shen J , Qu C‐K , Brotto Marco
Published: June 2021

We recently discovered a muscle‐specific inositol phosphatase (MIP/MTMR14) and demonstrated that systemic ablation of MIP induces intracellular elevation of PI(3,5)P2 in skeletal muscle cells, decreases store‐operated calcium entry, increases resting calcium, and enhances susceptibility to in vitro fatiguing stimulation after exercise (Nat Cell Biol, 2009). We also showed that PI(3,5)P2 directly binds to, activates the RyR1, and increases the open probability of the sarcoplasmic reticulum calcium channel. Here, we show that MIP expression and enzymatic activity is drastically reduced in aged compared with wild type muscles. Muscles from MIP KO animals display a combination of aging‐related muscle function changes such as reduced muscle strength, power, and activity that gradually and prematurely manifest between 12–18 months of age. We are now investigating the molecular mechanisms of MIP/PI(3,5)P2 modulation of muscle function during aging. We propose that a reduction in MIP with age is one of the factors which contribute to sarcopenia making the MIP KO a useful animal model for better understanding natural sarcopenia.

Support: NIH‐TREC grant to TN, CQ, MB. American Heart Association Grant to MB.
Thyroid hormone increases rapidly the length of the AT1R mRNA poly‐A tail in cardiomyocytes
Authors: Diniz Gabriela Placoná , Bruneto Erika , da Silva Francemilson Goulart , Nunes Maria Tereza , de Chaves Maria Luiza Morais Barreto
Published: June 2021

Objective

Angiotensin II type 1 receptor (AT1R) participates of thyroid hormone (TH)‐induced cardiomyocyte hypertrophy. In addition, TH modulates rapidly the AT1R expression. However, the possible mechanism involved in this response is unknown. The aim of the present study was to investigate the T3 influence in the length of the AT1R mRNA poly‐A tail in cardiomyocytes.

Methods

Cardiomyocytes cultures were prepared from ventricles of neonatal Wistar rats by colagenase/pancreatin method. The cells were treated with serum‐free medium (control cells) or serum‐free medium containing T3 (10nM) for 5, 10, 15 and 30 minutes. The polyadenylation of the AT1R mRNA was evaluated by Rapid Amplification of cDNAs ends ‐ poly(A) test. The results are expressed in percentage as mean±SD. Data were analyzed using one‐way analysis of variance, followed by Tukey's post hoc test. Values of P<0.05 were considered statistically significant (n=5).

Results

The cardiomyocytes treated with T3 for 5 (157, P<0.01), 10 (172, P<0.01), 15 (167, P<0.01) and 30 minutes (140, P<0.01) showed a significant increase in the length of the AT1R mRNA poly‐A tail compared with that observed in the control cells (100%).

Conclusion

These results demonstrate for the first time that T3 stimulates rapidly the polyadenylation of the AT1R mRNA, which may be contributing to the rapid increase on AT1R expression promoted by TH.
AMPK signaling pathway is downregulated by Thyroid Hormone in cardiomyocytes
Authors: Takano Ana Paula Cremasco , Diniz Gabriela Placoná , de Chaves Maria Luiza Morais Barreto
Published: June 2021

Objective

Thyroid hormone (TH) modulates rapidly several signaling pathways which have been implicated in cardiac hypertrophy. In addition, the AMP‐activated protein kinase (AMPK) also plays an important role in regulating cardiac hypertrophy. The aim of the present study was to investigate the TH effect on AMPK signaling pathway in cardiomyocytes.

Methods

Cardiomyocytes cultures were prepared from ventricles of neonatal Wistar rats by colagenase/pancreatin method. The cells were treated with serum‐free medium (control cells) or serum‐free medium containing T3 (10nM) for 5, 10, 15 and 30 minutes. The AMPK, LKB1 and protein phosphatase 2C (PP2C) were analyzed by Western Blot. Data were presented as mean±SD and were evaluated using one‐way analysis of variance. Values of P<0.05 were considered statistically significant.

Results

The cardiomyocytes treated with T3 for 10 and 15 minutes presented a significant decrease on AMPK (86.21±4.62 and 74.32±9.23, P<0.05) and LKB1 (65.18±5.17 and 67.43±4.92, P<0.01) phosphorylation levels, as well as on PP2C levels (77.5±5.55 and 75.21±9.83, P<0.05) in relation to control cells.

Conclusion

These data demonstrate for the first time that TH modulates rapidly the AMPK signaling pathway in cardiomyocytes cultures. The possible involvement of this signaling pathway in the modulation of TH‐induced cardiomyocyte hypertrophy remains to be investigated.
Heart rate control, but not the ventilatory response to CO2, is altered in 5HT1A receptor knock‐out (KO) mice during early development: possible relevance for Sudden Infant Death Syndrome (SIDS)
Authors: Barrett Karlene , Daubenspeck Andrew , Li Aihua , Nattie Eugene
Published: June 2021

Abnormalities in the medullary serotonin (5HT) system, including a decrease in the 5HT1A receptor binding density, have been implicated in the sudden infant death syndrome (SIDS), but it is uncertain how such abnormalities translate into a mechanism for its pathogenesis. Using the 5HT1A receptor KO mouse as a model of a system with reduced 5HT1A activity, we studied breathing, heart rate and the occurrence of spontaneous bradycardias in KO and control mice of both genders in air and in response to 5% CO2 at postnatal days (P) 5, 15 and 25. Breathing, represented as VE/VO2, was unaffected by the absence of the 5HT1A receptor both in air and in response to 5% CO2 at all ages studied, and in both genders, except in the P15 heterozygous males, that had a 42% reduction in the VE/VO2 in air. Heart rate was significantly reduced at P5 in females in air and CO2, and in P15 males in air. P15 and P25 KO male pups had 6 and 7.5 – fold more spontaneous bradycardias, respectively in air, and time and frequency domain analyses of the R‐R intervals at these two ages showed greater variability in the KO pups compared to controls during CO2. These data suggest that heart rate control during early development is adversely affected in mice lacking the 5HT1A receptor. (HD036379; 5HT1A KO mice were generously supplied by R. Hen)
Temperature dependence of signal processing in nucleus tractus solitarius (NTS) 2nd‐order neurons in Syrian hamsters
Authors: Sekizawa Shin‐ichi , Horowitz John , Horwitz Barbara A , Chen Chao‐Yin
Published: June 2021

Previous studies involving EEG measurements indicate that during hibernation, cortical and hippocampal activity is highly attenuated, but brainstem cardiorespiratory reflexes appear to remain actively involved in maintaining homeostasis. We tested the hypothesis that at low temperatures, neurons in the NTS change their properties yet retain their ability to support signal processing over central reflex pathways. Using patch clamp techniques, we measured the temperature dependence of signal processing in 2nd‐order neurons in NTS slices from euthermic Syrian hamsters (Mesocricetus auratus). The amplitude and onset latency of EPSCs evoked by sensory afferent stimulation were similar at 33°C and 24°C. At 15°C, there was a 77% decrease in amplitude and 4‐fold increased in onset latency. Spiking responses to depolarizing current injections linearly decreased as temperature dropped from 33°C to 15°C (p<0.001). This decreased spiking response was associated with changes in action potential waveform: a significant increase in peak amplitude (19mV) and a 5‐fold increase in width. Data are consistent with our hypothesis and suggest that decreased synaptic transmission and spiking response may be offset by an enhanced amplitude and duration of action potentials to preserve signal processing. (Support: R01 HL091763)
Activation of NTS A2a Adenosine Receptors Impairs Cardiopulmonary Chemoreflex Control of Renal (RSNA), Adrenal (ASNA) and Lumbar (LSNA) Sympathetic Nerve Activity
Authors: Minic Zeljka , O'Leary Donal S. , Scislo Tadeusz J.
Published: June 2021

Activation of NTS A2a adenosine receptors increases ASNA, decreases RSNA and does not alter LSNA (Clin Exp Physiol Pharmacol 28: 120–124, 2001). A similar pattern of regional sympathetic responses was occasionally observed following activation of cardiopulmonary chemoreceptors. As A2a adenosine receptors may facilitate neurotransmitter release it was likely that these receptors may facilitate the cardiopulmonary chemoreflex. In the present study we compared the regional sympathetic responses evoked by right atrial injections of 5HT3 receptor agonist, phenylbiguanide (PBG, 1–8 μg/kg), before and after stimulation of NTS A2a adenosine receptors (microinjections of CGS21680, 20 pmol/50 nl) in urethane/chloralose anesthetized rats (n=7). Activation of cardiopulmonary chemoreceptors evoked differential, dose dependent sympathoinhibition RSNA>ASNA>LSNA). Surprisingly, the responses in all sympathetic outputs (Δ%) were similarly attenuated following stimulation of NTS A2a adenosine receptors (−95.5±1.8 vs. −60.3±5.3, −74.9±7.1 vs. −44.6±8.6, −56.4±3.6 vs. −34.61±5.6, for RSNA, ASNA and LSNA, respectively, at the maximal dose of PBG). We conclude that A2a adenosine receptors may facilitate NTS neurons/terminals which inhibit cardiopulmonary chemoreflex pathway. NIH HL‐67814
Structural integration and cardiovascular effects following transplantation of endothelial progenitor cells (EPCs) into the brainstem of rats
Authors: Baquero Ana Maria Alviar , Kränkel Nicolle , Whitaker John , Dewhurst Mark , Maddedu Paolo , Paton Julian F.R.
Published: June 2021

Our evidence indicates that brainstem endothelium is a viable target for controlling arterial pressure. Thus, we have used EPCs to target the brainstem microvasculature in vivo and assessed any effect on cardiovascular function. Bone marrow mononuclear cells from male Wistar rats were expanded for 7–15 days in conditions appropriate for the endothelial lineage. EPCs were characterized by immunofluorescence staining, flow cytometry, and using the Matrigel assay for network formation. Fluorescently tagged EPCs were injected intraparenchymally into the nucleus tractus solitarii (NTS), a region regulating arterial pressure, of male Wistar rats. Experiments were terminated 16 days post‐injection. EPCs remained at the site of injection until animals were sacrificed. During this time, EPCs migrated away from the injection site becoming closely associated with the vasculature. Peak measurements occurred between 10 to 15 days post injection and included a reduction in: systolic pressure (SP)(−7±0.5 mmHg), low frequency spectra of SP (−19%±1.0‐ indicating reduced sympathetic vasomotor tone) and heart rate (−18±4.3 beats/min). Cardiac baroreflex sensitivity increased (22%±0.8). In conclusion, EPCs remain viable for at least 16 days when transplanted into the NTS in vivo, integrate into the vascular wall and alter cardiovascular autonomic function in normotensive rats.

MRC & Pfizer funded research.
Contributions of hydrogen sulfide to synaptic neurotransmission in the nucleus of the solitary tract (nTS) in normoxia and following chronic intermittent hypoxia
Authors: Austgen James R , Dantzler Heather A , Kline David D
Published: June 2021

Hydrogen sulfide (H2S) is a noxious gas generated through the metabolism of cysteine by cystathionine‐β‐synthase (CBS). Data show that at low concentrations H2S can serve as a neuromodulator to regulate neurotransmission. We examined if changes in neuronal nTS excitability following chronic intermittent hypoxia (CIH) may be due, in part, to an alteration in CBS expression or function. Rats exposed to 10 days of CIH were compared to normoxic controls. Immunohistochemistry examined CBS location and distribution. Immunoblot analysis of nTS and nodose ganglia tissue examined CBS protein levels. Changes in excitatory postsynaptic currents (EPSC) in nTS neurons were recorded in brainstem slices. Immunohistochemistry showed fibrous and somal immunoreactivity in the nTS in normoxia, and suggested an increase following CIH. CBS protein was elevated after CIH in the nTS and nodose ganglia, as detected by immunoblot. In control cells, exogenous H2S significantly increased amplitude and frequency of spontaneous (s)EPSC while depolarizing the cells. Though the CBS inhibitor aminooxyacetic acid (AOA) showed no significant effects on EPSCs in control cells, following CIH AOA significantly reduced sEPSC amplitude and input resistance, and hyperpolarized the cells. These data suggest CBS is upregulated following CIH, and endogenous H2S may have a role in excitatory neurotransmission in the nTS. Supported by HL085108
Hindlimb unloading results in loss of circadian control of heart rate and increased incidence of spontaneous ventricular arrhythmias
Authors: Welliver Kathryn C , Jepson Amanda J , Moffitt Julia A
Published: June 2021

Hindlimb unloading (HU) in rats, a model of cardiovascular deconditioning, has been found to result in cardiac sympathovagal imbalance. Previous data indicate that derangement in circadian control of heart rate may lead to increased risk for acute cardiac events via alterations in autonomic function. We hypothesized that attenuated circadian control of HR and increased incidence of spontaneous premature ventricular complexes (PVC) would occur over the course of 10–14 days of HU vs casted control (CC) condition. Radiotelemetry probes for electrocardiographic analysis were implanted in male, Sprague‐Dawley rats 10 days prior to manipulations. Data were collected for 5 consecutive minutes at the top of each hour, separated into light and dark cycles and statistically compared. Circadian differences in HR in CC (n=4) and HU (n=6) rats were similar and significantly different over 48h of baseline and 72h of HU adaptation. While loss of this difference and tachycardia occurred initially in both groups, HR and circadian control returned to baseline levels by 6 days in CC rats but not in HU rats. In addition, 27 spontaneous PVCs and one run of salvo were observed in a subset of HU rats (n=3) as compared to only 4 spontaneous PVCs in a subset of CC (n=2) rats. These data indicate that deconditioning leads to loss of circadian control of HR and increased incidence of ventricular arrhythmias, likely due to autonomic dysfunction.
Sympathetic overactivity in sinoaortic denervated C57BL mice
Authors: Rodrigues Fernanda L , Oliveira Mauro , da Silva Valdo J Dias , Salgado Helio C , Fazan Rubens
Published: June 2021

Male C57BL mice were submitted to sinoaortic denervation (SAD), or sham surgery, implanted with catheters into femoral artery and jugular vein and let recover for 5 days. After basal recording of arterial pressure (AP) and pulse interval (PI) mice received cardiac autonomic receptor blockers methylatropine or propranolol (n=8–11 in each group). PI changes due to methylatropine or propranolol were measured as cardiac vagal and sympathetic tone, respectively. AP variability was calculated by standard deviation of successive values (SDNN) of systolic AP and PI variability determined by SDNN as well as by the square root of the mean squared differences of successive values of PI (RMSSD). Mean AP and SDNN of SAP was higher in SAD (149±3 and 10.0±0.5 mmHg) as compared to intact mice (136±2 and 6.5±0.4 mmHg). PI was similar between groups (104±3 vs 104±2 ms) while SDNN and RMSSD of PI were lower in SAD (5.4±0.7 and 2.0±0.2 ms) as compared to intact mice (8.2±0.8 and 2.7±0.3 ms). Atropine did not change PI of SAD (100±4 to 98±4 ms), while slightly decreased PI of control mice (103±2 to 96±2 ms, p<0.05). The increase in PI elicited by propranolol was marked higher in SAD (98±6 to 144±9 ms) than in intact mice (98±4 to 124±3 ms). Five days after SAD mice showed mild hypertension with marked increase in AP variability and cardiac sympathetic tone.

Support: FAPESP, CNPq and CAPES.
Peripheral activation of ACE2‐Ang‐(1–7)‐Mas axis reduces the cardiovascular reactivity to acute stress in rats
Authors: Lima Augusto Martins , Xavier Carlos Henrique , Santos Robson Augusto Souza , Raizada Mohan K. , Ferreira Anderson J. , Fontes Marco Antônio Peliky
Published: June 2021

We recently reported that central activation of ACE2‐Ang‐(1–7)‐Mas axis markedly reduces stress‐induced tachycardia. In the present study we investigated the peripheral contribution of ACE2‐Ang‐(1–7) axis on the cardiovascular reactivity to acute stress exposure. Under tribromoethanol anesthesia, male Wistar rats (300g) received cannulas into femoral artery and vein for recording cardiovascular parameters and drugs injection, respectively. After 24h, Ang‐(1–7) [2.5nmol/Kg (n=8)], XNT, an activator of endogenous ACE2 [1μmol/Kg (n=6)] or saline [NaCl 0.9% (n=8)] were intravenously (i.v.) injected immediately before starting air jet stress (10 l/min‐10 min). Tachycardia evoked by air stress (Δ136±22 bpm) was greatly attenuated (P<0.05) by i.v. injections of Ang‐(1–7) (Δ61± 25 bpm), while XNT treatment changed the HR response to a bradycardia (Δ−44±7 bpm). These effects were observed throughout 10min stress trial. Heart rate during the post‐stress recovery period was also lower (P<0.05) in the groups treated with Ang‐(1–7) (412±20 bpm) and XNT (306±12 bpm), compared to vehicle (482±23 bpm). Changes (P<0.05) in blood pressure caused by air jet stress (Δ18±4 mmHg) were abolished by XNT (Δ−8±11 mmHg) and attenuated by Ang‐(1–7) (Δ9±3 mmHg). These current data extend our recent findings indicating that activation of ACE2‐Ang‐(1–7)‐Mas axis attenuates the cardiovascular reactivity to acute stress. Support CNPq and Fapemig.
A comparison of two radiotelemetry transmitters for the recording of behavioral and electrocardiographic data in prairie voles (Microtus ochrogaster)
Authors: Grippo Angela J , Allen Stephanie M , Chandler Danielle L , Dave Parag , McDaniel Vitoria , McNeal Neal
Published: June 2021

The prairie vole is reliant on its social context and is a useful model for studying behavioral and cardiac responses to social stressors. Prairie voles exposed to social isolation (vs pairing with a sibling) display increased behavioral and cardiac reactivity to stressors; elevated heart rate (HR); and reduced cardiac vagal control. We examine these changes using radiotelemetry technology (Data Sciences International; DSI); however, the size of the transmitter may confound valid and reliable data collection in prairie voles. In this study we tested the new DSI ETA‐F10 transmitter (vs ETA‐F20), to determine whether the smaller/lighter ETA‐F10 transmitter provides more reliable and valid behavioral and electrocardiographic (ECG) data. We assessed surgery parameters and variables associated with stressors in 6 adult prairie voles. Animals with ETA‐F10 transmitters (vs ETA‐F20) showed reduced surgery time (38 ± 3 min vs 63 ± 2 min); reduced recovery time to stable HR after surgery (10 ± 0 days vs 13 ± .5 days); reduced HR 10 days after surgery (367 ± 15 bpm vs 413 ± 9 bpm); reduced HR during a swim stressor (528 ± 3 bpm vs 572 ± 3 bpm); and improved swimming ability during a swim stressor. These preliminary data suggest that the ETA‐F10 transmitter produces more reliable ECG data and possibly less behavioral stress in prairie voles. Additional study of the ETA‐F10 transmitter is warranted. MH77581, NIU GC & CBBS, DSI.