bluuebunny/crossref_metadata_2025 huggingface dataset:
Autonomic Nervous System and its Relevance in the Regulation of Heart Rate Recovery Post Exercise
Authors: Leon‐Ariza Henry Humberto , Botero‐Rosas Daniel Alfonso , Reyes‐Cruz Dario , Dussan‐Trujillo Maria Margarita , Maldonado‐Arango Maria Ines , Pulido‐Cardozo Laura Ximena , Zea‐Robles Aura Catalina
Published: June 2021

The recording of heart rate variability (HRV) is a strategy for the rapid and non‐invasive evaluation of the Autonomic Nervous System (ANS) activity. Previous studies have shown a rapid activation of the parasympathetic nervous system at the end of a physical effort and the association of this with the likelihood of developing cardiovascular disease.

PURPOSE

Establish the relationship between recovery heart rate (RHR) after exercise and HRV at rest in apparently healthy men and women.

METHODS

Quantitative, cross‐sectional, exploratory research conducted in 50 subjects (25 men and 25 women) of 19 ± 2.34 years. Subjects were monitored by continuous electrocardiographic reading all throughout the different activities. The HRV was evaluated at rest for 5 minutes, using time, frequency and non‐linear analyzes, cardiac vagal index (CVI) was calculated using Log10 (SD1*SD2). Subsequently, a physical test of 6 minutes on the bike was performed between 50 and 60% of the maximum reserve heart rate. In the end, the RHR was evaluated every 10 seconds during the first minute. Subsequently, the relationship between HRV and RHR was analyzed using the Pearson correlation coefficient (r).

RESULTS

In all population, mean HR at rest and RHR had an inverse effect, finding the following correlations: 10s (r = −0.35 p = 0.01), 20s (r = −0.37 p = 0.007), 40s (r = −0.40 p = 0.004) and 60s (r = −0.53 p = 0.000). Additionally, in women exist a direct correlation between RHR and CVI been more significant in the following correlations: 40s (r = 0.41 p= 0.044), 50s (r = 0.52 p= 0.008) and 60s (r = 0.59 p = 0.002); however, in men this correlation was not significant.

CONCLUSIONS

When performing stress tests in apparently healthy people, the decrease of the HR after exercise could be used to evaluate the activity of the ANS, specifically the activation of parasympathetic system demonstrated by the significant correlations between RHR and HR at rest, as well as the correlation between RHR and CVI. Therefore, the activity in the first minute after ceasing the exercise shows that the evaluation of the parasympathetic nervous system could be implemented in the early diagnosis and prognosis of chronic diseases including cardiovascular disease.

Support or Funding Information

The research was funding by the Faculty of Medicine of the Universidad La Sabana with the support of PROSEIM research group.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Validity of Stroke Volume and Cardiac Output Measurement between Finger Photoplethysmography and Continuous Wave Echocardiography during Treadmill Exercise in Adults with and without Down syndrome
Authors: Hibner Brooks A , Hilgenkamp Thessa I.M. , Schroeder Elizabeth C. , Lefferts Wesley K. , Fernhall Bo
Published: June 2021

Individuals with Down Syndrome (DS) have decreased aerobic capacity (VO2peak) and blunted fitness improvements with exercise training. Both decreased capacity and limited change is likely explained by autonomic dysfunction resulting in chronotropic incompetence. Increased stroke volume could potentially compensate for blunted heart rate increases and maintain cardiac output, however it is unknown if this occurs in those with DS. Therefore, it is important to accurately measure SV and Q during exercise to further evaluate limitations to peak aerobic capacity within this population. Stroke volume (SV) and cardiac output (Q) can be non‐invasively assessed during exercise via finger photoplethysmography (PPG) however this has not been validated in DS.

PURPOSE

Determine the concurrent validity of PPG, using continuous wave echocardiography (CWE) as the standard method, during exercise in adults with and without DS (control).

METHODS

Adults with DS (n= 6, 25 ± 2 yrs, 31.7 ± 4.6 kg/m2, 24.2 ± 4.2 ml/kg/min) and without DS (n= 5, 26 ± 4 yrs, 24.9 ± 4.8 kg/m2, 32.5 ± 6.4 ml/kg/min) performed a maximal incremental treadmill test to assess VO2peak. CWE images were captured at baseline, at each 2 minute exercise stage for 10 minutes and during recovery. PPG measurements were continuously obtained and then averaged over the last 30 seconds, matching CWE capture time points. Mean difference of combined time points between CWE and PPG was analyzed with t‐test and intraclass correlation coefficients (ICC absolute agreement) were computed between measurement methods for SV and Q. Validity based on ICC is considered poor: < 0.4, moderate: 0.5 – 0.75, or good: >0.75.

RESULTS

Mean difference (CWE‐PPG) between measurement methods in both SV and Q in controls was significantly different from zero (SV: −13.5 ± 23.86 ml p <0.01 and Q: −1.9 ± 2.9 L/min p <0.01) while no difference were evident in those with DS (SV: 0.7 ± 31.6 ml p =0.86 and Q: −0.4 ± 3.3 L/min p =0.33) The overall ICC for SV and Q was 0.543 and 0.712, respectively. Once separated by group, the ICC for SV in the control group was 0.760 and the DS group was 0.128. ICC between Q measures in control was 0.773 and in DS was 0.646.

CONCLUSION

Although PPG and CWE showed sufficient agreement between both SV and Q in individuals without DS, the absolute means were significantly different between methods. In individuals with DS, agreement between methods was low and moderate for SV and Q respectively, although the absolute means were not significantly different. Since the concurrent validity with CWE is not sufficient for PPG, we therefore recommend stroke volume measurement be obtained with CWE.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Fasting and Postprandial Trimethylamine N‐oxide in Sedentary and Endurance Trained Males
Authors: Steele Cortney , Baugh Mary Elizabeth , Griffin Laura , Neilson Andrew , Davy Brenda , Hulver Matthew , Davy Kevin
Published: June 2021

Background

Gut bacteria release trimethylamine (TMA) from dietary substrates, e.g., choline, phosphatidylcholine, and L‐carnitine. TMA is absorbed and subsequently oxidized in the liver to produce trimethylamine N‐oxide (TMAO). TMAO is associated with type 2 diabetes (T2D) and increased risk of cardiovascular disease. Consumption of a high fat diet (HFD) is associated with increase in TMAO in sedentary individuals. However, whether the increase in TMAO with consumption in a HFD is observed in endurance trained individuals is unknown.

Methods

Healthy, sedentary (n=17) and endurance trained (n=7) males consumed a 10‐day isocaloric lead‐in diet comprised of 55% carbohydrate, 30% total fat, <10% saturated fat prior to baseline testing. Blood samples were obtained in the fasting state and every hour during a 4‐hour high fat challenge (HFC) meal (820 kcal; 25% carbohydrate, 63% fat [21% saturated fat]) at baseline and following 5‐day HFD (30% carbohydrate, 55% total fat, 25% saturated fat). Plasma TMAO and TMA‐moieties (choline, betaine, L‐carnitine) were measured using isocratic ultraperformance liquid chromatography‐tandem mass spectrometry.

Results

Age (23±3 vs. 22±2.1 yrs) and body mass index (23.4± 3.0 vs. 23.5±2.1 kg/m2) were similar (both P>0.05) in the sedentary and endurance trained group, respectively. As expected, VO2max was significantly higher in the endurance trained compared with sedentary individuals (56.7±8.2 vs. 39.3±5.8 ml/kg/min). There were no significant differences in fasting (1.92 ± 0.8 μM vs. 2.09 ± 1.1 μM, P>0.05) or postprandial TMAO between sedentary or trained individuals, respectively, at baseline. Neither fasting (1.49± 1.2 μM vs. 2.25 ± 1.4 μM, P>0.05) or postprandial TMAO changed significantly with the HFD in the sedentary and endurance training individuals.

Conclusions

Neither fasting nor postprandial TMAO changed significantly following the HFD in the endurance trained compared to sedentary individuals in the present study. Future studies are needed to identify effective interventions that target TMA‐releasing bacteria and reduce TMAO.

Support or Funding Information

American Diabetes Association and Translation Obesity Research Interdisciplinary Graduate Education Program

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Age does not increase muscle fatigue resistance of the diaphragm
Authors: Fogarty Matthew J. , Mantilla Carlos B. , Sieck Gary C.
Published: June 2021

The diaphragm muscle (DIAm) comprises a mixed population of motor units, with FInt and FF units (type IIx and/or IIb fibers) vulnerable to sarcopenia ‐ age‐associated reductions of specific force and cross‐sectional area (CSA). Fatigue‐resistant S and FR units (type I and IIa fibers) are relatively spared. There is controversy as to whether aging confers an enhanced resistance to DIAm fatigue, with interpretations relying on relative measurements of force. We assessed the loss of DIAm force in 6‐ and 24‐month old Fischer 344 rats at 10, 40 and 75 Hz stimulation in 330 ms duration trains repeated each s (33% duty cycle) across a 2 min period. Although the initial specific force of the DIAm was lower in older rats across all stimulation frequencies, the final residual DIAm specific force after 2 min of stimulation was the same (~5 N/cm2) at all ages. This gave the misconception of an improved fatigue resistance, especially at 40 and 75 Hz. We also found that aging is associated with an increase in the relative contributions of type I and IIa fiber CSA to DIAm mass with decreased contributions of type IIx and/or IIb fibers. When these changing contributions are factored into a fiber type‐specific model of DIAm force generation, we found that ventilatory behaviors require activation of only type I and IIa fibers, regardless of age or fatigue. By contrast, the model predicts that aging impairs the ability of the DIAm to effectively perform expulsive manoeuvres, even in the non‐fatigued condition. In summary, relative fatigue measurements are not indicative of improved fatigue resistance in aging and are an artifact of reduced initial specific force contributions from FInt and FF units. These results are consistent with previous studies showing the relative vulnerability of FInt and FF units and conserved ventilatory behaviors in aging DIAm.

Support or Funding Information

R01‐AG044615

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Nitric oxide dependent delay in post‐fatigue contractile recovery in isolated fast‐twitch muscle: The role of the S‐nitrosoglutathione reductase
Authors: Gilmore Natalie K , Hogan Micheal C , Nogueira Leonardo
Published: June 2021

During fatiguing contractions, skeletal muscle fibers produce nitric oxide (NO) (and possibly S‐nitrosoglutathione (GSNO)) due to the activation of calcium‐calmodulin dependent NO‐synthases (NOS). Myofibers contain GSNO reductase (GSNOR), an enzyme that consumes GSNO, thereby controlling intracellular protein S‐nitrosylation. The present investigation tested the hypothesis that GSNOR scavenges the GSNO produced during repetitive contractions to protect contractile and calcium handling proteins from being S‐nitrosylated. To test this hypothesis, the effects of acute inhibition of GSNOR (GSNORi; SPL‐334, 10 μM) on contractility during and after fatiguing contractions in fast‐twitch muscle were examined. Extensor digitorum longus (EDL) muscles from both hindlimbs of mice (C57BL6/J; 8–9 weeks old) were dissected and placed in an experimental chamber for ex‐vivo isometric force measurements during electrical stimulation. For each mouse, one EDL was treated with the GSNORi, or L‐NMMA (L‐N‐monomethyl Arginine, a NOS inhibitor; 400 μM), or both, while the other EDL served as an untreated control. Muscles were repetitively stimulated at increasing frequencies until force was decreased to 30% of initial force. Contractile recovery from fatigue was determined at submaximal and maximal frequencies of stimulation for 120 min post‐fatigue. The treatment with either GSNORi or L‐NMMA did not change maximal or submaximal force development. Acute GSNORi incubation significantly decreased the force development during fatiguing contractions (~30% less force) compared to untreated muscles. During muscle recovery from fatigue in the untreated control muscle, force developed at low frequencies of stimulation was ~80% of pre‐fatigue values after 120 min of recovery. However, when GSNORi was present during fatigue and during recovery post‐fatigue, the force developed at submaximal and maximal frequencies of stimulation were both significantly impaired compared to control (to 55–70% of pre‐fatigue values after 120 min, P<0.05 vs control). The NO‐dependent effects of GSNORi incubation on post‐fatigue recovery were tested when L‐NMMA was present to block NO production. L‐NMMA completely abolished the delayed contractile recovery detected with GSNORi. These data suggest that fatiguing contractions increase NO production thereby enhancing the intracellular amounts of GSNO, which can negatively affect muscle recovery post‐fatigue when GSNOR is inhibited. These results indicate that GSNOR activity has an important role in protecting contractile function during stimulation patterns that lead to muscle fatigue.

Support or Funding Information

NIH (AR069577), CNPq (Universal)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effects of Gambogic Acid on the Production of Reactive Oxygen Species and Neutrophil Extracellular Traps
Authors: Reinke Julia Grace , Gardner Cole , Jackson Alexandria , Kumar Shaili , Petreaca Melissa
Published: June 2021

The innate immune system responds rapidly to the early signs of an infection or tissue damage by recruiting neutrophils to the affected area, where these inflammatory cells kill microbes through the production of reactive oxygen species (ROS) and neutrophil extracellular traps (NETs). Although these normal inflammatory responses are necessary for the elimination of potential pathogens before they proliferate and establish an infection, ROS and NETs are non‐specific mechanisms that can also damage host tissues. In chronic inflammation associated with various diseases, such as rheumatoid arthritis or Crohn's disease, prolonged or non‐resolving inflammation can cause severe pain and permanent tissue damage. We are currently investigating the potential of gambogic acid, a compound derived from the Garcinia hanburyi plant used in Ayurvedic and traditional Thai medicines, to reduce inflammation or promote its resolution. Previous studies have suggested that gambogic acid promotes apoptosis in multiple cell types, suggesting that this molecule could promote neutrophil apoptosis and thereby inhibit their inflammatory functions. In support of this hypothesis, we found that gambogic acid decreases PMA‐induced ROS and NETs by neutrophil‐like HL‐60 cells. Gambogic acid also decreases survival of neutrophil‐like HL‐60 cells in a WST‐8 survival assay, suggesting that it may reduce pro‐inflammatory neutrophil functions by inducing their apoptosis. We are currently investigating whether gambogic acid exerts similar effects on NET and ROS production in normal human polymorphonuclear cells (PMNs), and whether the gambogic acid impacts on neutrophil function are dependent upon its induction of neutrophil apoptosis. If so, this would suggest a therapeutic, inflammation‐resolving potential of gambogic acid in diseases characterized by excessive inflammation.

Support or Funding Information

DePauw University, Science Research Fellows

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Effect of TNF‐α on Mitochondrial Morphology in Model (NSC‐34) Motor Neurons
Authors: Brown Alyssa D. , Fogarty Matthew J. , Mantilla Carlos B. , Sieck Gary C.
Published: June 2021

Mitochondrial dysfunction and fragmentation precede neuronal death in many neurodegenerative disorders, including those involving motor neurons. In other cell types, pro‐inflammatory agents such as TNF‐α cause marked mitochondrial fragmentation. These inflammatory insults may underlie the vulnerability of specific neurons during age‐associated conditions, such as sarcopenia. We hypothesize that motor neuron exposure to pro‐inflammatory cytokines induces mitochondrial fragmentation. Experiments were conducted using a mouse motor neuron‐like cell line, NSC‐34. These cells were differentiated by serum depletion until neurite structures (>50 um) were observed, ~24 h. The differentiated NSC‐34 cells were then treated with mouse TNF‐α at varying concentrations; control (0 ng), 10 ng/ml, and 20 ng/ml for 24 h. The cells were then loaded with MitoTracker Green to image mitochondria using a Nikon A1R confocal microscope (60x oil immersion 1.4 NA). Images were analyzed using MatLab macro to calculate form factor, aspect ratio and mitochondrial volume density. TNF‐α exposure caused mitochondrial fragmentation as reflected by decreased form factor (27% reduction) and aspect ratio (12 % reduction). These results are consistent with inflammatory cytokine exposure leading to mitochondrial fragmentation in motor neurons which may increase their vulnerability mitochondrial dysfunction and cell death.

Support or Funding Information

NIH: RO1AG044615

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Oxidative Stress and Inflammation in Wound Repair: Molecular and Cellular Mechanisms
Authors: Pianissoli Lícia Gobeti , Silva Julia Paiva Rodrigues , Penteado Elis Arantes , Lopes Diana Ramlow Coelho , Mengal Vinicius Franskoviaky
Published: June 2021

Oxidative stress and inflammation are the critical factors attributed with delay in wound repairing process. Experimental studies established the dogma that inflammation is essential to the establishment of cutaneous homeostasis following injury, and in recent years information about specific subsets of inflammatory cell lineages and the cytokine network orchestrating inflammation associated with tissue repair has increased. Recently, this dogma has been challenged, and reports have raised questions on the validity of the essential prerequisite of inflammation for efficient tissue repair. Indeed, in experimental models of repair, inflammation has been shown to delay healing and to result in increased scarring. The main focus of present study was to explore the effect of oxidative stress and inflammation in the wound healing in patients with pressure injuries. The study was performed in patients in the medical clinic, from a general hospital, located in Espirito Santo‐Brazil. Weekly swab collection was performed in order to follow the healing process and therapeutic response. Molecular biology analyzes were performed to measure the presence increase, or time‐dependent reduction related to oxidative stress and inflammatory process. Our data show that pressure injuries in stages 2 and 3 of difficult healing present reduced of antioxidant enzymes, such as SOD and Catalase, as well as an increase in oxidant and inflammatory enzymes. We also evaluated the changes in inducible nitric oxide synthase (iNOS) and other inflammatory enzymes using western blot. Our results showed that, in pressure injuries, there is higher level of iNOS, inflammatory and oxidants enzymes. iNOS is linked to increased inflammation, leading to prolonged wound healing. Our results suggest that treatments that aim to reduce the local inflammatory process and consequently the oxidative stress can improve the healing process, as well as make the tissue repair process easier.

Support or Funding Information

This research was supported by a CNPq research grant. This study was funded by Fundação de Amparo a Pesquisa do Espirito Santo (FAPES‐Brazil) and Conselho Nacional de Desenvolvimento Científico e Tecnológico.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Nitric Oxide and Nitric Oxide Synthase isoforms are modulated in renal ischemia/reperfusion induced cardiac hypertrophy
Authors: Caio‐Silva Wellington , da Cruz Junho Carolina V , Panico Karine Cruz , Carneiro‐Ramos Marcela Sorelli
Published: June 2021

Introduction

It is known that kidney injury by ischemia/reperfusion (I/R) leads to cardiac hypertrophy mediated by immune system. Besides, the Nitric Oxide (NO) that can be produced by Nitric Oxide Synthase (NOS) plays a key role in cell signaling including heart and kidney. However, the role of NO and NOS, in pathophysiological cardiac hypertrophy caused by renal I/R has yet to be clarified. In this study, we begin to investigate the NOS expression and NO levels in kidney after I/R protocol.

Methods

C57BL/6 male mice were subjected to surgical occlusion of left renal pedicle for 60 min followed for reperfusion (I/R) for 8 and 15 days. Morphometric analyses were performed using as parameters kidneys weight and body weight, and vimentin mRNA as molecular kidney injury marker. Real time PCR was performed to analyze gene expression. To assess the bioavailability of NO in the form of S‐Nitrosothiols we use an amperometric protocol for S‐nitrosothiol with an NO specific sensor.

Results

The mRNA expression of all the three isoforms was analyzed in the left kidney. The expression of endothelial NOS and neuronal NOS were downregulated after 8 days of reperfusion (p<0.05) and returned to basal levels after 15 days. The induced NOS (iNOS) isoform followed the same pattern as the others at 8 days. However, the iNOS mRNA levels increased significantly after 15 days of reperfusion when compared to sham group (p<0.05). In relation to the bioavailability of NO in the form of S‐Nitrosothiols, the results showed that the left kidney 15 days I/R group presented a significant increase when compared to sham group. The right kidney presented no alteration on NO content.

Conclusion

These results showed that renal I/R induced renal damage leads to NOS modulation remarkably to iNOS expression at 15 days of reperfusion. This modulation can promote an increase on NO bioavailability and contribute to oxidative stress dysregulation. Data herein suggest a possible mechanism that contributes to cardiac hypertrophy developmental.

Support or Funding Information

Financial Support: FAPESP 2015/19107‐5

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Pendrin Mediates Bicarbonate Secretion and Enhances CFTR Function in Airway Surface Epithelia
Authors: Kim Dusik , Huang Junwei , Billet Arnaud , Abu‐Arish Asmahan , Goepp Julie , Matthes Elizabeth , Tewfik Marc A. , Frenkiel Saul , Hanrahan John W.
Published: June 2021

Bicarbonate facilitates mucin unpacking and bacterial killing however its transport mechanisms in the airways are not well understood. cAMP stimulates anion efflux through the CFTR (ABCC7) anion channel and this is defective in CF. The anion exchanger pendrin (SLC26A4) also mediates HCO3− efflux and is upregulated by proinflammatory cytokines. Here we examined pendrin and CFTR expression and their contributions to HCO3− secretion by human nasal and bronchial epithelia. In native tissue, both proteins were most abundant at the apical pole of ciliated surface cells with little expression in submucosal glands. In well‐differentiated primary nasal and bronchial cell cultures, IL‐4 dramatically increased pendrin mRNA levels and apical immunostaining. Exposure to low‐Cl− apical solution caused intracellular alkalinization (ΔpHi) that was enhanced 4‐fold by IL‐4 pretreatment. ΔpHi was unaffected by DIDS or CFTRinh‐172 but was reduced by adenoviral shRNA targeting pendrin. Forskolin increased ΔpHi and this stimulation was prevented by CFTRinh‐172 implicating CFTR, yet forskolin only increased ΔpHi after pendrin expression had been induced by IL‐4. The dependence of ΔpHi on pendrin suggests there is minimal electrical coupling between Cl− and HCO3− fluxes and that CFTR activation increases anion exchange‐mediated HCO3− influx. Conversely, inducing pendrin expression increased forskolin‐stimulated, CFTRinh‐172‐sensitive current by ~2‐fold in epithelial and non‐epithelial cells. We conclude that pendrin mediates most HCO3− secretion across airway surface epithelium during inflammation and enhances electrogenic Cl− secretion via CFTR as described for other SLC26A transporters.

Support or Funding Information

Support: Cystic Fibrosis Canada, Canadian Institutes of Health Research, Canada Foundation for Innovation

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Increased alcohol consumption and development of tolerance to alcohol‐induced sedation in NBCn1 knockout mice
Authors: Choi Inyeong , Schank Jesse R
Published: June 2021

The Na/HCO3 cotransporter NBCn1 plays a role in regulating synaptic pH. We recently reported that a human SLC4A7 gene polymorphism identified as a marker for polysubstance abuse is responsible for the production of a transporter variant that has a defect in function and expression. This finding prompted us to test whether NBCn1 is involved in alcoholism. Here, we examined alcohol‐drinking behaviors, as well as locomotor/anxiety and spatial learning behaviors, in NBCn1 knockout (KO) mice. In the open filed test, NBCn1 KO mice displayed decreased locomotor activity compared to wild type (WT) littermates. However, the activity in the elevated plus maze test was similar between WT and KO mice, indicating negligible change in anxiety. In the Morris water maze test, both groups of mice had learning behaviors improving each day with similar latency to escape in repeated trainings and distance traveled. The two groups learned the platform location with similar time spent in the trained quadrant during the probe trials. Thus, hippocampal‐based spatial learning was not altered in KO mice. Next, alcohol‐related behaviors were tested in a two‐bottle choice drinking experiment, in which mice were given to 3–15% ethanol with 3% increments at 4 days and alcohol consumption was measured. KO mice consumed more alcohol than WT mice with higher alcohol preference (p < 0.05). The consumption was also increased after repeated alcohol withdrawals. In the loss of righting reflex test following alcohol administration (3.5 g/kg alcohol; intraperitoneal), KO mice had a longer duration of sedation, but blood alcohol concentration did not differ. The duration became shorter when KO mice were pretreated with alcohol for 7 days, indicating the development of tolerance to the hypnotic effects of alcohol. Whole cell current clamp of hippocampal neurons showed that neurons from KO mice had a higher action potential threshold, no recurrent action potential, and a more depolarized membrane potential. These results indicate that abnormalities in NBCn1 alter alcohol consumption and alcohol‐related behaviors by changing neuronal excitability. Increased voluntary alcohol consumption in KO mice is probably driven by decreased rewarding value of alcohol. Neurons from KO mice are less excitable, which would lead to decreased neurotransmitter release. Thus, the rewarding value of alcohol is reduced, requiring more alcohol to achieve the same level of hedonic response.

Support or Funding Information

NIH and Emory URC

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Kölliker‐Fuse contains opioid‐sensitive inspiratory neurons and contributes to fentanyl‐induced apnea
Authors: Saunders Sandy E , Levitt Erica S
Published: June 2021

Opioid overdose deaths have rapidly increased largely due to illicitly manufactured fentanyl. The cause of death from opioid overdose is respiratory depression. Opioid‐induced respiratory depression is characterized by decreases in respiratory rate, chemoreceptor reflexes and impairment of the upper airway. The Kölliker‐Fuse (KF) regulates upper airway coordination and modulates respiratory rate. Opioid agonists in the KF reduce respiratory rate and cause apneusis. The influence of the KF during systemic fentanyl‐induced respiratory depression was investigated using the in situ arterially perfused working heart‐brainstem preparation of rat. Application of fentanyl to the preparation resulted in dose‐dependent slowing of rate, apneusis consisting of low‐amplitude phrenic nerve bursts and loss of post‐inspiratory vagal output, and eventually apnea with occasional low amplitude phrenic bursts. Subsequent application of CTAP, a mu opioid receptor antagonist, directly into the KF increased the frequency of low amplitude phrenic nerve bursting to a rate similar to baseline, with no change in vagal output. A similar pattern emerged with pre‐application of the mu opioid antagonist CTAP into the KF prior to systemic fentanyl administration. In separate experiments, KF neurons were recorded extracellularly before and after fentanyl administration. Inspiratory neurons stopped firing upon fentanyl administration, whereas, expiratory neurons continued to fire in the presence of fentanyl. These results suggest that opioid‐sensitive inspiratory neurons in KF may initiate low amplitude phrenic bursts and reverse fentanyl‐induced apnea.

Support or Funding Information

Funded by NIH Grant DA038069.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Development of a P2X2 Reporter Mouse Model
Authors: Kim Seol‐Hee , Taylor‐Clark Thomas
Published: June 2021

P2X2 is a ligand gated ion channel and purinergic receptor that is stimulated by adenosine 5′‐triphosphate (ATP). P2X2 is expressed in subsets of peripheral nerves and mediates various cellular responses in peripheral sensory nerve system. In particular, functional experiments have shown that P2X2 is selectively expressed in vagal afferents derived from the placodes (nodose ganglion) but not from the neural crest (jugular ganglion).

In this study, the Cre‐Lox reporter system was used to generate a mouse model enable us to target specific subtypes of sensory afferents. First, we generated a knockin P2X2‐Cre strain. Here a cre recombinase was incorporated into the endogenous P2rx2 gene, downstream of the last P2rx2 exon following a 2A sequence. Expression of Cre was linked to the expression of endogenous P2X2 via a 2A sequence. The P2X2‐Cre mouse was crossed with another strain carrying Floxed Ai9 ROSA tdTomato, which results in expression of tdTomato in only P2X2 expressing cells via Cre recombination. From these animals, sensory ganglia including vagal ganglia, trigeminal ganglia, superior cervical ganglia, carotid body and dorsal root ganglia were collected to visualize tdTomato‐expressing cells in combination with immunohistochemistry. Furthermore, brainstem was collected to map their central projections.

tdTomato positive cells were observed only in the nodose and not in jugular of vagal ganglia. Some population of cells showed tdTomato expression in trigeminal ganglia, dorsal root ganglia and superior cervical ganglia. In addition, strong tdTomato expression was observed in carotid body, which appeared to surround anti‐tyrosine hydroxylase positive cells and nerves. These results imply that P2X2 positive afferent nerves exist in different ganglia and therefore, ATP‐mediated purinergic signaling occurs in various peripheral sensory nerve systems. Lastly, tdTomato expression in sequentially sectioned medulla showed distinct patterns. The main area that has tdTomato expression is commissural nucleus of solitary tract (NTS), gelatinous NTS and dorsolateral NTS, as well as area postrema. This data suggests that the nodose‐originated sensory afferents project to specific regions of the medulla. Overall, the transgenic mouse model generated using Cre‐Lox system successfully labeled P2X2 cells.

Support or Funding Information

This study is funded by National Institutes of Health Common Fund SPARC OT2 (2016–2019): “Functional mapping of peripheral and central circuits for airway protection and breathing”

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Role of Vagal Pathways in the Respiratory Depressant Effect of Codeine on Breathing in the Anesthetized Cat
Authors: Rose Melanie J , Shen Tabitha Y , Musselwhite M Nicholas , Davenport Paul W , Bolser Donald C
Published: June 2021

A growing body of evidence indicates that systemic administration of centrally‐acting opioids can have actions on peripheral sensory receptors leading to complex effects on breathing. We speculated that the effects of systemically administered codeine on the breathing pattern would have a peripheral component. Experiments were conducted in anesthetized, spontaneously breathing cats (n=12). The animals were tracheotomized and electromyogram (EMG) electrodes were placed in the diaphragm to record inspiratory motor drive. The animals were allocated into two groups: vagal intact (VI) (n=5) or cervical vagotomy (CVx) (n=7). A dose‐response to intravenous codeine (0.1–10 mg/kg) was performed in each animal. Codeine elicited dose‐related decreases in respiratory frequency in both groups that were not significantly different from one another. This opioid also elicited dose‐dependent increases in diaphragm EMG magnitudes in both VI and CVx groups, but the change in EMG at the highest dose was significantly higher in the CVx group (change from control: CVx 189±43%; VI 40±21%, p<0.05). There was no significant difference in end‐tidal CO2 values suggesting that minute ventilation was similar between the two groups. These results support the hypothesis that codeine preferentially suppresses non‐diaphragmatic inspiratory motor drive in vagotomized animals, leading to larger compensatory increases in diaphragm activity than in vagal intact animals to maintain ventilation. An extension of this hypothesis is that vagal pathways maintain the excitability of intercostal and accessory inspiratory muscle motor drive with increasing doses of codeine.

Support or Funding Information

Supported by OT2OD023854‐01, HL131716.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Inspiratory Work, Power and Drive During Multiple Breath Extrinsic Resistive Loading in Healthy Adults
Authors: Davenport Paul Wesley , Davenport Matthew P. , Feinstein Justin , Khalsa Sahib , von Leupoldt Andreas
Published: June 2021

An extrinsic resistive load (R) to breathing increases the work of breathing. The extrinsic airway resistive work (W) of breathing during inspiration is defined as: Waw = Paw * Vi.. The power (J) required to breathe with this load is defined as: Jaw = ∫ Waw*dt. With increasing R, the Waw and Jaw required to sustain minute ventilation (VE) increases. The respiratory control system in the brainstem provides an inspiratory drive over the inspiratory duration (Ti) to generate sufficient inspiratory pump force to move the air through the airways and into the alveoli. The element of inspiratory drive required to compensate for increased extrinsic resistance is a function of the inspiratory Paw generated over the Ti, hypothesized as the pressure‐time‐product: PtP = ∫ Paw*dt. Thus, we predicted the PtP must increase with increasing Jaw as a function of the magnitude of the R. In addition, we reasoned that sustained breathing against increased R's require increasing PtP to compensate for the Jaw required to sustain VE. Hence, we hypothesized during a 10‐breath R loading trial, the PtP for Breath 10 will be greater Breath 1 as a function of R. Finally, we hypothesized that the perception of breathing effort is directly proportional to the PtP and Jaw. Healthy participants were tested while breathing through a non‐rebreathing circuit with inspiratory flow‐resistive loads (R=0, 5, 10, 25, 50, 100 cmH2O/L/s). The subjects inspired for 10 consecutive breaths for each load magnitude in a randomized block order. Subjects estimated their perceived load intensity (MEInt) and unpleasantness (MEUn) for breaths 1, 5 and 10. VE was unchanged for all 10 breaths with all R loads. The Waw and Jaw increased with increasing R. The PtP significantly increased with increasing R and was directly proportional to the increase in Jaw. The PtP increased from breath 1 to 10 only for R=100 cmH2O/L/s. The MEInt and MEUn increased with increasing R directly proportional to the PtP and Jaw. The results of this study demonstrate the increase Waw associated with breathing against extrinsic R loads increases the Jaw required to sustain VE. The PtP (drive) increases proportionately to the Jaw. The MEInt and MEUn increased with the increased PtP and Jaw generating an increased sense of breathing effort and negative affective perception for loaded breathing.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mitochondrial DNA damage associated activation of NLRP3 inflammasome impairs host defense during P. aeruginosa infection
Authors: Bedi Brahmchetna , Maurice Nicholas M , Yuan Zhihong , Prasla Zohra , Sadikot Ruxana T
Published: June 2021

P. aeruginosa is an opportunistic pathogen and a significant contributor of recalcitrant multidrug resistant infections. Immunocompromised and hospitalized patients are especially susceptible to rapid incessant infections. Therapies modulating innate immune defenses of the host are urgently needed for managing resistant infections. We have previously shown that the respiratory epithelium is an important contributor to host defense against P. aeruginosa and it's (quorum sensing) QS molecule N‐3‐oxo‐dodecanoyl‐L‐Homoserine lactone (C12‐HSL). Infection with PAO1 as well as C12‐HSL treatment induces mitochondrial DNA (mtDNA) damage. Emerging studies have shown that mtDNA acts as potential danger associated molecular patterns (DAMPs), which can in turn act as a driver of downstream inflammatory responses. We hypothesize that P. aeruginosa infection causes increase in mitochondrial membrane potential transition and ROS generation, causing release of damaged mtDNA in the cytosol as a DAMP. Presence of DAMPs in the cellular milieu activates TLR9 and the assembly and activation of the inflammasome mediated innate immune responses such as the secretion of IL‐1b and IL‐18. Exacerbation of inflammatory responses, attenuates host defense and enhances infection susceptibility. Normal bronchial epithelial (BEAS‐2B) cells infected with multiple P. aeruginosa strains, namely PAO1, PA1O3 and PAK showed a significant increase in the mRNA and protein expression of NLRP3, AIM2, nod like receptors (NLRs) and the other components of the inflammasome complex. This increase in expression was concomitant with the increase mtDNA damage. An increase in Toll like receptor 9 expression was also noted in the P. aeruginosa infected BEAS‐2B cells. The functional impact downstream of these interactions is the reduction in expression of epithelial immune mediators such as anti‐microbial peptides (AMPs) including human beta defensin (hBd2) and cathelicidin (LL37) as well as loss of epithelial barrier integrity. Studies exploring the inhibition of NLRP3 inflammasome using compounds such as Glibenclamide are currently underway and can be exploited as a therapeutic target to enhance host defenses

Support or Funding Information

Department of Veterans Affairs 2I01BX001786 (RTS)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Long Term Hypoxia Reduces Antioxidant Levels and Causes a Glycolytic Shift in Neonatal Sheep Pulmonary arteries
Authors: Kafeero Isaac , Alvarez Rafael , Lopez Vanessa , Bosviel Remy , La Frano Michael , Newman John , Fiehn Oliver , Zhang Lubo , Wilson Sean M
Published: June 2021

Gestational Hypoxia is a common prenatal stress caused by high altitude living, smoking, and other prenatal disorders. Such hypoxic insult can cause abnormalities in lung development that result in pulmonary hypertension in the newborn. Hypoxia is known to cause oxidative stress and accentuate glycolysis in adult tissues, effects which are intertwined with the development of various diseases. However, the adaptive responses of metabolism to long term hypoxia (LTH) in the fetal pulmonary vasculature is not nearly as well understood. The current work tests the hypothesis that following gestational LTH there is reduced antioxidant capacity and increased cellular glycolysis in neonatal sheep. For this study, normoxic pregnant and non‐pregnant sheep were obtained from Nebeker Ranch in Lancaster, CA (~700 meters) and were either sent to Loma Linda for study or to the White Mountain Research Station at an altitude of 3800 meters to induce LTH. After 110+ days at high altitude, animals were transported to Loma Linda University for the study. Pulmonary arteries of adult, 2‐week‐old newborn, and near‐term fetal sheep were isolated and frozen for analysis of primary metabolites. Metabolite levels were analyzed using Gas Chromatograph Time of Flight mass spectrometry (GC‐TOF MS) and visualized using enrichment and pathway analyses. LTH decreased the concentration of the antioxidant glutathione (GSH) and increased lactic acid, a byproduct of glycolysis, in adult and fetus. In the newborn LTH also decreased citric acid, a key intermediate in the Krebs cycle. These data indicate that the mother does not protect the pulmonary vasculature of the fetus from long term hypoxic stress due to gestation at high altitude. Thus, the fetus appears to be vulnerable even at modest altitudes to metabolic shifts and oxidative stress. Effects of these metabolic changes may persist after birth and contribute to the development of disease in the neonate or later in life.

Support or Funding Information

This material is based upon work supported by NIH grants P01HD083132 (LZ) and 1U24DK097154 through a pilot project grant to SMW as well as P20MD006988. IK was an Undergraduate Summer Research Fellow while RA was an Apprenticeship Bridge to College Scholar through the Center for Health Disparities and Molecular Mechanisms at Loma Linda University. VL is a recipient of the American Physiological Society's Short‐Term Research Education Program to Increase Diversity in Health‐Related Research (STRIDE) Fellowship funded by the APS and a grant from the National Heart, Lung and Blood Institute R25HL115473.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Oxidative deregulation of ferrochelatase mediates transferrin receptor‐induced remodeling in pulmonary arterial smooth muscle cells in monocrotaline‐induced pulmonary arterial hypertension
Authors: Alhawaj Raed , Ghadhanfar Elham , Cherian Susan
Published: June 2021

Pulmonary arterial hypertension (PAH) is driven by pulmonary arterial smooth muscle cell (PASMC) vasoconstriction and remodeling. One of the many drivers of PAH‐PASMCs remodeling is increased transferrin receptor‐1 (TFR‐1) expression. Under pro‐PAH conditions, PASMCs exhibit elevated reactive oxygen species (ROS) production which may disrupt ferrochelatase normal heme production. We evaluated the role played by ROS‐deregulated ferrochelatase in TFR‐1‐mediated PAH‐PASMCs remodeling. Intra‐lobar pulmonary arteries (PA) isolated from monocrotaline‐induced PAH model in Sprague‐Dawley rats have shown an up‐regulation of ferrochelatase expression, that can be a result of hypoxia‐inducible factor (HIF) mediated up‐regulation to compensate for decreased ferrochelatase catalytic activity. Decreased ferrochelatase activity was evident in the decreased levels of hemin (oxidized form of heme) in isolated PAH‐PAs. Endothelin‐1 (ET‐1), which is an inducer of mitochondrial ROS and is one of the mediators of PAH; was used in a 24‐hour organ culture of isolated endothelium‐removed bovine pulmonary arteries (BPA). ET‐1 cultured BPAs have shown decreased hemin levels and increased TFR‐1 expression. Thus, ROS‐deregulated ferrochelatase may promote vascular remodeling in PAH through the impairment of hemin‐mediated downregulation of TFR‐1 receptors in PASMCs.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Intermittent Hypoxia Disrupts Synaptic Long Term Depression
Authors: Arias Alejandra , Nwakudu Chinwendu , Khuu Maggie A , Garcia Alfredo J
Published: June 2021

Long term potentiation (LTP), activity‐dependent synaptic strengthening, and long term depression (LTD), activity dependent synaptic attenuation, are two forms of synaptic plasticity whose underlying mechanisms permit flexibility in synaptic communication and serve as substrates for learning and memory. Intermittent hypoxia (IH), a hallmark of sleep apnea, is known to impair spatial learning and memory. The objective of this study is determine how LTP and LTD are affected by IH. We hypothesize that IH impedes efficacy of activity dependent synaptic plasticity in the hippocampus, a brain structure important to learning and memory. We examined in vitro LTP and LTD in hippocampal brain slices following IH exposure. Electrophysiological recordings showed that LTP in area CA1 could be evoked in control and IH exposed groups, yet the magnitude of LTP following IH was decreased (LTP: control 184.72±15.93% vs. IH 145.35±6.34% baseline) . While LTD could be elicited in the control group (63.31±3.03% baseline), LTD could not be evoked from the IH exposed group (104.18±3.44% baseline). Although IH impacted both forms of long term synaptic plasticity, this was not accompanied by differences in paired‐pulse facilitation, indicating that short‐term plasticity was unaffected by IH. These findings demonstrate that IH affects mechanisms of activity‐dependent regulation of synaptic efficacy, which may involve IH‐dependent changes in NMDA receptor contribution to these phenomena. Our findings further contribute to understanding potential neurophysiological changes that may decrease the threshold for cognitive decline associated with sleep apnea.

Support or Funding Information

This work was supported by NIH R01 NS10742101 (AJG).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.