bluuebunny/crossref_metadata_2025_split huggingface dataset:
DIY Video Laryngoscopy in Rats–Safe, Fast and Reliable
Authors: Balzer Claudius , Salzman Michele M. , Cleveland William J. , Riess Matthias L. 
Published: June 2021

IntroductionThe airway management of rats in the field of basic research is of great importance. Intubation is needed for general anesthesia, ventilation, and the use of neuromuscular blocking agents. For survival studies, especially, a less invasive intubation technique is preferred over tracheostomy. In the past, several different methods with high success rates have been described, but most need a high level of technical effort, training, and financial expenditure. In humans, video laryngoscopy for intubation is the most successful technique; it may also be feasible in rats with simple and cost‐effective devices.HypothesisBy using a commercial flexible video endoscope (VE), with small modifications for direct visualization, and the Seldinger‐Technique, intubation in rats can be quick, easy and reliable.MethodsA cost‐effective and waterproof VE (GiraffeCam, 5.5 mm diameter) with USB‐connection and an integrated light source was purchased. Due to its softness, and for fixation on the board, a 20 cm wire attached with surgical tape was added to the VE for more rigidity. After anesthesia was induced with an intraperitoneal injection of pentobarbital (45mg/kg), each rat was placed on its back on the board and fixed in position with surgical tape. The board was then secured in place on the bench at a 45° angle head up. The VE was hooked up to the board and connected to a computer. The tip of the VE was gently introduced into the mouth, on one side of the upper incisors, until the vocal cords could be identified on the video screen. A 14‐gauge catheter, used as endotracheal tube (ET), was prepared with a stylet (15 cm PE50 tubing) that was inserted and advanced 1 cm past the catheter tip. The ET was inserted into the trachea, and once past the vocal cords, the stylet was pulled back. One hundred (100) rats (30 Zucker Diabetic Fatty, 70 Sprague Dawley; weight between 350–450g) were intubated by this technique and used for experiments with cardiac arrest and resuscitation.ResultsAll intubation attempts were successful on the first attempt, with a proper placement of the ET. No complications, such as bleeding occurred, and all rats were ventilated without problems. Furthermore, this technique can be performed with little previous experience and in less than one minute.ConclusionWith estimated costs of approximately $30, this VL intubation procedure is a safe, fast and reliable technique for rat intubation.Support or Funding InformationDr. Balzer is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number 397561247. Additional support provided by institutional funds, NIH grant (5R01 HL123227), and a Merit Review Award (I01 BX003482) from the U.S. Department of Veteran Affairs Biomedical Laboratory R&D Service awarded to Dr. Riess.
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imageThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Both Dietary Salt Restriction and Excess Dietary Salt Intake Exaggerate Cardiovascular Reflex Responses to Activation of the Sciatic Afferents, Aortic Depressor Nerve, and Vagal Afferents
Authors: Katayama Pedro Lourenco , Wenner Megan M , Farquhar William B , Browning Kirsteen N , Stocker Sean D 
Published: June 2021

Excess dietary salt intake exaggerates sympathetic nerve activity (SNA) and arterial blood pressure (ABP) responses to several cardiovascular reflexes in salt‐resistant animals. Recently, observational cohort studies suggest that salt restriction increases cardiovascular morbidity/mortality in several cardiovascular diseases, and the relationship between cardiovascular morbidity and dietary salt intake resembles a J‐shaped curve. However, little evidence exists to document the impact of salt restriction on cardiovascular reflex responses and whether this relationship resembles a J‐shaped curve. Thus, the aim of the present study was to determine whether salt restriction affects SNA and ABP responses to activation of sciatic afferents, the aortic depressor nerve, and cervical vagal afferents. To address this hypothesis, male Sprague‐Dawley rats were fed low (0.01% NaCl, D17010, Research diets), normal (0.1% NaCl, D17020, Research Diets), and high (4.0% NaCl, D17013, Research Diets) salt diet for 14–21 days. Then, reflex responses were measured in Inactin‐anesthetized animals. Baseline mean ABP was not different across groups (low: 112±4, normal: 101±5, high: 109±3mmHg; P>0.1 overall ANOVA). Electrical stimulation of sciatic afferents (1ms pulse, 500uA, 5s duration, 2–20Hz) produced frequency‐dependent increases in ABP. Interestingly, the pressor response to sciatic nerve stimulation was significantly greater in rats fed low and high versus normal NaCl (5Hz; low: 22±4, normal: 12±2, high: 27±2 mmHg, n=5–10, P<0.05). Activation of the aortic depressor nerve (2ms pulse, 500uA, 15s duration, 2–20Hz) produced frequency‐dependent decreases in ABP. The depressor response to aortic nerve stimulation was significantly greater in rats fed low and high versus normal NaCl (5Hz; low: −29±6, normal: −11±3, high: −29±4 mmHg; n=3–7, P<0.05). Finally, electrical stimulation of the cervical vagal afferents (1ms pulse, 500uA, 5s duration, 2–20Hz) produced frequency‐dependent decreases in ABP. Again, the depressor response to vagal nerve stimulation was significantly greater in rats fed low and high versus normal NaCl (5Hz; low: −25±3, normal: −15±2, high: −29±2 mmHg; n=5–10, P<0.05). Simultaneous recordings of lumbar, renal, and splanchnic SNA followed the changes in ABP across low, normal, and high NaCl diets. The present findings showed that both dietary salt restriction and excess dietary salt intake exaggerates sympathetic and cardiovascular responses. These cardiovascular responses to activation of sciatic afferents, the aortic depressor nerve, and vagal afferents as a function of dietary salt resemble a J‐shaped curve.Support or Funding InformationNIH R01 HL128388 (WBF, SDS)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Microglia regulate RVLM‐projecting PVN neuronal activity
Authors: Shi Peng , Bi Qianqian , Wang Chao , Wei Bo , Shen Xiao Z , Liu Xiaoli , Gu Yan 
Published: June 2021

Microglia, the primary resident immune cells in the CNS, communicate with neurons very dynamically. Our previous studies show that activated microglia are involved in neurogenic hypertension. In the present study, we are investigating the mechanism by which microglia regulate RVLM‐projecting PVN neuronal activity in resting state. Adult male transgenic CD11b‐DTR mice were randomly assigned into two groups: sham control and diphtheria toxin (DT) groups, which received ICV infusion of saline or DT (depletion of microglia) respectively. Sympathetic neurons in the hypothalamic PVN are retrograde labeled by fluorescent microsphere from the brain stem RVLM. The electronic profile of RVLM‐PVN neurons are recorded in voltage clamp mode. Our results indicate that depletion of naïve microglia did not alter resting membrane potential nor membrane resistance. However, loss of microglia significantly inhibited outward potassium currents in RVLM‐PVN neurons. The frequency of mEPSP were also decreased in the PVN neurons in the absence of microglia. By confocal microscopy analysis, we found that there was a significantly decrease of spine density in the PVN neurons without microglia compared to the ones from the sham controls. Our results suggest that microglia directly regulate both intrinsic and extrinsic activities of the PVN sympathetic neurons.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Dynamics of Ventilatory Pattern Variability (VPV), Cardio‐Respiratory Coupling (CRC) and Cytokines in an E. coli Sepsis Model
Authors: Tackett Shiloh H , Solanki Neha , Nethery David E , Horton Kofi‐Kermit A , Bonfield Tracey L , Jacono Frank J , Dick Thomas E 
Published: June 2021

Cardio‐respiratory control is disrupted in sepsis. We hypothesized that increases in inflammatory cytokines that are expressed in the brainstem in a rat model of Escherichia coli (E. coli) peritonitis would correlate with decreases in VPV and the uncoupling of CRC. We implanted fibrin clots containing either 25×106 or 0 E. coli in the peritoneal cavity of chronically instrumented, adult Sprague‐Dawley Rats (n=19). We recorded cardiorespiratory patterns of awake, freely moving rats at 3, 6, 12, 24, and 48 hours after implantation. At each time point, blood, bronchoalveolar lavage fluid (BALF), peripheral and central nervous system (CNS) tissues were collected to measure cytokine concentrations. We quantified VPV and CRC using a set of complementary measures sensitive to both linear and nonlinear dynamics. We measured interleukin 1β (IL‐1b), interleukin 6 (IL‐6) and tumor necrosis factor α (TNF‐a) concentrations in serum, BALF and tissue supernatants by Luminex assay. Compared to the sham group, infected rats developed a systemic inflammatory response by 3h [increased serum IL‐6 (p<0.05), IL‐1b (p=0.05)], which peaked at 6h and then decreased progressively. Also, brainstem inflammation was evident at 3h post inoculation, with increases in IL‐1β in the medulla (p<0.01) and pons (p<0.05). Brainstem inflammation was associated with increased predictability in VPV, indicated by increases in mutual information (p<0.05) and nonlinear complexity index (NLCI). In our initial analysis of CVC (n=8 rats at 24h), the X2 values of the distribution of R‐wave timings relative to the onset of inspiration were highly significant but were not different between sham and septic groups. We conclude that decreases in VPV (i.e., increased pattern predictability) were present early in the course of systemic inflammation following E. coli infection in rats and these changes were associated with elevated serum and brainstem cytokines. In contrast, the persistence of CVC in the inoculated rats was unexpected; however, at 24h the NLCI was decreasing indicating that these rats may be recovering from the peritonitis.Support or Funding InformationVA Research Service (I01BX004197); NIH (U01 EB021960)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Modulation of mRNA Expression in Peripheral Tissue in a Rodent E. coli Sepsis Model
Authors: Horton Kofi‐Kermit A , Clifford Caitlyn , Tackett Shiloh H , Nethery David E , Dick Thomas E , Jacono Frank J , Strohl Kingman P 
Published: June 2021

The endogenous cannabinoid system (ECS) regulates cytokine production and mitigates pathophysiology in many pro‐inflammatory conditions, such as irritable bowel diseases, atherosclerosis and acute lung injury. Sepsis, a highly morbid condition, results from a dysregulated host response to infection. Despite extensive study the transcriptional regulation of cytokines and the ECS during sepsis remains to be established. We hypothesized that cannabinoid receptor (Cnr1 & 2) mRNA expression increases with systemic infection and these increases coincide with increases in pro‐inflammatory cytokines. We implanted a fibrin clot that contained either 25×106 or 0 E. coli in the peritoneal cavity of adult, male rats (n=8). Rats were euthanized at 3, 6, 12 or 24 h following the implant; lung, liver and serum were harvested. Total RNA was extracted using Trizol reagent, and cDNA was synthesized using reverse transcription PCR. Quantitative real‐time PCR was performed in duplicate for each sample using TaqMan Gene® Expression Assays specific for 18S ribosomal RNA (18S), Cnr1 & 2, interleukin (IL) IL‐4 & IL‐6 and tumor necrosis factor – alpha (TNF‐α). Each target gene was normalized to 18 S content, and relative quantitation of gene expression levels were performed using the comparative CT method (2−ΔΔCT method) with the 0 E. coli fibrin clot at each time point as the comparative control. The time course of cytokine expression depended on the cytokine and the tissue compartment. In liver, IL‐6 peaked at 3h (1086 ± 59% vs 0.36 ± 0.1%, p<0.01). In serum, IL‐4 peaked at 6h (168 ± 34% vs 86 ± 5%). In lung, both IL‐6 and TNF‐α expression levels peaked at 3h (IL‐6: 755 ± 33% vs 8 ± 0.5%, p<0.01; TNF‐a: 496 ± 230% vs 8 ± 0.2%); whereas, IL‐4 levels peaked at 24h (291 ± 31% vs 3 ± 2%, p<0.05). Interestingly, at 24h Cnr2 mRNA increased concomitantly with IL‐4 in the lung (360.0 ± 10% vs 30 ± 5%, p<0.01), whereas the expression levels of Cnr1 mRNA did not increase above sham surgical levels during the time course of this study. These preliminary data and analyses support our hypothesis that induction of ECS, as characterized by the increased transcription of Cnr2 mRNA, is associated with upregulation of mRNA of pro‐inflammatory cytokines.Support or Funding InformationNIH 5T32HL007913‐18, NIH U01 EB021960, VA Research Service I01BX004197This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Acid‐Sensing Ion Channels Blockade Attenuates Pressor and Sympathetic Responses to Skeletal Muscle Metaboreflex Activation in Humans
Authors: Fernandes Igor Alexandre , Campos Monique O , Mansur Daniel E , Mattos João , Paiva Adrielle , Videira Rogerio , Macefield Vaughan , Nóbrega Antonio CL 
Published: June 2021

In animals, the blockade of acid‐sensing ion channels (ASICS), cation pore‐forming membrane proteins located in the free nerve endings of group IV afferent fibers that are activated by acidic pH transients, attenuates reflex increases in sympathetic nerve activity (MSNA) and blood pressure (BP) during muscle contraction. These findings indicate that ASICS have an important role in mediating the metabolic component (skeletal muscle metaboreflex) of the exercise pressor reflex in animal models. Nonetheless, it is still unclear whether these findings can be translated to humans. We then tested the hypothesis that ASICS play a role in evoking the skeletal muscle metaboreflex in humans, quantifying beat‐by‐beat mean BP (MBP, Finometer), MSNA (peroneal nerve, microneurography) and heart rate (HR, ECG) in 11 healthy young men (N = 11) during rest, static handgrip exercise (SHE, 2 min at 35% of the MVC) and post‐exercise muscle ischemia (PEMI, 2 min) before (BFA) and after local infusion of amiloride (AFA −0.75 mg/mL), an antagonist of ASICs, in saline (2.5% of total forearm volume) via modified Bier block (regional intravenous anesthesia). In an additional protocol, participants (N = 7) underwent the experimental procedures before (BFS) and after (AFS) venous infusion of a similar amount of saline via modified Bier block. MBP responses were slightly but significantly attenuated during SHE after amiloride infusion (BFA +29.6 ± 6.1 vs. AFA +24.3 ± 7.0 mmHg, p = 0.001). A smaller increase in MSNA (N = 9) was also observed as a consequence of ASICs blockade (BFA +14.5 ± 9.6 vs. AFA +10.7 ± 6.5 bursts/min, p = 0.004). Equivalent SHE‐induced increases in HR were observed before and after ASICs blockade (p > 0.05). Amiloride infusion attenuated the PEMI‐induced increases in both MBP (BFA +25.8 ± 6.9 vs. AFA +16.3 ± 6.4 mmHg, p = 0.0001) and MSNA (BFA +16.2 ± 9.2 vs. AFA +8.4 ± 8.0 bursts/min, p = 0.0001). In the additional protocol, SHE‐evoked increases in MBP (BFS +28.7 ± 12.2 vs. AFS +27.0 ± 9.8 mmHg, p = 0.477), MSNA (N = 5, BFS +10.0 ± 8.6 vs. AFS +13.0 ± 9.4 burst/min, p = 0.208) and HR (BFS +32.0 ± 12.4 vs. AFS +37.2 ± 22.5 bpm/min, p = 0.265) did not differ before and after saline infusion. Similar observations were obtained for MBP (BFS +24.2 ± 14.2 vs. AFS +23.7 ± 10.4 mmHg, p = 0.830) and MSNA (BFS +10.0 ± 8.6 vs. AFS +13.0 ± 9.4 burst/min, p = 0.208) during PEMI. Therefore, these findings indicate that ASICs play a role in evoking pressor and sympathetic responses to both SHE and isolated activation of the skeletal muscle metaboreflex in humans.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Central Command, but not the Muscle Metaboreflex, is Responsible for Intensity‐Dependent Increases in Muscle Sympathetic Nerve Activity to Contracting Muscle during High‐Intensity Static Isometric Exercise in Humans
Authors: Boulton Daniel , Taylor Chloe , Green Simon , Macefield Vaughan 
Published: June 2021

Post‐exercise ischaemia has been used to demonstrate muscle metaboreflex‐mediated increases in muscle sympathetic nerve activity (MSNA) to an inactive limb during static isometric exercise. In contrast, we have previously shown a rapid centrally‐mediated increase in MSNA to a contracting leg during sustained isometric exercise, which promptly returned to resting levels at the cessation of exercise despite the presence of post‐exercise muscle ischaemia of the ipsilateral limb. However, these observations have been made during relatively low‐intensity exercise. The present study tested the hypothesis that central command, but not the muscle metaboreflex, increases MSNA to the contracting muscle during sustained isometric contractions even at higher intensities. MSNA was recorded continuously (microneurography) from the right common peroneal nerve. Twelve subjects (seven males, five females) performed two‐minute ankle dorsiflexions at 10, 20, 30, 40 and 50% of maximum voluntary contraction (MVC) ipsilateral to the MSNA recording, which was immediately followed by six minutes of post‐exercise ischaemia. There was at least six minutes rest between contractions. MSNA was analysed by measuring negative‐going cardiac‐locked sympathetic spikes from the raw neurogram. Compared with MSNA at rest (82 ± 5 spikes/min), MSNA to contracting muscle increased in an intensity‐dependent manner within one‐minute of contraction at 10 %MVC (145 ± 27 spikes/min, P=0.04), 20 %MVC (219 ± 28 spikes/min, P=0.002), 30 %MVC (480 ± 92 spikes/min, P=0.002), 40 %MVC (716 ± 185 spikes/min, P=0.01) and 50 %MVC (934 ± 275 spikes/min, P=0.02). Blood pressure increased in an intensity‐dependent manner during contractions up to 50 %MVC (76 ± 5 vs 93 ± 7 mmHg, P=0.02). Within one‐minute after each contraction MSNA returned close to resting levels even in the presence of post‐exercise ischaemia. These findings indicate that central command, and not the metaboreflex, is responsible for the increase in MSNA to contracting muscle during sustained isometric contractions, even at intensities up to 50% of MVC.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Muscle Sympathetic Nerve Activity and Vascular Conductance Responses at the Onset of Arm and Leg Exercise in the Inactive Limb
Authors: King Trevor J , Doherty Connor J , Millar Philip J 
Published: June 2021

Local mechanical and metabolic factors are known to regulate the blood flow response at the onset of exercise. However, little is known regarding the contribution of muscle sympathetic nerve activity (MSNA) to this onset blood flow response. The aim of the study was to examine the MSNA and vascular conductance response to exercise anticipation and onset in the inactive leg. Two identical visits were performed on 16 participants (n = 6 female). During visit 1, hemodynamic (Finometer) and MSNA (fibular nerve microneurography) measurements were acquired during rest (1‐minute), exercise anticipation (verbal preparation, 30‐seconds), and 1 minute of rhythmic handgrip (RHG, 1:1 duty cycle, 40% MVC) and one‐legged cycling (17 ± 3% peak power output). During visit 2, hemodynamic and superficial femoral artery (SFA) blood flow (Doppler ultrasound) measurements were acquired during the same exercise modes. Leg vascular conductance was calculated as SFA mean blood flow/mean arterial pressure. Total MSNA (burst frequency x burst area) was analyzed in 15‐second moving windows (5‐second progressions), and SFA blood flow was analyzed as 5‐second time bins aligned with the last 5 seconds of each MSNA moving window; both were expressed as relative change from baseline (%). Burst frequency, burst incidence, and total MSNA (height) followed the same pattern as total MSNA (area), and thus only total MSNA (area) is presented. Significance was set as p < 0.05, and data are mean ± SE. When participants were prompted to prepare for upcoming exercise (i.e. anticipation), total MSNA decreased from baseline prior to RHG (−40 ± 6%, p < 0.001) and cycling (−20 ± 6%, p = 0.03). During anticipation of RHG, this decrease in vasoconstrictor drive was followed 5 seconds later by a trend for increased SFA vascular conductance (+24 ± 12%, p = 0.07). At the onset of exercise, total MSNA decreased during RHG (−28 ± 6%, p = 0.002) and cycling (−39 ± 7%, p = 0.009). This was followed by an increase in SFA vascular conductance during both RHG (+34 ± 12%, p = 0.02) and cycling (+34 ± 20%, p = 0.005) conditions. In the absence of mechanical or metabolic factors in the inactive limb, these data suggest that a reduction in total MSNA can contribute to the exercise hyperemia that is observed at the onset of exercise. Furthermore, the anticipatory response of MSNA suggests a partial contribution of feedforward central command in this response.Support or Funding InformationNatural Science and Engineering Research Council of CanadaOntario Ministry of Research, Innovation, and ScienceCanadian Foundation for InnovationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Renal Sodium Excretion Consequent to Pharmacogenetic Activation of Gq‐DREADD in Principal Cells
Authors: Mironova Elena , Stockand James 
Published: June 2021

Stimulation of Gq‐coupled metabotropic P2Y2 receptors decrease the activity of ENaC in renal principal cells of the distal nephron. The physiological consequences of disrupting P2Y2 receptor signaling in the P2Y2 receptor knockout mouse are decreased sodium excretion and increased arterial blood pressure. However, because of the global nature of this knockout model, the quantitative contribution of ENaC and the distal nephron verses that of upstream renal vascular and tubular elements to changes in urinary excretion and arterial blood pressure are obscure. Moreover, it is uncertain whether stimulation of P2Y2 receptor inhibition of ENaC is sufficient alone to drive renal sodium excretion. Here we test the sufficiency of targeted stimulation of Gq signaling in principal cells of the distal nephron and P2Y2 receptors to increase renal sodium excretion using a pharmacogenetic approach and selective agonism of the P2Y2 receptor. Selective stimulation of the P2Y2 receptor with the ligand, MRS2768, decreased ENaC activity in freshly isolated tubules as assessed with patch clamp electrophysiology; and rapidly increased urinary sodium excretion as assessed in metabolic cages. Similarly, selective agonism with clozapine N‐oxide (CNO) of hM3Dq‐DREADD restrictively expressed in principal cells of the distal nephron decreased ENaC activity with consequent increases in sodium excretion. CNO when applied to control littermates failed to impact ENaC and renal sodium excretion. These studies represent the first use of the pharmacogenetics DREADD technology in the kidney; and demonstrate that selective activation of the P2Y2 receptor and Gq signaling in principal cells is sufficient to promote renal salt excretion.Support or Funding InformationThis research was supported by NIH/NIDDK grants R01DK98460, R01DK103758 and American Heart Association grant 17GRNT32920002 to JDSThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.