bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneous endothelial Ca2+ signal modalities in wild type and TRPC4 knockout rats in pulmonary arterial hypertension (1176.4)
Authors: Francis Christopher , Xu Ningyong , Taylor Mark , Zhou Chun , Alexeyev Mikhail , Stevens Troy 
Published: June 2021

Pulmonary arterial hypertension (PAH) is a deadly disease characterized by high pulmonary arterial pressure, and there are currently no effective treatments. Recently, our lab found that rats genetically lacking the canonical transient receptor potential channel 4 (TRPC4), a Ca2+‐permeable channel, exhibit a survival benefit in a model of PAH. Here we tested the hypothesis that heterogeneous endothelial Ca2+ signaling modalities exist in wild type and TRPC4 knockout rats, and that these modalities are altered in PAH. We compared the cytosolic endothelial Ca2+ activity of wild type and knockout rats in both normal and PAH conditions using opened artery preparations and confocal microscopy. We found that the amplitude of basal endothelial Ca2+ activity was significantly greater for knockout (mean F/F0: 1.46) than for wild type (mean F/F0: 1.11) rats. Additionally, both genotypes exhibited considerable Ca2+ signal heterogeneity within opened artery segments, which was altered in response to PAH. Furthermore, we found that Ca2+ responses to Acetylcholine were significantly truncated in knockout (mean duration: 9.69 s) compared to wild type (mean duration: 26.7 s) rats. We conclude that heterogeneous Ca2+ signaling modalities exist in the endothelium of wild type and TRPC4 knockout rats, and that these modalities are altered differentially in PAH. This phenomenon may be a key determinant of PAH mortality.Grant Funding Source: HL66299, HL60024
Mesenchymal stem cell expressed VEGF‐E protects pulmonary endothelial cells from cigarette smoke toxicity (1176.9)
Authors: Zhai Bo , Zhang Li , Huang Chaoqun , Varshney Rohan , Sivasami Pulavendran , Hinsdale Myron , Liu Lin , Lloyd Pamela 
Published: June 2021

Chronic obstructive pulmonary disease (COPD) is a major public health problem worldwide and the fourth leading cause of mortality in the US. COPD patients have compromised lung microvascular endothelial cells (EC) and decreased lung capillarity. Vascular endothelial growth factor (VEGF), a critical survival factor for EC, is reduced in lungs of COPD patients. Mesenchymal stem cells (MSC) are adult stem cells which secrete paracrine cytoprotective factors, including VEGF‐A. However, VEGF‐A is active at both VEGFR‐1 and VEGFR‐2, and VEGFR‐1 is implicated in the pathogenesis of COPD. Thus, we hypothesized that selective VEGFR‐2 activation would better protect lung EC from cigarette smoke induced damage in vitro. VEGF‐E, a VEGFR‐2 selective viral isoform, was expressed using a lentiviral vector in MSC isolated from bone marrow of C57BL/6 mice. Conditioned medium from wtMSC and VEGFE‐MSC was collected and concentrated 10‐fold. Primary human lung microvascular EC (HLMVEC) were then exposed to cigarette smoke extract (CSE,10%) ± wtMSC or VEGFE‐MSC conditioned medium (CM). HLMVEC treated with VEGFE‐MSC CM showed increased viability (MTT assay; absorbance at 570nm 0.295±0.073) after 24 h of CSE exposure , compared to wtMSC CM treated CSE‐exposed HLMVEC (absorbance 0.085±0.031, p<0.001).We next will compare the effects of VEGF‐A and VEGF‐E on endothelial permeability using a fluorescent dextran assay to determine whether VEGF‐E is less likely than VEGF‐A to cause increased permeability in vitro and edema in vivo. Studies to further characterize the effects of VEGFE‐MSC CM on EC in vitro are underway. Future studies will examine the ability of VEGFE‐MSC to repair the injured lung in COPD.Grant Funding Source: Supported by Oklahoma Center for Adult Stem Cell Research
Impaired arousal associated with prenatal alcohol exposure in rat pups is related to an increase in brainstem GABA (1177.5)
Authors: Sirieix Chrystelle , Wrocklage James , Schneider Robert , Darnall Robert 
Published: June 2021

Prenatal alcohol exposure (PAE) increases the risk for The Sudden Infant Death Syndrome (SIDS). Many SIDS infants are exposed to repeated hypoxia before death. Arousal in response to hypoxia is impaired after PAE and is modulated by medullary raphe GABAergic mechanisms. We therefore hypothesized that arousal impairment after PAE would be associated with increases in medullary GABA. Pregnant dams received an ethanol liquid diet (ETOH), an iso‐caloric pair fed diet (PF) or a standard chow diet (CHOW). Artificial cerebrospinal fluid (ACSF) or nipecotic acid (NIP), a GABA reuptake inhibitor, was microinjected (50 nL) into the raphe magnus (RMg) of P15 and P21 pups from each diet group. After recovery, pups were exposed to 4 episodes of hypoxia and the time to arousal (latency) was determined behaviorally. Brainstem GABA concentration was measured (HPLC) in P5, P15 and P21 pups from each diet group. At P21, ACSF injected pups in the ETOH group had longer arousal latencies than those in the PF and CHOW pups combined (CON group) (P<0.001). ETOH pups also had higher brainstem GABA concentrations (P=0.013). Moreover, CON pups injected with NIP had arousal latencies similar to those in ETOH pups after ACSF injection and NIP injected ETOH pups had no further increases in arousal latency. Our results show that the effects of PAE on arousal are associated increases in brainstem GABA and that RMg GABA reuptake mechanisms may be involved.Grant Funding Source: Supported by NIH PO1 HD36379 and R21 AA020279
Arousal from sleep produced by optogenetic stimulation of C1 neurons is reduced following sleep deprivation or hypoxia, but restored with systemic adenosine 1A antagonism (1178.11)
Authors: Burke Peter , Guyenet Patrice 
Published: June 2021

Arousal from sleep is the major defense mechanism against asphyxia and is sensitive to environmental stressors. Here we determined whether sleep deprivation or hypoxia reduces the probability of arousal from sleep and cardiorespiratory activation by optogenetic stimulation of C1 neurons in freely‐behaving rats. Channelrhodopsin‐2 was selectively introduced into C1 neurons of Tyrosine Hydroxylase Cre‐driver rats with a Cre‐dependant viral vector. Sleep stages were identified from EEG and neck EMG recordings. Breathing was measured using whole body plethysmography and blood pressure by telemetry. During non‐rapid eye movement sleep, unilateral photostimulation of C1 neurons produced arousal in 86 ± 5% of trials and sighs in 65 ± 7% of trials (n=5). After sleep restriction (6am ‐ 12am), incidence of arousal and sighs were significantly reduced to 37 ± 3% and 28 ± 2% (n=4), respectively, though cardiorespiratory responses remained unchanged. A hypoxic insult (12% O2 for 30min) also reduced arousals and sigh in subsequent trials to 28 ± 4% and 18 ± 6%, respectively (n=5), but caused no change in cardiorespiratory activation. The impaired arousal and sigh incidence in both stressor models were fully restored with an adenosine 1A receptor blocker (DPCPX; 0.2 mg/kg ip), suggesting that an increase in adenosine inhibitory tone selectively depresses the wake‐promoting responses to C1 neuronal activation.Grant Funding Source: Supported by NIH (HL28785, HL74011)
Coordination of swallow and breathing: in vivo and computational model simulations (1178.12)
Authors: Pitts Teresa , Gestreau Christian , Morris Kendall , Lindsey Bruce , Davenport Paul , Bolser Donald 
Published: June 2021

Coordination of swallow and breathing is vital for airway protection. However, the central mechanisms for the coordination of these behaviors are not known. We speculated that coupled oscillators could be used to explain swallow‐breathing interactions. In vivo recordings in anesthetized cats (n=6) demonstrate that swallow exhibits respiratory phase preference with 83% during expiration (E), 7% during inspiration (I), and 10% phase transition. A swallow oscillator circuit with two, mutually inhibitory, neuron populations, (A &amp; B) was added to the extant medullary breathing network. The swallow A group excites downstream motoneurons and the swallow B group controls inter‐swallow duration. To loosely couple the oscillators excitatory connections were added: 1) I populations to swallow B, controlling swallow occurrence during E phase; 2) E‐augmenting population to swallow B, increasing the probability of swallow occurrence near the end of E. Additionally, to reduce expiratory activity during swallow, an excitatory connection was added between the swallow A population and an E decrementing population, which in turn suppressed E‐Aug bulbospinal activity. Simulations exhibited repetitive breathing, and swallow occurred during the appropriate breathing phase. We conclude significant features of the swallow‐breathing relationship can be modeled with loosely coupled oscillators. NIH HL89104, HL103415, HL89071, HL109025, HL 111215(K99/R00)Grant Funding Source: NIH HL89104, HL103415, HL89071, HL109025, HL 111215 (K99/R00)
Effects of hypothyroidism in female hamsters on D1 receptor modulated breathing and expression of D1 receptors (1178.2)
Authors: Schlenker Evelyn , Del Rio Rodrigo , Schultz Harold 
Published: June 2021

The D1 receptor antagonist, SCH23390 (SCH), decreased ventilation (VE) in euthyroid (E) male hamsters exposed to air and hypoxia, but increased VE in hypothyroid (H) hamsters exposed to air, but not during hypoxic exposures. In H relative to E males, D1 receptor expression was decreased in the carotid body (CB), striatum, and paraventricular nucleus of the hypothalamus (PVN), but not in the nucleus tractus solitarius (NTS). For the present study we hypothesized that in H female hamsters D1 receptor expression in the CB, PVN, NTS and striatum and modulation of breathing would be dissimilar to that observed in H males. H and E female hamsters received SCH or saline. Physiological parameters were evaluated in awake animals exposed to air, 5 minutes of hypoxia (10% O2 in N2) and then air. SCH decreased body temperatures in both groups, had no effect on metabolism, but VE was increased in the H hamsters relative to E hamsters’ responses during air and hypoxic exposures due to increased tidal volumes. SCH relative to saline decreased breathing frequency, but increased tidal volume in the E hamsters during baseline and post‐hypoxic air exposures. In both groups SCH decreased hypoxic responsiveness. Expression of D1 receptors was similar in both groups in all regions. Thus, the ventilatory responses in H females were similar to SCH relative to H males (but not in E males), expression of D1 receptors was dissimilar in 3 regions.Grant Funding Source: Internal Sanford School of Medicine Grant
Attenuation of pulmonary chemoreflex following acute cervical spinal cord injury (1178.4)
Authors: Tsai I‐Lun , Lee Kun‐Ze 
Published: June 2021

Pulmonary C‐fibers are the main chemosensitive afferents in the lung. Activation of pulmonary C‐fibers can evoke pulmonary chemoreflex characterized by apnea, hypotension and bradycardia which is a critical defense reflex to modulate cardiorespiratory responses. The present study was designed to investigate whether pulmonary chemoreflex is altered following acute cervical spinal injury. Adult Sprague Dawley rats received high cervical unilateral hemisection (C2Hx) or C2 laminectomy (sham) were used. Intra‐jugular capsaicin induced pulmonary reflex was evaluated by measuring respiratory airflow in spontaneously breathing rats and phrenic nerve activity in mechanically‐ventilated rats. Capsaicin treatment evoked a cessation of respiratory airflow and phrenic bursting in sham but not C2Hx animals. In order to clarify whether attenuation of pulmonary chemoreflex in C2Hx animals is merely induced by capsaicin or generally applied to other stimuli that can excite pulmonary C‐fibers, another pulmonary C‐fiber stimulant (phenylbiguanide, PBG) was used to evoke pulmonary chemoreflex in spontaneously breathing rats. We observed that PBG‐induced pulmonary chemoreflex was also blunted in C2Hx animals. These results suggested that pulmonary chemoreflex is attenuated after acute C2Hx and the blunted reflex may unfavorably impact the ability to prevent inhaling respiratory irritants.Grant Funding Source: Supported by NSC 102‐2320‐B‐110‐004‐MY3, NHRI‐EX102‐10223NC
Mechanosignaling with ischemia‐reperfusion: restart of flow triggers a signaling cascade (1180.11)
Authors: Abe Shigeru , Tao Jian‐Qin , Wang Hui , Hong Nankang , Hood Elizabeth , Feinstein Sheldon , Cantu Edward , Christie Jason , Fisher Aron , Chatterjee Shampa 
Published: June 2021

We concluded earlier that endothelial mechanotransduction with ischemia in the lung activates a signaling cascade comprised of KATP channel closure that leads to NOX2 activation and reactive oxygen species (ROS) production. We studied the mechanosignaling with reperfusion. Isolated perfused mouse lungs and pulmonary endothelial cells showed a 2 fold increase in ROS production with ischemia that increased by 3‐3.5 fold upon reperfusion. This response is not due to hypoxia or reoxygenation since alveolar pO2 is unchanged in these ventilated lungs. ROS production was not observed in lungs and cells from NOX2 null, KATP channel null mice or lungs pre‐treated with KATP agonist (cromakalim) or a NOX2 activation inhibitor (MJ33). Wild type mice (WT) showed ~1.8 fold increase in oxidative lung damage (as assessed by 8‐isoprostanes, TBARS, alveolar permeability) with pulmonary ischemia and a ~2.5 fold increase with reperfusion; no significant change was observed in NOX2 null mice. Calcium influx, observed with ischemia in WT cells increased further with reperfusion; this was not observed in KATP and NOX2 null cells. Reperfusion thus amplifies the effects of the mechanosignaling cascade that is associated with ischemia. Prevention of the cascade with inhibitors such as MJ33 or cromakalim has potential application in lung transplantation which requires reperfusion of a previously ischemic lung.Grant Funding Source: NIHRO1HL‐075587
Pinhão‐manso (Jatropha curcas) demonstrates potent antibacterial properties in a rat model of third degree burns (1180.18)
Authors: Paulillo Luis , de Sousa Lessa Gladssinay , Isaacson Janalee , Mo ChengLin , Brotto Leticia , Abreu Eduardo , Brotto Marco , Gomes Mourão e Lima Januario 
Published: June 2021

Pinhão‐manso (Jatropha curcas L.; JC) is multipurpose perennial plant native from Brazil that belongs to the Euphorbiaceae family. This plant has mainly been considered for its potential as an alternative source of fuel. We recently demonstrated that JC has very potent protective activity against the toxic effects of ethanol in both tenocytes and muscle cells. Here we employed a rat model of 3rd degree burn to compare the effects of JC with silver sulfadiazine (SS). Microbiological analyses were conducted 1, 7, and 21 days after localized burn was induced. We found that at Day 1, all experimental groups presented with the same type of bacteria in their burns. During the course of these observations it make evident that there was significant reduction of bacterial infection in the group treated with JC as compared with the group treated with SS. The morphological appearance of the burns in JC treated group was also improved as compared to JC. Our new results suggest that JC has anti‐bacterial actions that could be further explored for medicinal use.Grant Funding Source: Supported by Conselho Nacional de Pesquisa (Brazil), CAPES (Brazil) and the Thompson Endowment Fund
Real‐time monitoring of oxygenation in cultured organotypic brain slices (1180.20)
Authors: Dmitriev Ruslan , Borisov Sergey , Kondrashina Alina , Pakan Janelle , Papkovsky Dmitri 
Published: June 2021

Cultured brain slices are important models in studies of brain development, regeneration of neural tissue upon (patho)physiological conditions and development of novel tissue remodeling systems. Efficient control of temporal and spatial oxygenation in such models is indispensable. We have developed novel phosphorescent O2 probe MM2X, which allows efficient in‐depth intracellular staining of neural tissue (~50‐100 μm, 2‐3 h) and imaging in different modalities (one‐, two‐photon, intensity, PLIM), over the range of 0‐200 μM of O2. We found minimal probe toxicity upon staining and imaging (analysis of membrane integrity, polarization of mitochondria and endocytosis), while its spectral properties allow multiplexing with conventional fluorescent markers such as GFP. We investigated staining efficacy of brain slices of different age (E12‐P21) and found a modest decrease in adult tissue. In proof‐of‐concept study, we analysed brain tissue oxygenation and correlated it with the distribution of BLBP‐GFP‐positive cells and glial progenitor cells. After culturing at 1‐3DIV, brain slices displayed high spatial heterogeneity (50‐150 μM) and no correlation between O2 and BLBP distribution. This study demonstrates how O2 imaging can be combined with the study of processes of neurogenesis in complex 3D models of developing tissue.Grant Funding Source: Supported by the Science Foundation Ireland.
Regulation of epithelial sodium channel activity in A6 cells via the peptide hormone, prolactin (1181.9)
Authors: Greenlee Megan , Mitzelfelt Jeremiah , Duke Billie Jeanne , Eaton Douglas 
Published: June 2021

Prolactin (PRL) is a peptide hormone well‐known for its role in lactation. PRL also has osmoregulatory actions via alteration of ion and water transport, actions characterized mostly in aquatic life. In 2003, researchers reported that PRL stimulates epithelial sodium channel (ENaC) activity in adult frog skin. Since that time, PRL‐mediated regulation of ENaC has been largely ignored. Given that ENaC present in the kidney plays an essential part in blood pressure control, we hypothesized that PRL may control blood volume and blood pressure via regulation of ENaC activity. To investigate this hypothesis, we used a well‐known frog kidney cell model (A6‐2F3) possessing amiloride‐sensitive transepithelial current and highly selective sodium channels with a conductance of ~5pS. Amiloride‐sensitive (ENaC‐mediated) current dramatically increased within 30 minutes after application of 1µg/mL PRL to the basal side of the cells ‐ an effect sustained even at 24 hours after treatment. We confirmed this finding using cell attached patch clamp. We found an almost 6 fold increase in ENaC NPo in PRL‐treated versus vehicle‐treated cells. The mechanism, although still not clear, at least partially involves JAK2 signaling since AG‐490, a JAK2 inhibitor, reduced the effect of PRL on amiloride‐sensitive current in A6 cells. Inhibitors of PI3K and SRC had no effect on PRL’s induction of amiloride‐sensitive current. In conclusion, we observed a significant induction of ENaC activity in frog kidney cells exposed to PRL ‐ an effect partially mediated through JAK signaling pathways. Future studies will finalize the signaling mechanisms involved in PRL’s activation of ENaC and the role of these pathways in blood pressure control.Grant Funding Source: Supported by NIH K12GM000680 and T32HL076118
Are the upper limits of cerebral autoregulation at gross and microcirculatory levels different? Does nitric oxide play a role? (1183.1)
Authors: Thompson Emma , Coney Andrew , Marshall Janice 
Published: June 2021

In Alfaxan‐anaesthetised, male Wistar rats, we infused phenylephrine (0.1‐200µg/kg/min i.v.) to raise arterial pressure (ABP). Dual‐line least‐squares analysis of gross cerebral blood flow (CBF), recorded from the common carotid with external carotid ligated, vs ABP, gave an autoregulatory upper limit (UL) of 168±3mmHg (n=14). By contrast, after neuronal NO synthase (nNOS) inhibition (ЅMTC; 0.56mg/kg i.v, or 7‐NI, 25mg/kg i.p. n=24), or non‐selective NOS inhibition (L‐NAME, 10mg/kg, n=9), the UL was either not reached, even when ABP reached 171±2 or 186±6* (vs Control; P<0.05) respectively or was increased to 173±2 (n=11) and 187±2mmHg* (n=4) respectively.When laser speckle imaging was used to follow tissue red cell flux (RCF) and diameters of arterial and venous vessels in the cerebral cortex, gross CBF UL was 168±5mmHg, but cortical tissue UL was higher; 170±5mmHg† (vs gross CBF UL, n=6). Further, in 4 rats after L‐NAME, the UL was not reached (either gross CBF or cortical tissue RCF) even when ABP was increased to 190±2mmHg*.We suggest that autoregulatory constriction of proximal cerebral arterial vessels when ABP rises is protective of cerebral tissue circulation, as indicated by the higher cortical tissue UL. We propose that NO synthesised mainly by nNOS induces tonic dilatation of cerebral circulation, such that its absence allows greater scope for autoregulatory vasoconstriction, leading to a raised UL.Grant Funding Source: Supported by the British Heart Foundation
The effects of transcranial Doppler probe placement on cerebral autoregulation measurements (1184.1)
Authors: de Jong Daan , Lagro Joep , Meel ‐ van den Abeelen Aisha , Slump Kees , Meulenbroek Olga , Claassen Jurgen 
Published: June 2021

Problem description: In measuring cerebral autoregulation (CA), transcranial Doppler (TCD) is currently the standard measurement technique for cerebral blood flow velocity (FV). However, this technique has a great operator dependency, affecting the reproducibility of the signals. This study assessed the effect of probe placement on TCD signal and on CA outcome measures.Methods: In 15 healthy young volunteers, blood pressure and FV were continuously measured. Changes in probe placement were applied systematically to assess the influence of probe position on absolute TCD measures (systolic, mean and diastolic FV), the pulsatility index (PI), and CA transfer function measures (gain, phase, and coherence).Results: Ranges of FV obtained after placement changes were 74‐133 % of the initially measured FV. With increases in measured FV , most subjects showed small decreases in the PI (up to ‐0.15 with p = 0.017). Transfer function analysis outcome measures varied, but did not show association with placement.Conclusion: This study indicates that the effects of placement of the TCD probes on CA measures are, if present, negligible. However, probe placement does have a strong influence on measured FV. This influence can be reduced by using a strict placement protocol, improving placement quality.
Evaluating the repeatability of measuring CBFV and estimating ARI at the MCA vs. ICA (1184.2)
Authors: Nogueira Ricardo , Saeed Nazia , Panerai Ronney , Robinson Thompson , Bor‐Seng‐Shu Edson 
Published: June 2021

Assessment of dynamic cerebral autoregulation (CA) at the internal carotid artery (ICA), as an alternative to blood flow velocity (BFV) measurements in the middle cerebral artery (MCA), has been recently demonstrated.This alternative is particularly important in cases where insonation of the MCA is not possible. However, the reliability and reproducibility of this approach using multiple operators have not been previously reported.Following confirmation of a plaque free carotid artery, BFV was measured at the ICA and MCA, synchronously with blood pressure, heart‐rate and end‐tidal‐CO2. The Autoregulation Index (ARI) was estimated using Tieck’s model. 11 healthy volunteers (10 female:, 48±11 years) were recruited. There were no significant differences in BFV MCA, BFV ICA or MCA ARI, ICA ARI between the left and right hemispheres or between operators. ARI estimates were not significantly different between MCA and ICA (operator 1: 6±2 and 5±2, operator 2: 5±2 and 5±2,respectively) or between operators within each location (MCA P=0.75, ICA P=0.98). Good reproducibility over repeated measurements between operators was evidenced by low coefficient of variation (%) between operators for BFV (MCA: 15%, ICA: 14%) and ARI (MCA: 24%, ICA: 27%). Therefore this study confirms that the ICA is a suitable location for CBFV and CA estimates, showing significant promise to evaluate the ICA ARI in patients where the temporal window is not available.