Increase In Discharge Frequency Research Articles

Efficient synthesis of CO and H2O2 via nanosecond pulsed CO2 bubble discharge

In the context of escalating global efforts to mitigate carbon emissions and explore sustainable energy resources, the transformation of CO2 into valuable chemicals and fuels via plasma technology has garnered significant attention. This study demonstrated a new pathway of CO2 conversion into CO and H2O2 via the bubble-enabled gas-liquid discharge driven by a nanosecond pulse. Results showed that the increased discharge frequency and larger pulse widths could enhance CO2 conversion rates and H2O2 yields, albeit potentially at the cost of reduced energy efficiency. Conversely, the rising time of pulse showed negligible impact on the process, whereas varying gas flow rates significantly altered CO and H2O2 yields, underscoring the nuanced influence of these parameters on the efficiency and selectivity of conversion processes. Through illuminating the dynamics of bubble discharge-assisted CO2 transformation, this study contributes to the broader understanding of gas-liquid discharge driven by nanosecond pulse, underlining its potential for addressing environmental and energy challenges.

Study on repeated discharge frequency characteristics of plasma pulse equipment

In order to increase the production of unconventional oil and gas, it is necessary to improve its reservoir. Plasma pulse technology is one of a safe and environmentally friendly reservoir reconstruction technology. In this paper, the discharge test of plasma pulse equipment was carried out in the laboratory. The different discharge stages (pre-discharge, main-discharge, sinusoidal attenuation oscillation and post-discharge stage) of plasma pulse equipment in a single discharge were discussed, and the frequency characteristics in the repeated discharge were studied in detail. The discharge test shows that the energy and average power of main-discharge stage are about 109 J and 15.6 MW respectively, and the discharge frequency range is about 0–25 Hz. Furthermore, the linear attenuation function model of breakdown voltage change under the initial discharge frequency of 4 Hz, 9 Hz, 14 Hz and 19 Hz is established, and the change law of breakdown voltage decreases linearly with the increase of discharge frequency is revealed. The results show that the research content of this paper has an important guiding significance for revealing the variation law of repeated discharge frequency characteristics of plasma pulse equipment, which is helpful to further optimize the design of plasma pulse equipment and improve its working performance.

Multifrequency Downstream Hydraulic Geometry of Alluvial Mountain Rivers Located on the Qinghai–Tibet Plateau

Downstream hydraulic geometry (DHG) for multiple discharge frequencies remains poorly investigated. This paper seeks to clarify the DHG relations of different discharge frequencies and proposes the definition, mathematical expression, and geomorphological interpretation of multifrequency DHG (MFDHG). It also verifies the existence of DHG and MFDHG in the six major exoreic rivers located in the Qinghai–Tibet Plateau. MFDHG can be depicted with (1) log-linear plots between DHG coefficients and exponents for multiple discharge frequencies and (2) independent DHG curves intersecting near congruent discharge, width, depth, or velocity. The results show that rivers in the study area exhibit strong DHG relations. The variations in the DHG coefficients and exponents usually exhibit opposite trends with increasing discharge frequency. The MFDHG of a river reach is generally stronger than that of a river basin. Congruent hydraulics, as indices of geometric variability and hydraulic self-similarity, reflect consistent changes in hydraulic variables downstream. MFDHG is a novel geomorphic phenomenon that bridges spatiotemporal dimensions in HG systems and provides a basis for establishing an overall HG relationship.

Effects of discharge characteristics and evaluation of pressure of shock wave on underwater discharge as pretreatment for enzymatic saccharification

Cellulosic bioethanol produced from wood is a candidate for alternative fuel to fossil fuels. In the cellulosic ethanol production process, pretreatment before enzymatic saccharification should be introduced for acceleration of the process. We proposed a new pretreatment technique for the cleavage of inter-cellulose hydrogen bonds by underwater discharge shock waves. In this study, we quantitatively analyzed the relationship among discharge conditions, shock wave properties, and treatment efficiency to estimate the optimal treatment conditions. The shock wave pressure was measured at several MPa, and optical microscopy results suggested wood flour fragmentation. The relationship between the discharge characteristics and the treatment effect was investigated by measuring the water retention value as an indicator of hydrogen bond cleavage and the amount of glucose as bioethanol intermediate products. The discharge energy of 0.85–1.16 J/pulse did not affect the treatment effect, while an increased discharge frequency in the range of 3.3–7.3 Hz did. The independence of treatment effect on the discharge energy was investigated to arise from the saturation in the discharge-current rising rate and shock-wave pressure.

Comprehensive optical diagnostics for flame behavior and soot emission response to a non-equilibrium plasma

This study reported comprehensive optical diagnostics for flame behavior and soot emission under directly coupling of the plasma with the flame at specific heights. The morphometric parameters of unstable flames under the direct plasma coupling were quantified. We also proposed an optical method to eliminate plasma luminescence from the field of view to extract flame intensity. At the same discharge height, with the increase of discharge frequency, the flame height decreased, while the flame horizontal extension distance and deflection angle increased. The relationships between flame morphologic and electrical parameters were obtained. The experimental results suggested a one-to-one correspondence between plasma action and flame deflection or shortening. When the plasma interacted with the flame, the overall temperature and soot emission of the flame decreased compared with that without plasma. At the same discharge height, the flame temperature and soot decreased further with the increase of discharge frequency. The soot emission changed more remarkably with the discharge frequency for higher discharge heights. With the increase of voltage, the flame temperature and soot increased at the lower discharge heights. The analysis of the experiment data demonstrated that the variation of soot emission was caused by the cooperation of multiple factors.

The effect of small changes in rate of force development on muscle fascicle velocity and motor unit discharge behaviour

When rate of force development is increased, neural drive increases. There is presently no accepted explanation for this effect. We propose and experimentally test the theory that a small increase in rate of force development increases medial gastrocnemius fascicle shortening velocity, reducing the muscle’s force-generating capacity, leading to active motor units being recruited at lower forces and with increased discharge frequencies. Participants produced plantar flexion torques at three different rates of force development (slow: 2% MVC/s, medium: 10% MVC/s, fast: 20% MVC/s). Ultrasound imaging showed that increased rate of force development was related to higher fascicle shortening velocity (0.4 ± 0.2 mm/s, 2.0 ± 0.9 mm/s, 4.1 ± 1.9 mm/s in slow, medium, fast, respectively). In separate experiments, medial gastrocnemius motor unit recruitment thresholds and discharge frequencies were measured using fine-wire electromyography (EMG), together with surface EMG. Recruitment thresholds were lower in the fast (12.8 ± 9.2% MVC) and medium (14.5 ± 9.9% MVC) conditions compared to the slow (18.2 ± 8.9% MVC) condition. The initial discharge frequency was lower in the slow (5.8 ± 3.1 Hz) than the fast (6.7 ± 1.4 Hz), but not than the medium (6.4 ± 2.4 Hz) condition. The surface EMG was greater in the fast (mean RMS: 0.029 ± 0.017 mV) compared to the slow condition (0.019 ± 0.013 mV). We propose that the increase in muscle fascicle shortening velocity reduces the force-generating capacity of the muscle, therefore requiring greater neural drive to generate the same forces.

Measurement of Wire Electrode Temperature in Wire Electrical Discharge Machining by Two-color Pyrometer with Optical Fiber

In wire electrical discharge machining (EDM), increase of the wire temperature influences the wire breakage during machining because the increase of the temperature leads to the decrease in mechanical strength of the wire electrode. In this study, in order to measure the wire temperature during wire EDM, a two-color pyrometer with an optical fiber was used. Experimental results showed that the infrared light radiated from the wire electrode during machining could be detected by the two-color pyrometer, and the temperature of wire electrode could be measured. The output ratio increased with the increase of discharge frequency, which means that the temperature of the wire electrode increased with increasing the discharge frequency.

Degradation of toluene by tube-tube coaxial dielectric barrier discharge: power characteristics and power factor optimization

ABSTRACT In this paper, the power characteristics and power factor optimization were investigated in a coaxial tube–tube dielectric barrier discharge (DBD) reactor. The effects of several parameters, including discharge voltage, discharge length, discharge frequency and gas flow rate on discharge power and power factor have been evaluated. The experiment results showed that higher discharge power can be obtained by increasing the discharge voltage, discharge frequency and electrode length. But for the power factor, with the increase of discharge frequency, the power factor increased firstly and then decreased. Moreover, with the discharge length increased, the discharge frequency when the power factor reached the maximum value reduced. The response surface method (RSM) and artificial neural network (ANN) were used to optimize the power factor, and their results were relatively consistent. The result of the ANN showed that when discharge voltage was 9.58 kV, discharge frequency was 8.69 kHz, discharge length was 15.8 cm, and gas flow rate was 1.5 L/min, the power factor reached the maximum value of 0.362. The degradation experiment of toluene was carried out in the reactor and its degradation effect was analyzed. The toluene degradation rate is positively correlated with the power factor, and the discharge voltage, gas flow rate and initial concentration are also the key parameters to determine the degradation of toluene. When the discharge voltage, gas flow rate, and initial concentration are 10 kV, 70 mL/min, and 50 ppm, respectively, the power factor and toluene degradation rate reach 0.34 and 74.3%.

Enhanced transmembrane transport of reactive oxygen species by electroporation effect of plasma

AbstractRecently, plasma has been proposed as a new efficient tool for various biological and medical applications. The function of plasma is mainly realized through two aspects: Electric field and reactive species. However, because the interactions between plasma and cells are quite complicated, the synergistic effect of electric field and reactive species has not been studied in depth. In this paper, the synergetic effects of electric field and transportation of reactive species on cells are investigated by a two‐dimensional finite element model. The exposure of cells to plasma results in the sufficiently high transmembrane voltage (1 V) and electroporation. When the electric field of plasma is less than 104 V/cm, the radius of nanopores generated by plasma increases with the electric field. The further increase of electric field to 105 V/cm does not cause a significant increase of nanopore radius, whereas the pore density increases by five times. The increase of discharge frequency significantly decreases the time needed to generate stable nanopores. The nanopores enhance the diffusion of H2O2 generated by plasma through the cell membrane significantly. Compared with the reality that H2O2 does not freely diffuse across cell membranes, the “generation and enhanced transportation” effect will further expand the application range of plasma medicine.

Hydrogen production by the steam reforming and partial oxidation of methane under the dielectric barrierdischarge

The steam reforming and partial oxidation of methane to produce hydrogen under dielectric barrier discharge were conducted in the CH4-O2-N2-H2O reaction system; the effects of H2O/CH4 molar ratio, O2/N2 molar ratio, total gas flow, discharge voltage and discharge frequency on the hydrogen production were investigated and the reaction mechanism was analyzed on the basis of the in-situ diagnostic emission spectroscopy. The results indicate that the conversion of methane and the yield of hydrogenincrease with the increase of H2O/CH4 molar ratio, O2/N2 molar ratio, and discharge voltage, but decrease with the increase of the total gas flow rate and show a volcano-shape trend with the increase of discharge frequency (peaked at 9.8 kHz). Under the conditions with an H2O/CH4 molar ratio of 1.82, O2/N2 molar ratio of 2.1, total flow rate of 136 mL/min, discharge voltage of 18.6 kV and discharge frequency of 9.8 kHz, in particular, the conversion of methane and the yield of hydrogen reach 47.45% and 21.33%, respectively. During the reaction, methane and water vapor may dissociate by the action of high energy electrons to generate CHx·, H·, OH·, O· and other free radicals and hydrogen is then produced through the collision between the free radicals. H· may come from the electronic dissociation of CH4 as well as the dissociation of OH· formed primarily from the water vapor dissociation. The partial oxidation of methane is mainly manifested by the oxidation of CH2· with O·, where O· is produced by the electronic dissociation of O2 as well as the further dissociation of OH·

A review on various methods to improve process capabilities of electrical discharge machining process

The propensity to increase the machining performance of various electric discharge machining (EDM) processes is becoming more and more prominent by many researchers. The exploitation of vibration to the workpiece, tool, and dielectric fluid in various mediums like fluid and gas, the addition of additives to dielectric medium examined by the researchers. The results of the research show a significant improvement in the process in terms of enriched material removal rate (MRR), reduced tool wear, and quality finish. This research article reviews the application of vibration to the electrodes, dielectric medium, and the use of different additives in a dielectric medium in various EDM processes. The review of various vibration-assisted techniques, powder mixed EDM, and their impact on output performance parameters have been described. Literature suggested that the exploitation of vibration to the electrodes enhanced the output process parameters in terms of higher MRR, minimum tool wear, and superior surface quality due to optimum flushing performance of contaminants from the gap. The application of vibration also reduced the short-circuiting, increased discharge frequency, and stabilizes the machining process. The literature on adding additives in various EDM processes also reported a significant improvement in the machining performance by reduced short-circuiting thereby reducing insulating characteristics of the dielectric medium. Based on the review the research opportunities for researchers for further research have been identified to strengthen the capabilities and capacity of various EDM processes.

Wnt5b/Ryk-mediated membrane trafficking of P2X3 receptors contributes to bone cancer pain

Wnt5b, a member of Wnt family, plays multiple roles in tumor progression and metastasis. However, whether Wnt5b contributes to the sensitization of dorsal root ganglia (DRG) neurons and pathogenesis of bone cancer pain still remains unclear. Here, we found that the protein expression of Wnt5b and its atypical tyrosine protein kinase receptor Ryk was upregulated in ipsilateral DRGs in tumor-bearing mice. Application of Wnt5b evoked an increased discharge frequency in isolated DRG neurons and pain hypersensitivity in naïve mice which were almost completely prevented by anti-Ryk antibody. Moreover, intrathecal injection of anti-Ryk antibody to tumor-bearing mice significantly inhibited bone cancer-induced mechanic allodynia and thermal hyperalgesia. Subsequently, we also demonstrated that application of Wnt5b to cultured DRG neurons could enhance membrane P2X3 receptors and α,β-meATP-induced currents. Intrathecal injection of calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93 or P2X3 receptors antagonist A317491 almost completely abolished Wnt5b-induced mechanical allodynia and thermal hyperalgesia in mice. Meanwhile, pretreatment with anti-Ryk antibody or CaMKII inhibitor KN93 can attenuate bone-cancer induced the upregulation of P2X3 membrane protein as well as pain hypersensitivity. These findings suggested that Wnt5b/Ryk promoted the trafficking of P2X3 receptors to the membrane via the activation of CaMKII in primary sensory neurons, resulting in peripheral sensitization and bone cancer-induced pain. Our results may offer a potential therapeutic strategy for bone cancer pain.

Neural pathway between the nucleus accumbens and the rostral ventrolateral medulla in a rat model of anorexia nervosa

To investigate the potential neural pathway connecting the nucleus accumbens (NAc) and the rostral ventrolateral medulla (RVLM), and whether the pathway participates in the regulation of cardiovascular function in a model rat of anorexia nervosa (AN). Rat models of AN were established by allowing voluntary activity in a running wheel with restricted feeding, with the rats having free access to normal chow without exercise as the control group. FluoroGold (FG) retrograde tracing method and multi-channel simultaneous recording technique were used to explore the possible pathway between the NAc and the RVLM. The rats in AN group exhibited significantly reduced systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) with significantly increased discharge frequency of RVLM neurons in comparison with the control rats. After the injection of FG into the RVLM, retrograde labeled neurons were observed in the NAc of the rats in both the normal control and AN groups. In both groups, SBP and HR were significantly decreased in response to 400 μA electrical stimulation of the NAc accompanied by an obvious increase in the discharge frequency of the RVLM neurons; the diastolic blood pressure (DBP) and MAP were significantly lower in AN model rats than in the normal rats in response to the stimulation. We successfully established a rat model of AN via hyperactivity and restricted feeding and confirm the presence of a neural pathway connecting the NAc and the RVLM. This pathway might participate in the regulation of cardiovascular function in AN model rats.

Excitatory and aversive behaviors - electrophysiological observation of anterior cingulate cortex (ACC) in rats

Increasing activities in anterior cingulate cortex (ACC) can enhance the aversion reactions associated with noxious stimuli. It has been known that opioid receptors activation can trigger endogenous analgesic effect. This study tried to explore whether opioid receptors activation in the ACC region could reduce the aversion associated with noxious stimuli. The experimental rats were randomly divided into seven groups, Complete Freund's adjuvant (CFA) + normal saline (NS) group, normal saline (NS) + normal saline (NS) group, normal saline (NS) +DAMGO ((DAla2, NMe-Phe4, Gly-ol5)enkephinlin, μ-opioid receptor agonist) group, complete Freund's adjuvant (CFA)+ 0.01/0.04/0.2/1 μg/μl DAMGO group(n=6). The experimental period was three days. The basal value was measured on the first day. The second day, 1 μl was administered through the ACC area, and then 0.08 ml of complete Freund's adjuvant (CFA) was injected into the left hind paw of the rat. CPA response, paw withdrawal reflex latency (PWL) and electrical activity in the ACC brain region of rats were observed on the third day. ①PWL was significantly decreased in rats after CFA was injected into left hind paw compared with post-injection(P＜0.05).② In the pain side of the apparatus, it took rats less residence time than that in the non-pain side. ③ 0.04/0.2/1 μg/μl DAMGO was given before CFA-injection, C-CPA reactions could be revised significantly. ④ Given 0.04/0.2/1 μg/μl DAMGO in the ACC region could decrease the increasing discharge frequency induced by CFA in ACC neurons. The activation of the mu-opioid receptor in the ACC region alleviates the aversion induced by noxious stimulation.

Direct observation of discharging phenomena in vibration-assisted micro-electrical discharge machining

It has been previously reported that electrical discharge machining (EDM) performance can be improved by tool electrode vibration. However, the mechanism of vibration-assisted EDM has not been clarified and the optimal vibration condition remains unknown due to the difficulty in direct process observation. In this study, direct observation of the EDM gap by using a high-speed video camera through a transparent workpiece electrode made of single-crystal 4H-SiC was attempted. It was found that tool vibration caused discharge dispersion and discharge frequency increase, and this tendency was more significant at higher amplitudes and higher frequencies. In addition, tool vibration-induced periodic discharge was observed, which prevented concentrated discharge and short-circuiting. Accordingly, the machining speed was improved and surface roughness was reduced. This study succeeded for the first time in observing the discharge behaviors in vibration-assisted EDM, thus revealed the effects of key parameters for process optimization.

Effects of discharge parameters on carbon dioxide conversion in TiO2 packed dielectric barrier discharge at atmospheric pressure

A cylindrical dielectric barrier discharge reactor packed with TiO2 is developed to convert undiluted carbon dioxide (CO2) into CO and O2 at atmospheric pressure. Basing on linear regulation of instruments, a series of typical discharge parameters have been electrically controlled and measured in an attempt to find the maximum CO2 conversion and the best energy coupling. It is discovered that CO2 conversion has a stronger correlation with apply voltage, and further research manifested that lowering feed gas flow and increasing discharge frequency contribute to higher CO2 conversion within our controllable range. After comprehensive analysis of these trends and results of subsequent experiments, the maximum CO2 conversion of 12.72% is achieved at the voltage of 22 kV, with 9.09 kHz frequency and 20 ml/min flow rate, and the highest energy efficiency of 15.80% is achieved at the voltage of 22 kV, with 8.47 kHz frequency and 20 ml/min flow rate.

Experimental investigation of hydrogen production by CH4–CO2 reforming using rotating gliding arc discharge plasma

Hydrogen produced from CH4–CO2 reforming by an optimized rotating gliding arc discharge plasma reactor is investigated in this study. The effect of CH4/CO2 ratio (mole ratio), total input flow rate, discharge gap, voltage, and discharge frequency are analyzed. The results show that H2 yield increases with the increase of CH4/CO2 ratio. Arc can be stretched effectively by increasing total input flow rate, then the discharge region is enlarged. Increasing discharge gap can enlarge the discharge region, but the reaction of the gas mixture would be suppressed if the discharge region was excessively large. The discharge region decreases with the increased discharge frequency to a certain degree. Based on the experimental results, the optimal experimental condition is concluded as applied voltage 60 V, discharge frequency 20 kHz, and minimum discharge gap 3 mm. It is anticipated that the results would serve as a good guideline to the application of hydrogen production from hydrocarbon fuels by plasma reforming onboard.

Abstract 107: Neurons in the Organum Vasculosum of the Lamina Terminalis Sense NaCl and Angiotensin II to Regulate Sympathetic Nerve Activity and Arterial Blood Pressure

The organum vasculosum of the lamina terminalis (OVLT) contains specialized neurons that sense changes in extracellular NaCl concentrations to regulate sympathetic nerve activity (SNA) and arterial blood pressure (ABP). However, OVLT neurons also abundantly express angiotensin II (AngII)-type I receptors. Therefore, we performed a series of in vitro and in vivo studies in adult male Sprague-Dawley rats to determine whether OVLT neurons sense both NaCl and AngII to impact SNA and ABP. First, in vitro whole-cell recordings revealed the majority of OVLT neurons (66%, 23/35) showed an increased discharge frequency to both +7.5mM NaCl (1.1±0.2 to 2.2±0.3Hz, P<0.001) and 100pM AngII (1.3±0.3 to 2.2±0.3Hz, P<0.001). Second, in vivo single-unit recordings demonstrate the majority of OVLT neurons (61%, 11/18) displayed an increase in cell discharge to intracarotid injection of 0.5M NaCl (3.6±0.6 to 9.0±1.6Hz, P<0.01) and 200ng AngII (3.2±0.7 to 9.2±1.9Hz, P<0.01). Third, optogenetic inhibition of OVLT neurons (rAAV2-CaMKII-eNpHR3.0-mCherry, 5x10 12 particles/mL, 561nm, 10mW) attenuated thirst responses to IV infusion of 2M NaCl (1.25mL/30min; Laser OFF: 6.1±0.5mL vs ON: 2.0±0.7mL, P<0.05) and AngII (Laser OFF 7.2±0.7mL vs ON: 2.2±1.2mL; n=5 per group, P<0.05). Fourth, OVLT injection (20nL) of 0.5M NaCl or 10pmol AngII increased SNA (121±6% or 117±5%, n=4/group; P<0.05 respectively) and mean ABP (7±1 or 9±2mmHg, n=4/group; P<0.05 respectively). To determine whether chronic activation of OVLT neurons produces hypertension, rats received an OVLT injection of rAAV2-hSyn-HM3D(Gq)-mCherry (3x10 12 particles/mL, 50nL) and given access to 0.1% NaCl chow and 0.9% NaCl drinking solution. After 4 weeks, daily administration of clozapine-N-oxide to the drinking solution (3mg/kg/day) significantly increased 24-h fluid intake (baseline: 60±10mL vs Day 7: 178±29mL; n=6, P<0.01) and 24-h mean ABP (baseline: 97±2mmHg vs Day 7: 108±1 mmHg; n=6, P<0.05). Ganglionic blockade with hexamethonium (30mg/kg, ip) produced a greater fall in mean ABP at Day 7 (baseline: -38±6 mmHg vs Day 7: -53±5 mmHg, P<0.05). These findings suggest OVLT neurons sense both NaCl and AngII to regulate body fluid homeostasis and SNA to produce a sympathetically-mediated hypertension.

Neurons in the Organum Vasculosum of the Lamina Terminalis Sense Both Angiotensin II and NaCl to Regulate Thirst

Angiotensin II (AngII) and NaCl are sensed by hypothalamic circumventricular organs to subsequently regulate body fluid homeostasis and blood pressure. AngII predominantly acts within the subfornical organ (SFO), whereas NaCl is sensed by neurons in the organum vasculosum of the lamina terminalis (OVLT). However, OVLT neurons also abundantly express AngII‐type I receptors. Therefore, we performed a series of in vitro and in vivo experiments in adult male Sprague‐Dawley rats to determine whether OVLT neurons sense both AngII and NaCl to impact body fluid homeostasis. First, in vitro whole‐cell recordings were performed on OVLT neurons in the presence of kynurenic acid (1mM) and bicuculline (20μM) to assess discharge responses to +7.5 mM NaCl (3 min) versus 100pM AngII (90s) in a randomized order. The majority of OVLT neurons (66%, 23/35) demonstrated an increase in discharge frequency to both AngII (1.31±0.25Hz to 2.19±0.31Hz; p<0.001) and hypertonic NaCl (1.11±0.18Hz to 2.16±0.27 Hz; p<0.001). Smaller proportions of OVLT neurons were either excited by NaCl alone (3/35), AngII alone (4/35), neither stimulus (3/35), or were inhibited by NaCl (2/35). In a second set of experiments, in vivo single‐unit recordings of OVLT neurons were performed to assess discharge responses to intracarotid injection (50uL over 15 s) of hypertonic NaCl (0.5M NaCl) or AngII (200ng). Half of OVLT neurons (50%, 6/12) displayed an increase in discharge to intracarotid injection of AngII (3.2±0.7 to 9.2±1.9 Hz, P<0.01) and 0.5M NaCl (3.6±0.6 to 9.0±1.6 Hz, P<0.01). The remainder of OVLT neurons showed an increase in discharge to hypertonic NaCl only (n=1) or AngII only (5/12). In a final set of experiments, we employed an optogenetic approach to determine the extent by which inhibition of OVLT neurons would attenuate thirst stimulated by NaCl versus AngII. rAAV2‐CamKII‐eNPHR3.0‐mCherry (5×1012 particles/mL, 50nL) was injected into the OVLT, and an optical ferrule (200um OD) was implanted 300um dorsal to the injection site. Approximately 4 weeks later, optogenetic inhibition of OVLT neurons (561nm, 10mW) significantly reduced water intake in response to intravenous infusion (1.25 mL per 30 min) of 2M NaCl (control: 5.1±0.9 mL vs laser: 1.6±0.9 mL; n=4, P<0.01). In addition, optogenetic inhibition of OVLT neurons also attenuated hypotension‐induced thirst produced by intravenous injection of 25 mg/kg diazoxide (control: 4.5±0.8 mL vs laser: 1.3±0.7 mL; n=4, P<0.01). These findings suggest that individual OVLT neurons can sense both NaCl and AngII to functionally regulate thirst to both stimuli.Support or Funding InformationNIH R01 HL113270 and AHA Established Investigator AwardThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The protective effects of electro-acupuncture in thoracic surgery on trauma stressed rats involve the rostral ventrolateral medulla and supraoptic nucleus.

The present study was designed to explore whether the rostral ventrolateral medulla (RVLM) and supraoptic nucleus (SON) were involved in the protective effects of electro-acupuncture (EA) in thoracic surgery on trauma-stressed rats. The rats were randomly divided into a non-stressed group (Control), surgical trauma-stressed group (Trauma), and Neiguan EA applied on the surgical trauma-stressed group (Trauma+EA-PC 6). RVLM neuron discharge was observed by using an in vivo electrophysiological method, and micro-dialysis combining high-performance liquid chromatography with fluorometric detection (HPLC-FD) was used to assess expression of amino acids in the RVLM. Immunohistochemical methods were used to assess c-Fos expression in SON neurons. The trauma of surgical stress was shown to dramatically increase the discharge frequency of RVLM neurons and promote the release of glutamate and taurine in the RVLM. The expression of c-Fos was also significantly increased in the SON of traumatized rats. EA application at Neiguan acupoints significantly suppressed trauma-induced increase of discharge frequency of the RVLM neurons, almost completely suppressed the trauma-induced increase of glutamate release but only very slightly reduced the trauma-enhanced taurine release, and inhibited the increase of c-Fos expression in these SON neurons of traumatized rats. These results indicate that Neiguan EA may improve cardiac function by modulating neurons in the RVLM and the SON in surgically traumatized rats. The taurine-mediated negative feedback may be involved in the protective effect of EA on cardiac function.