bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exercise Training Improves the Arterial Baroreflex Function in Hypertensive Rats
Authors: Pan Yan‐Xia , Hong Lin , Zhao Xiao‐Lin , Lin Cheng 
Published: November 2023

ObjectiveTo investigate the influence of exercise training on the arterial baroreflex and its central mechanisms in spontaneously hypertensive rats (SHR).MethodsTwenty male SHR and 24 normotensive Wistar rats were randomly assigned into control group (C) or exercise training (E) group. All experimental procedures were in conformance with the FASEB Statement of Principles for the use of animals in research and education. Exercise training was performed on a treadmill for 8 weeks. Systolic blood pressure and heart rate were measured by tail‐cuff method. Baroreflex sensitivity(BRS) was determined by intravenous injection of phenylephrine (PE) and sodium nitroprusside (SNP). Alterations in the BRS were evaluated before and after intracerebroventricular administration of superoxide dismutase (SOD) mimetic Tempol or SOD inhibitor DETC. Malondialdehyde (MDA) content, total antioxidant capacity (T‐AOC), superoxide dismutase (SOD) and catalase (CAT) antioxidant enzyme activities in the hypothalamus were measured to assess oxidative state.ResultsBefore exercise training, systolic blood pressure in two groups of SHR was obviously higher than those in normotensive Wistar rats (P<0.01). Exercise training significantly decreased heart rate in SHR and Wistar rats and systolic blood pressure in SHR alone. The BRS of control SHR was significantly lower than that of normotensive Wistar rats [PE: (0.89 ± 0.22) vs. (1.96 ± 0.23) bpm/mmHg, P <0.001; SNP: (0.62 ± 0.10 ) vs. (1.32 ± 0.23) bpm/mmHg, P<0.001). Exercise training significantly improved the BRS of SHR. Compared with control SHR, the BRS of the trained SHR was significantly increased [PE: (1.31 ± 0.26 ) vs. (0.89±0.22) bpm/mmHg, P <0.001 SNP: (1.22 ± 0.25) vs. (0.62±0.10)bpm/mm Hg, P <0.01). Intracerebroventricular infusion of DETC abolished the beneficial effect of exercise training on the BRS in SHR rats (P<0.05) and significantly decreased the BRS in two Wistar groups (P < 0.05). In contrast, Tempol greatly improved the BRS in two SHR groups (P<0.05) and normalized the BRS of the trained SHR. Exercise training decreased MDA content in the hypothalamus of SHR by 27% (P<0.05), but increased T‐AOC, SOD and CAT activities by 74%, 41% and 62%, respectively (P<0.05). In addition, exercise training decreased MDA content in the hypothalamus of Wistar by 40% (P<0.05), but increased T‐AOC, SOD and CAT activities by 72%, 30% and 51%, respectively (P<0.05).ConclusionsCentral oxidative stress depresses the arterial baroreflex, and exercise training –induced reduction of central oxidative stress contributes to improved arterial baroreflex function in SHR by the enhancement of antioxidant enzyme activity and antioxidant capacity in the brain.Support or Funding Informationthe National Natural Science Foundation of China (No.81372111)the Natural Science Foundation of Fujian Province (No. J01339)
Effect of electroacupuncture on cardiac excitability during sympathoexcitation induced by acute ischemia and left stellate ganglion stimulation in a porcine model
Authors: Zhou Wei , Takamiya Tatsuo , Yamamoto Kento , Mahajan Aman 
Published: November 2023

Augmentation of cardiac sympathetic tone during myocardial ischemia has been shown to increase myocardial O2 demand and infarct size as well as induce arrhythmias. We have previously demonstrated that electroacupuncture (EA) mitigates myocardial ischemia‐reperfusion injury by modulation of cardiac norepinephrine release. The purpose of this study is to determine the effects of EA on cardiac excitability evaluated by measurement of activation recovery interval (ARI) and heart rate variability (HRV) by using power spectral analysis. A median sternotomy was performed to expose the heart and the left stellate ganglion (LSG). Acute myocardial ischemia (AMI) was induced by ligation of left descending coronary artery. A 56‐electrode was placed on the heart to record ARI, a surrogate measure of action potential duration. AMI with LSG stimulation significantly shortened ARI by 5.4% and increased dispersion by 160% as well as increased LF/HF from 0.31 to 1.18 (n.u.). 30 min of EA significantly attenuated the ARI shortening (1.7% vs. 5.4%) and dispersion (104% vs. 160%) as well as decreased the LF/HF from 1.18 to 0.70 (n.u.) with decreased LF components from 46.5±3.5 to 27.2±4.1(n.u.) and increased HF components from 38.5 to 49.2 (n.u.). In conclusion, EA modulates the cardiac excitability through inhibition of sympathetic nerve system and activation of parasympathetic nerve system.Support or Funding InformationDepartment Fund
The Correlation between Heart Rate Variability and Diet
Authors: Murray Olivia , Vick Robert 
Published: November 2023

Heart function can be affected by lifestyle choices. Heart rate variability (HRV) is the variation in the time interval between heartbeats and can be used as a means to assess cardiac health (Stein & Kleiger 1999). A high HRV is indicative of good cardiac health and increased parasympathetic activity, while a low HRV has been associated with poor outcomes in adults (Kristal‐Boneh et al. 1995). This study investigated the correlation between overall diet and HRV. Thirty‐two participants aged 18–22 years old were recruited based on their diet. Diets represented in this study included vegetarian, dairy‐free, and gluten‐free, as well as participants that had no dietary restrictions, to act as controls. A 5‐minute electrocardiogram (ECG) was performed on each participant. Software supplied by ADInstruments was used to generate a spectral analysis of HRV by applying a Fast Fourier Transformation (FFT). Frequencies were subdivided as Very Low Frequency (VLF) and Low Frequency (LF), which correlates to a combination of sympathetic and parasympathetic effects, and High Frequency (HF), which correlates to parasympathetic effects. Time domain and frequency domain measures of HRV were analyzed through SPSS Statistics software. No significant differences between the diet groups were found; however, there were differences in the standard deviation of all normal RR intervals (SDRR) of each group (vegetarian = 104.66 ms, gluten‐free = 81.5 ms, healthy = 66.34 ms, unhealthy = 59.13 ms, and control = 87.07 ms). A moderate negative correlation was found between consumption of fast food and frequency HRV measures (HF power: r = −.397, p = .024), indicating that with increasing fast food consumption, there is an increasing risk for an adverse cardiac outcome. In general, diet does seem to result in small differences in HRV, especially between the unhealthy diet group, which is characterized by high consumption of red meat, fast food, alcohol, and sweets, and the vegetarian diet group, specifically for the LF domain (p=0.17). Additionally, after sorting the data through time domains rather than FFT, it was found that the vegetarian group had a SDRR greater than 100 ms, correlating with a low risk of cardiac problems as determined by previous parameters (Torres et al. 2008).Support or Funding InformationFunding was obtained through the Elon University Undergraduate Research Program and the Elon College Fellows Program.
Leptin Facilitates Phrenic and Abdominal Nerve Activity During Chemoreflex Activation
Authors: Bassi Mirian , Furuya Werner Issau , Zoccal Daniel Breseghello , Menani José Vanderlei , de Almeida Colombari Débora Simões , Colombari Eduardo 
Published: November 2023

Leptin acts in the central nervous system (CNS) enhancing chemorespiratory responses by mechanisms not yet completely understood. In the present study, we evaluated the pulmonary ventilation and the activity of the phrenic and abdominal nerves during activation of chemoreflex in rats treated chronically with leptin. Juvenile Holtzman rats (22–28 day old) received leptin (40 mg/day/7 days) or saline infusion subcutaneously. On the 6th day of infusion, pulmonary ventilation was recorded by whole body plethysmography and on the seventh day, nerve activity was recorded in the in situ heart‐brainstem preparation. The chemoreflex response was activated by KCN (0.04%) or hypercapnia (10% CO2). In both preparations, ventilation or nerve activities were recorded before and during chemoreflex activation. Leptin reduced the gain of body weight (30 ± 9 g vs. saline: 49 ± 2 g, p <0.05). Ventilation increased more during hypercapnia in rats treated with leptin infusion (1284 ± 109 ml.kg−1.min−1, vs. saline: 967 ± 66 ml.kg−1.min−1, p <0.05). In the in situ preparation, the increased activity of the phrenic and abdominal nerve produced by the activation of chemoreflex with KCN was strongly potentiated by leptin (45% ± 9 and 263 ± 83% vs. saline: 17 ± 3% and 93 ± 45% respectively, p <0.05). Similar increased responses were observed during hypercapnia in the in situ preparation. The results suggest that leptin enhances the chemoreflex response increasing inspiratory and expiratory activities.Support or Funding InformationFAPESP; CNPQ; AND PNPD‐CAPES.
Renal Afferent Peptidergic Neurons – What are Primary Stimuli ?
Authors: Ditting Tilmann , Rodinova Kristina , Loosen Sonja , Hilgers Karl , Ott Christian , Schmieder Roland E , Amann Kerstin , Veelken Roland 
Published: November 2023

Renal afferent nerve fibers comprise a complicated neuro‐paracrine regulatory system significantly influencing the sympathetic nervous system in health and disease, We wanted to test the hypothesis that the activity of renal afferent neuronal units is primarily altered by inflammatory processes in cardiovascular disease.As inflammatory model, normotensive renal inflammation (Thy‐1) was induced by i.v. injection of 1.75 mg/kg BW Thy‐1 antibody to rats, hypertension by unilateral clipping of one renal artery (2K1Cl model) in rats 3 weeks prior to experiments. Controls were sham‐treated, respectively. Retrograde labelling (DiI) allowed the identification of renal afferent neurons situated in the dorsal root ganglion (DRG) (Th11‐L2). Patch clamp recordings, i.e. current clamp allowed to characterize neurons as highly active or “tonic”, i.e. sustained action potential (AP) firing versus low active or “phasic”, i.e. <5 APs according to their firing response to current injections. Electrophysiological parameters and AP properties were determined in all experimental groups and controls, proteinuria and renal morphology assessed for all kidneys.In nephritic rats, the number of neurons with a tonic, more active response pattern decreased significantly (43,4% vs. 64,8%, p<0.05) as compared to controls. Interestingly. in renovascular hypertension (2K1Cl model, n=92) only neurons with projections to the clipped kidney showed a significant decrease in tonic firing pattern (30.6% [23/75]), whereas the non‐clipped kidney showed an unaffected proportion of tonically firing neurons (67.5% [50/74], p<0.05) as compared to controls. There was no increase in blood pressure (BP) in Thy‐1 animals, hence confounding effects of BP were unlikely. RI rats exhibited albuminuria (61±6 μg/24h), infiltration of macrophages in the interstitium (26 ± 4 cells/high‐power field) and glomeruli (3.7±0.6 cells/glomerular cross‐section) as signs of active renal inflammation. In contrast, in 2K1Cl animals BP was increased to 180/100 mmHg, but no signs of renal inflammation could be detected as in Thy‐1 rats.In contrast to our hypothesis inflammation per se (and especially hypertension) may play less important roles for the decreased activity pattern of afferent renal neuron as seen in our experiments. Rather altered perfusion occurring in a clipped kidney with renal stenosis and likely also present in nephritis might be of pivotal importance.Support or Funding InformationDeutsche Forschungsgemeinschaft
Cardiovascular Autonomic Tone in Rats with Heart Failure Treated with Allogeneic Mesenchymal Stem Cells
Authors: Morais Sharon DBV , Lataro Renata Maria , Silva Carlos Alberto Aguiar , Meirelles Lindolfo S , Fazan Rubens , Salgado Helio Cesar 
Published: November 2023

Autonomic imbalance with lower cardiac vagal tone and sympathetic overactivity is a trademark of heart failure (HF) in either patients or experimental models of this disease. We evaluated the effect of bone marrow mesenchymal stem cells (MSC) on cardiovascular autonomic function in rats with chronic HF, induced by myocardial infarction (MI). Male Wistar rats were subjected to surgical ligation of left coronary artery to induce MI. After 7 days they were intravenously treated with MSC (106cels/250μL, N=11), or vahicle (saline, N=13). Control (non‐infarcted, N=14) rats were also evaluated. Five weeks after MI rats were implanted with subcutaneous electrodes for electrocardiogram (ECG). After 48 h, conscious freely moving rats underwent to basal ECG recording for 60 min hereafter received intravenous injection of methyl‐atropine followed by propranolol (or vice versa) to evaluate cardiac autonomic tone. Changes in heart rate (HR) elicited by methyl‐atropine and propranolol were considered as cardiac vagal and sympathetic tones, respectively. HR interval was similar among groups (313±6, 312±6 and 300±6 bpm). Surprisingly cardiac sympathetic tone was similar among groups (9±3, 14±3 and 11±4 bpm). On the other hand, cardiac vagal tone was significantly lower in saline‐treated infarcted rats (53±7 bpm) as compared to non‐infarcted control counterparts (84±7 bpm). MSC‐treated infarcted animals showed same vagal tone as control rats (97±10 bpm). Moreover, intrinsic HR, i.e. HR after double autonomic receptors blockade, was lower in non‐treated (saline) infarcted rats (344±5 bpm) as compared to control and to MSC‐treated infarcted rats (365±5 and 371±7 bpm). In conclusion, our data demonstrate that MSC therapy was effective to improve cholinergic autonomic tone of the heart and intrinsic HR.Support or Funding InformationFAPESP, CNPq, FAEPA
Obstructive sleep apnea impairs insulin resistance in metabolic syndrome patients with normal levels of glucose
Authors: Cepeda Felipe Xerez , Rodrigues Sara , Dutra‐Marques Akothirene CB , Carvalho Jefferson Cabral , Toschi‐Dias Edgar , Jordão Camila Paixão , Rondon Maria Urbana , Alves Maria Janieire N.N. , Lorenzi‐Filho Geraldo , Trombetta Ivani Credidio 
Published: November 2023

Intermittent hypoxia, a hallmark of obstructive sleep apnea (OSA), impairs glucose metabolism. Systemic inflammation is one mechanism involved in this impairment. Since OSA is highly prevalent in metabolic syndrome patients (MetS), we tested the hypotheses that: 1) Even with normal glucose levels, the presence of OSA in MetS worsens insulin sensitivity (IS); 2) The minimal oxygen saturation (Minimum SaO2) during polysomnography is associated with inflammation; and 3) The inflammation is associated with (IS). Thirty one newly diagnosed MetS (ATP III) with fasting glucose <100mg/dL were divided into: MetS+OSA (n=12, 46±3y) and MetS‐OSA (n=19, 42±2y), and compared with healthy control (C, n=11, 49±2y). OSA was characterized by apnea‐hypopnea index (AHI) >15 events/h. The pro‐inflammatory marker C‐reactive protein (CRP) was examined. We evaluated the IS by HOMA‐IR. All groups were similar in glucose levels. Both MetS groups were similar in MetS risk factors and different than C. MetS+OSA had similar to MetS‐OSA, but is higher than C for HOMA‐IR (4.1±0.5 vs. 3.0±0.4 and C, 2.0±0.2, respectively, P<0.01). Interestingly, in the MetS+OSA we found an association with Minimum SaO2 with PCR (R=−0.71; P<0.001). Moreover, the PCR was associated with HOMA‐IR (R=−0.62; P<0.001). In conclusion, our data suggest that the overlap of OSA in patients with MetS with normal levels of glucose impairs IS which may be explained, at least in part, inflammation as a response for the chronic intermittent hypoxia oxygen desaturation during sleepSupport or Funding InformationThis study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP# 2011/17533‐6 ) and, in part, by Fundação Zerbini.Felipe X Cepeda was supported by FAPESP# 2015/03274‐0,Sara Rodrigues was supported by FAPESP# 2013/15323‐0,Edgar Toschi‐Dias was supported by FAPESP# 2013/07651‐7.
Contrasting Effects of Acute Versus Chronic Intermittent Hypoxia on Leptin Secretion in Differentiated Human Preadipocytes
Authors: Somers Kiran R , Becari Christiane , Polonis Katarzyna , Singh Prachi 
Published: November 2023

BACKGROUNDLeptin is an adipokine with a central role in energy homeostasis and appetite regulation. Increases in leptin suppress appetite, while decreases in leptin increase appetite and may consequently cause weight gain. Patients with established obstructive sleep apnea (OSA) have been shown to have elevated leptin. Also, newly diagnosed OSA patients have a history of significant recent weight gain. Repetitive nocturnal intermittent hypoxia has been implicated in OSA pathophysiology and in increases in leptin. However, the factors contributing to weight gain in OSA are not completely understood. In contrast to the history of weight gain in OSA subjects, animal models of intermittent hypoxia (IH) are associated with weight loss along with increases in leptin. Furthermore, acute altitude dependent hypoxia in humans has also been associated with loss of appetite and increases in leptin. We postulated that the duration of IH may be important in defining the nature of effects on leptin. In this study we sought to examine the interactions between IH and leptin secretion, comparing acute versus chronic exposure to IH. We tested the hypothesis that although acute IH increases leptin secretion and likely suppresses appetite, repeated chronic exposure to IH will decrease leptin secretion, and thereby may increase appetite and predispose individuals such as patients with OSA to weight gain.METHODSWe used an in‐vitro approach to examine the acute effects of IH (24 cycles of 30 min 0.1% O2 followed by 30 min exposure to 21% O2) in differentiated human white preadipocytes. Cells grown in normoxic conditions and continuous hypoxia were controls for these experiments. For chronic treatment, cells were exposed to 9 cycles of IH each day for 7 days. Leptin secretion was measured in 48 h conditioned media by ELISA.RESULTSAcute 24 hour exposure to IH or sustained hypoxia increased leptin secretion (p = 0.013). However, chronic 7 day exposure of differentiated human white preadipocytes caused decreases in leptin secretion (p = 0.02).CONCLUSIONAcute intermittent hypoxia elicits increases in leptin secretion. Conversely, chronic IH decreases leptin secretion, suggesting a mechanism for development of obesity in the early stages of OSA. We speculate that decreased leptin, as a consequence of chronic IH, would result in increased appetite and hence weight gain. As obesity progresses, leptin levels likely rise secondary to the increase in body fat. Elevated leptin levels in patients with longstanding OSA may be indicative of increased fat mass and not a consequence of IH‐mediated effects on adipocytes.Support or Funding InformationChristiane Becari was supported by a grant from CNPq Brazil (# 203802/2014‐4); Prachi Singh was supported by AHA scientist development grant (11SDG7260046).
Cardioprotective Intermittent Hypoxia Conditioning Induces Glyoxalase‐1 in Rat Left Ventricle
Authors: Ramani Azaan , Scott Gary F. , Williams Arthur G. , Ryou Myoung‐Gwi , Mallet Robert T. 
Published: November 2023

BackgroundIntermittent, normobaric hypoxia (IH) conditioning increases myocardial resistance to subsequent ischemia‐reperfusion, resulting in near‐prevention of myocardial infarct and ventricular tachyarrhythmias after coronary artery occlusion and reperfusion. The cardioprotective mechanisms of IH are unknown. Myocardial ischemia‐reperfusion triggers overproduction of the powerful dicarbonyl glycating agent, methylglyoxal (MG), which injures cells by modifying arginyl and lysyl residues and, thus, inactivating enzymes and other proteins. The glyoxalase system detoxifies the modest amounts of MG normally generated by glycolysis, but this system may be insufficient to manage the excessive MG production induced by ischemia‐reperfusion. The enzyme components of this system are expressed and synthesized in response to reactive oxygen species, which are generated in myocardium by cyclic hypoxia‐reoxygenation.PurposeThis study evaluated IH induction of glyoxalase‐1 (GLO‐1), the rate‐controlling enzyme in the MG‐detoxifying glyoxalase cycle.MethodsSprague‐Dawley rats (n=10) were conditioned by a 20 day IH program consisting of 5–8 daily, 5–10 min cycles of hypoxia (9.5–10% inspired O2) with intervening 4 min room air exposures, previously shown to produce robust cardioprotection [Exp Biol Med 2004;229:806–812; Basic Res Cardiol 2006;101:436–446]. Control rats (n=10) completed sham‐conditioning with 21% O2. 24 h after the last IH or sham session, left ventricles were harvested, flash‐frozen in liquid N2 and extracted for enzyme analyses.ResultsGLO‐1 activity (U/mg protein) was increased threefold in myocardium of IH (0.53±0.08) vs. sham (0.17±0.06) rats (P<0.01), while activity of the antioxidant enzyme glutathione reductase was unchanged (IH: 0.0154±0.0057; sham: 0.023274±0.0043).ConclusionIH augments the heart's anti‐glycation defenses, which may contribute to IH‐induced cardioprotection against ischemia‐reperfusion.Support or Funding InformationFunding: NINDS NS076975; NCCAM AT003598
Physiology and Structure of Motion Sensitive Neurons in the Dragonfly Visual System
Authors: Shapiro Benjamin Goodman 
Published: November 2023

Aeshnid dragonflies are among the largest North American insects and also among the fastest and most accurate predators. During prey pursuit, they quickly respond to deviations in their flying‐prey trajectory and alter their flight paths to intercept their quarry. Remarkably, a deviation in the prey's path results in a dragonfly turn in only 30 ms, much faster than the visual latencies in most animals. Visual neurons, called target‐selective descending neurons (TSDNs) are hypothesized to mediate the dragonfly's fast response to flying prey. Once stimulated, these neurons send signals down the nerve cord to the wing‐motor circuitry controlling flight, allowing for a flight path correction. In laboratory experiments with restrained dragonflies, TSDN activity is relatively weaker and slower than expected from the behavior. We are testing the idea that this neural “lethargy” is due to the lack of neuromodulators such as octopamine in the restrained dragonfly's brain. We are investigating this hypothesis by comparing TSDN visual responses before and after injection of the octopamine mimic, chlordimeform. Our results show dramatic increases in TSDN spike activity after chlordimeform injection, suggesting that TSDN activity is augmented in the behaving animal by the neuromodulator, octopamine.Further, utilizing intracellular recording techniques, we aim to identify the individual neurons which mediate responses to specific types of stimuli, such as approaching objects. Once a cell is identified, we will inject a dye through the recording microelectrode, which will travel within the cell in question up into the brain. This will allow us to obtain a structural representation of the neuron, which can then be linked back to its specific function in the visual processing cascade.Support or Funding InformationFunded in part by a Student Research Grant from Union College.Special thanks to Prof. Robert Olberg, Biology Department, Union College