bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inspiratory Muscle Strength Training for Sleep‐related Breathing Disorders
Authors: Barrera Guadalupe Ramos , De Asis Roxanne , Bailey E. Fiona 
Published: November 2023

We have shown previously that inspiratory muscle strength training (IMST) lowers blood pressure in healthy, college‐aged adults (Vranish and Bailey 2015) and in adults with mild and moderate obstructive sleep apnea (OSA) (Vranish and Bailey 2016). The mechanism underlying IMST‐related declines in blood pressure remains unclear moreover, it is unclear if individuals with more severe forms of OSA can benefit from the intervention. Here, we explore the potential for IMST to modulate blood pressure, baroreflex sensitivity (BRS) and heart rate in normotensive and hypertensive adults who have been diagnosed with moderate and severe OSA and who are unable or unwilling to comply with standard CPAP therapy.Nine adults (5 men, 4 women) ages 54–80 years (68.5± 9.37 years) with an average AHI of 29±9.35 have been recruited to the study. Pre‐ and post‐ assessment measures include in‐home sleep studies (ApneaLink Air, ResMed), 24 hour non invasive blood pressure monitoring (SOMNOtouch, Germany), ECG, resting BRS, muscle sympathetic nerve activity (MSNA) and spirometry. Additionally, all subjects complete the Pittsburgh Sleep Quality Index. Following pre assessment, subjects are randomly assigned to IMST (n=4; 75% maximal inspiratory pressure) or sham training (n=5; 15% maximal inspiratory pressure) groups and performed in home training (30 breaths/day, 7 days/week for 6 weeks) using the K3 Series POWERbreathe trainer (Warwickshire, UK). Each subject's pulmonary function, maximal inspiratory pressure (PImax), resting blood pressure and BRS are reassessed at the beginning of each training week (1–6).Preliminary findings show decreases in resting systolic (128.33± 19.66 mmHg vs. 118± 19.67 mmHg) and diastolic blood pressures (74 ± 8.56 mmHg vs. 69.91 ±9.39 mmHg) pre vs. post for the IMST group. Blood pressures in sham trained subjects are unchanged (systolic 131.66 ± 8.79 mmHg vs. 136.16 ± 16.93 mmHg and diastolic 69.66 ± 7.72 mmHg vs. 72.33 ± 15.34 mmHg pre vs. post). Surprisingly, we see no effect of the intervention on either heart rate, BRS or MSNA. Our preliminary data indicate that whereas 6 weeks of IMST is effective in lowering blood pressure in adults with moderate to severe OSA however, the improvement in blood pressure cannot be attributed to increases in baroreflex sensitivity or to decreases in sympathetic outflow. Data collection is ongoing with target recruitment of 15 subjects for IMST and sham training groups.Support or Funding InformationAHA 16GRNT26700007
The α7/α4β2 nAChRs Alleviate The Hypotension And Altered Cardiac Sympathovagal Balance Evoked By Endotoxemia In Male Rats
Authors: Sallam Marwa Y , El‐Gowilly Sahar M , El‐Gowelli Hanan M , El‐Mas Mahmoud M 
Published: November 2023

Nicotine favorably influences inflammatory conditions such as endotoxemia and ulcerative colitis through the activation of the cholinergic antiinflammatory pathway. In this communication, we hypothesized that α7 and/or α4β2 nicotinic acetylcholine receptors (nAChRs) protect against the cardiovascular and autonomic imbalances caused by endotoxemia. Experiments were performed in conscious male rats to assess the dose‐effect relationships for i.v. nicotine (25, 50, or 100 μg/kg), PHA‐543613 (selective α7 nAChR agonist; 0.2 or 2.0 mg/kg), or 5‐iodo‐A‐85380 (5IA, selective α4β2 nAChRs agonist; 0.01 or 0.1 mg/kg) on cardiovascular responses elicited by lipopolysaccharide (LPS, 10 mg/kg i.v.). The two lower doses of nicotine (25 and 50 mg/kg) caused significant and dose‐dependent attenuation of the hypotensive and tachycardic responses caused by prior LPS administration. The effects of the 100 mg/kg dose of nicotine were comparable to those caused by the 25 mg/kg dose. The reductions in the time‐ domain indices of heart rate variability (HRV) and spectral measure of cardiac sympathovagal balance (ratio of the low‐frequency to high‐frequency power) induced by LPS were similarly reversed by nicotine. Alternatively, the hypotensive and tachycardic effects of LPS were (i) partly and dose‐dependently reversed after selective activation of α7 or α4β2 nAChRs by PHA or 5IA, respectively, and (ii) completely eliminated after treatment with a mixture of the smaller doses of the two agonists. By contrast, the individual or combined use of PHA or 5IA fully abolished the LPS‐evoked reductions in the low‐frequency/high‐frequency ratio, indicating the normalization of the cardiac sympathovagal balance. Together, the data implicate monomeric (α7) and heteromeric (α4β2) nAChRs in the nicotine counteraction of the adverse cardiovascular effects of endotoxemia.Support or Funding InformationSupported by the Science and Technology Development Fund, Egypt (STDF Grant No. 14895).
A Reduction in SK Channel Function Contributes to Increased Excitability of Hypothalamic Magnocellular Neurons During Heart Failure
Authors: Neto Hildebrando Candido Ferreira , Biancardi Vinicia , Stern Javier 
Published: November 2023

Neurohumoral activation, which includes elevated plasma levels of vasopressin, is a hallmark of heart failure (HF) and contributes to morbidity and mortality in this disease. Here, we evaluated whether changes in Ca2+‐activated K+ (SK) channels contribute to enhanced hypothalamic magnocellular neurosecretory cell (MNCs) activity in HF rats. Whole‐cell patch clamp recordings obtained from MNCs in slices from Sham and HF rats showed that the spike frequency evoked by direct current injection was significantly higher in the HF rats compared to Sham rats (Sham 16±0.9 vs HF 24±1.2 spikes, p<0.001). Bath application of the SK channel blocker apamin significantly increased the evoked firing frequency in MNCs from Sham rats, but no effect was observed in HF rats (Sham 23±0.9, p< 0.05 vs control; HF 26±0.7 spikes, p>0.05 vs control). The medium afterhyperpolarization potential (mAHP) following a train of spikes was significantly smaller in MNCs from HF rats compared to Sham rats (Sham 9.7±1.1 vs HF 6.6±0.6 mV, p<0.05) and apamin reduced the mAHP in both groups (Sham 2.9±0.5 vs HF 1.6±1.1 mV). Voltage‐clamp recordings of SK tail currents revealed that the apamin‐sensitive current amplitude and area were significantly smaller in MNCs from HF rats (amplitude: Sham 0.2±0.03 vs HF 0.09±0.03 nA, p<0.05; area: Sham 15.4±2.5 vs HF 7.2±1.2 nA.ms, p<0.01) whereas intracellular dialysis of MNCs with BAPTA reduced the currents in both groups to the same extent. No significant differences were observed in cell capacitance (Sham 30±2 vs HF 26±3 pF, p>0.05) or input resistance (Sham 960±87 vs HF 945±167 MΩ, p>0.05) between groups. Taken together, our data indicates that a decrease in SK channel function/activity and/or expression contributes to the increased excitability of MNCs in HF rats.Support or Funding InformationNIH R01HL090948
Water deprivation does not enhance sympathetic and pressor responses to sciatic nerve stimulation or chemical activation of RVLM neurons
Authors: Stocker Sean D , Wenner Megan M , Farquhar William B 
Published: November 2023

Water deprivation produces a volume contraction and elevation in plasma sodium concentrations and osmolality. Together, these changes activate the sympathetic nerve activity (SNA) to support arterial blood pressure (ABP). Prior studies suggest that dietary salt intake raises plasma sodium concentrations to sensitize central autonomic networks including the rostral ventrolateral medulla (RVLM), exaggerate sympathetic reflexes, and increase blood pressure variability. The purpose of the present study was to examine whether water deprivation produced similar changes in RVLM neurons and enhanced sympathetic responses from activation of sciatic afferent nerves. Male Sprague‐Dawley rats (300–450g) were deprived of water but not food for 48h. Control rats were given free access to both. Then, animals were anesthetized with Inactin (120mg/kg, IV), artificially‐ventilated, and prepared for recording brachial ABP and SNA. Sciatic afferents were electrically stimulated (500uA, 1s pulse, 5s duration) at various frequencies (2, 5, 10, and 20 Hz). Water deprivation (H2OD) vs control rats significantly elevated plasma sodium concentrations (143±1 vs 137±1 mM, respectively; P<0.01) and osmolality (310±4 vs 294±2 mOsm/L, respectively; P<0.01). Activation of sciatic afferents produced frequency‐dependent increases in all variables in both control and water‐deprived animals. However, there were no statistical differences at any frequency between groups in mean ABP (5Hz ‐ control: 18±3 mmHg vs H2OD: 21±2 mmHg; n=6–8), lumbar SNA (5Hz – control: 139±11% vs H2OD: 129±10%, n=6–8), renal SNA (5Hz – control: 169±20% vs H2OD: 178±18%, n=6–8 per group), or splanchnic SNA (5Hz – control: 163±17% vs H2OD: 162±5%, n=6–8 per group). In a second set of experiments, chemical stimulation of RVLM neurons by microinjection of L‐glutamate (10mM, 35nL) produced significant increases in SNA and ABP in control and water‐deprived groups; however, there were no significant differences in mean ABP (control: 15±4mmHg vs H2OD: 11±2mmHg; n=4 per group), lumbar SNA (control: 124±4% vs H2OD: 131±10%), renal SNA (control: 133±5% vs H2OD: 131±4%), or splanchnic SNA (control: 131±3% vs H2OD: 140±17%). Inhibition of RVLM by unilateral injection of GABA (100mM, 35nL) produced similar decreases in mean ABP (control: ‐31±3mmHg vs H2OD: −29±2mmHg; n=3–4 per group), lumbar SNA (control: −26±1% vs H2O: −27±8%), renal SNA (control: −41±8% vs H2OD: −30±7%), and splanchnic SNA (control: −39±11% vs H2OD: −43±7%). Collectively, these findings suggest that water deprivation raises plasma sodium concentrations and osmolality but does not alter sympathetic reflexes or alter the excitability of RVLM neurons.Support or Funding InformationAHA Established Investigator Award (SDS), NIH R01 HL113270 (SDS), NIH R01 HL128388 (SDS, WBF)
Enhanced Excitability of Vasopressin Neurons in the Supraoptic Nucleus Following 48 hr. Water Deprivation
Authors: Farmer George E. , Little Joel T. , Knapp Blayne , Cunningham J. Tom 
Published: November 2023

Arginine vasopressin (AVP) is a neurohypophyseal hormone released from the posterior pituitary by magnocellular neurosecretory cells (MNCs) located within the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus. AVP is involved in the regulation of body fluid homeostasis and influences blood pressure, plasma osmolality, and blood volume. The regulation of AVP release is critical for body fluid homeostasis and is dependent on the activity of MNCs. However the cellular mechanisms leading to changes in AVP release are not fully understood. Water deprivation (WD), a progressive physiological challenge, was used to examine changes in excitatory neurotransmission in MNCs using patch‐clamp electrophysiology. Male Sprague‐Dawley rats weighing 250 – 350 g received bilateral SON infusions of an adeno‐ associated virus (AAV) construct containing AVP gene promoter and GFP reporter using isoflurane anesthesia. Two weeks following AAV infusions, rats were water deprived for 24 hr. or 48 hrs. Controls were always allowed ad libitum access to water. For electrophysiological experiments, rats were anesthetized with isoflurane and coronal brain slices (300 μm) containing the SON were prepared using standard procedures. Whole‐cell patch clamp recordings were obtained from slices superfused with aCSF containing tetrodotoxin (TTX; 0.5 μM) and bicuculine methbromide (Bic; 10 μM). Following baseline mEPSCs recordings, individual NMDAR and AMPA mediated components were pharmacologically isolated with 5 minutes drug application of AMPA antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX; 10uM) or the NMDAR antagonist 2‐amino‐5‐phosphonopentanoic acid (APV; 50 uM). Parameters measured for mEPSCs were amplitude (pA), rise time (ms), decay time (ms), charge transfer, and mEPSC frequency. In GFP labeled SON neurons (i.e. confirmed vasopressinergic neurons), 24 (n = 9; P < 0.05) and 48 hr (n = 9; P <0.05) water deprivation increased the frequency of mEPSCs when compared to controls (n = 13). In cells from the 48 hr WD group, the increase in frequency was accompanied by a reduction in amplitude. The increase in frequency associated with both 24 and 48 hr WD was mediated by an increase of AMPA mediated EPSCs (p < 0.05) whereas the reduction in amplitude specific to 48 hr WD was mediated by a reduction in the amplitude of NMDA mediated EPSCs (p < 0.05). The results suggest that water deprivation may be associated with presynaptic mechanisms that increase AMPA excitatory events that after 48 hr may also be associated with postsynaptic mechanisms that reduce NMDA excitation. Further studies are necessary to understand the individual AMPA and NMDA receptor mechanisms contributing to increases in SON excitability and subsequent vasopressin release in response to water deprivation.Support or Funding InformationSupported by R01 HL119458‐04
Maternal High Fat‐High Sucrose Diet is Associated with Elevated Offspring Hypothalamic Oxidative Stress and Blood Pressure Responses to Psychological Stress.
Authors: Jayaratne Sachini , Prestipino Louise , Polson Jaimie W 
Published: November 2023

There is mounting evidence that diets high in fat and sucrose (HFS) during pregnancy adversely affect offspring cardiovascular health. The aims of the present study were to assess the level of oxidative stress (OS) in brainstem cardiovascular control sites and compare blood pressure (BP) responses to psychological stress in HFS and control offspring.Dams were fed a HFS diet (21% fat, 34% sucrose; control, 4.8% fat, 0% sucrose) from 4 weeks prior to mating until weaning. Three‐month old male offspring (n=7) were assessed for levels of the antioxidant glutathione and the OS marker protein carbonyl (PCs) in brainstem cardiovascular nuclei. At 9–12 months, cardiovascular variables were acquired from both males (control n=5; HFS=6) and females (control n=4; HFS=3) at rest and in response to mild (air jet, AJ) and moderate (restraint, RS) psychological stress using telemetry. Male rats were perfused and brains were processed immunohistochemically for Fos protein expression. Data are expressed as mean ± SE, statistical significance was taken as p<0.05.HFS offspring exhibited increased retroperitoneal adiposity as a percentage of wet weight (2% vs 3.7%). Markers of OS were elevated in the hypothalamus, comprising a two‐fold increase in PCs and 40% reduction in glutathione. No significant differences were observed in the medulla or midbrain of programmed offspring.Resting mean blood pressure (BP) was higher in both male and female HFS offspring than controls (male; 102.0±3.0 vs 94.2±2.6 mmHg, female; 104.4±3.7 vs 93.1±2.9 mmHg). BP responses to psychological stress were also enhanced. In HFS males, both stressors elicited greater initial increases in systolic BP (AJ; +30±3.3 vs +17±2.1 mmHg, RS; +39±1.9 vs +26±2.8 mmHg), while recovery was slower in AJ only (45 min post‐AJ, +13±1.6 vs +3±2.4 mmHg from baseline). A larger increase in blood pressure variability (low frequency component) was also observed in HFS males during both stressors, while no difference in heart rate or heart rate variability was observed between groups.In HFS females, the initial systolic BP response to RS was greater (+41.3±1.9 vs 33.3±0.9 mmHg), however, there was no difference in AJ (HFS, 25.0±2.3 vs 24.3±4.3 mmHg). In contrast to males, recovery was similar to controls in HFS females.HFS offspring also showed reduced Fos expression in the midbrain periaqueductal grey (PAG) in response to stress. Following AJ, the number of Fos‐positive neurons was reduced by ~40% in the lateral and ventrolateral PAG, while post‐RS a decrease in Fos expression was observed in the dorsomedial (70% reduction), dorsolateral (43%) and lateral (47%) PAG. No difference in Fos expression was observed in the hypothalamus.The results suggest that maternal HFS elicits increased OS in the hypothalamus of offspring and programs a pro‐hypertensive phenotype characterised by exaggerated cardiovascular responses to psychological stress.
Endogenous Annexin‐A1 is a Protective Determinant in HFD‐induced Insulin Resistance and Diabetic Nephropathy
Authors: Purvis Gareth S.D. , Chiazza Fausto , Collino Massimo , Solito Egle , Thiemermann Chris 
Published: November 2023

IntroductionType‐2 diabetes mellitus is a key driver of cardiovascular disease often leading to renal failure, infarction or stroke. Here we investigate the role of Annexin‐A1 (ANXA1), an endogenous anti‐inflammatory peptide, in a mouse model of high‐fat diet (HFD) induced insulin resistance and diabetic nephropathy.Methods10‐week old male C57BL/6 (wild‐type) and ANXA1 null (ANXA1−/−) mice were fed a normal (chow) diet or high‐fat high‐sugar (HFD) diet for 10 weeks. Mice were administrated either human recombinant (hr) ANXA1 (1 μg hrANXA1, Hepes buffer, i.p.) or vehicle (100 μl Hepes buffer, i.p.) from weeks 5–10 of dietary manipulation.ResultsWhen compared to WT‐mice fed on chow diet, WT‐mice fed on HFD exhibited significantly lower serum levels of ANXA1 (1.259±0.01 vs. 1.154±0.03 ng/ml, P<0.05) and reduced ANXA1 expression in the kidney (0.96±0.02 vs. 0.30±0.04 O.D, P<0.05). When compared to WT‐mice fed on chow diet, WT‐mice fed on HFD and subjected to OGTT demonstrated a significant impairment in their oral glucose tolerance test (OGTT; AUC analysis: 84.42±4.51 vs. 110.70±3.89, P<0.05), which was improved with hrANXA1 treatment (110.70±3.89 vs. 89.40±0.99, P<0.05). The OGTT of ANXA1−/− mice fed on HFD was significantly worse than that of WT‐mice. When compared to WT‐mice fed on chow diet, WT‐mice fed on HFD demonstrated a significant increase in albumin‐to‐creatinine (ACR) ratio (20.75±2.434 vs. 56.10±5.80 mg/mg, P<0.05), suggesting the development of proteinuria, which was improved with hrANXA1 treatment (56.10±5.80 vs. 35.28±6.04 mg/mg, P<0.05). ANXA1−/− mice fed on HFD demonstrated a significant increase in ACR compared to WT‐mice fed on HFD (56.10±5.80 vs. 79.38±4.33 mg/mg, P<0.05) suggesting more severe proteinuria. When compared to WT‐mice fed on chow diet, WT‐mice fed on a HFD had decreased phosphorylation Ser188 of RhoA in the liver (1.00±0.004 vs. 0.575±0.002 O.D, P<0.05) and kidney (0.95±0.02 vs. 0.030±0.04 O.D, P<0.05) which was associated with increased phosphorylation of MYPT1 (liver, 1.15±0.006 vs. 4.15±0.07 O.D, P<0.05; kidney, 1.025±0.09 vs. 2.60±0.09 O.D, P<0.05). Both of these signalling events was prevented by treatment with hrANXA1. Interestingly, ANXA1−/− mice demonstrated constitutively activated RhoA and phosphorylation of MYPT1 suggesting that ANXA1 could be a major regulator of this GTPase activity.ConclusionWe have shown for the first time that ANXA1 expression is reduced in a mouse model of HFD‐induced insulin resistance and diabetic nephropathy. This down‐regulation removes an important tissue‐protective factor allowing for exacerbation of renal dysfunction, which can be attenuated with treatment with hrANXA1. Most notably, hrANXA1 reduces both the metabolic derangements and the renal dysfunction associated with T2DM.Support or Funding InformationThis work is funded by the Britsish Heart Foundation grant number FS/13/58/30648.
Evidence for Mitochondrial AT2 Receptor‐Mediated Inhibition of Intracellular Angiotensin II‐induced Respiratory and Glycolytic Responses in Mouse Proximal Tubule Cells
Authors: Li Xiao Chun , Zhuo Jia Long 
Published: November 2023

It is well recognized that endocrine and paracrine angiotensin II (ANG II) is involved in mitochondrial dysfunction in cardiovascular, renal and hypertensive diseases, but whether intracrine or intracellular ANG II plays an important role in the regulation of mitochondrial function remains virtually unknown. We hypothesize that in addition to activation of its cell surface receptors, ANG II and its receptors are internalized and trafficked to the mitochondria, where it may induce significant mitochondrial respiratory and glycolytic responses. As a proof of concept study, we constructed adenoviral vectors encoding an intracellular ANG II fusion protein, ECFP/ANG II (a gift from Dr. Julia Cook of Ochsner Health System), or a GFP‐tagged AT2 receptor, AT2R/GFP, a mitochondria targeting sequence, and a proximal tubule cell‐specific sglt2 promoter for proximal tubule‐ and mitochondria‐specific overexpression of mito‐ECFP/ANG II or mito‐AT2R/GFP in cultured mouse proximal tubule (mPCT) cells (a gift from Dr. Ulrich Hopfer of Case Western Reserve University). The mitochondrial respiratory and glycolytic responses to overexpression of mito‐ECFP/ANG II or mito‐AT2R/GFP were measured using Seahorse XF Cell Mito and XF Glycolysis Stress Test Kits, respectively. Fluorescent microscopic imaging revealed robust overexpression of mito‐ECFP/ANG II and/or mito‐AT2R/GFP in mPCT cells 48 h after transfection, and confirmed their colocalization with a mitochondrial marker MitoTracker® Red FM. Overexpression of mito‐ECFP/ANG II alone markedly increased oxygen consumption rate (OCR) (Control: 130.4 ± 8.2 vs. mito‐ECFP/ANG II: 232.3 ± 10.6 pmol/min; p<0.01, n=10) and extracellular acidification rate (ECAR) (Control: 8.8 ± 0.3 vs. mito‐ECFP/ANG II: 11.8 ± 1.3 mpH/min; p<0.01, n=10), respectively. The AT1 receptor blocker losartan (10 μM) completely blocked the effects of mito‐ECFP/ANG II on OCR and ECAR, whereas the AT2 receptor blocker PD123319 (10 μM) had no significant effect. However, overexpression of mito‐AT2R/GFP with mito‐ECFP/ANG II in mPCT cells significantly attenuated the effects of mito‐ECFP/ANG II on OCR (119.4 ± 10.5 pmol/min; p<0.01 vs. mito‐ECFP/ANG II, n=10) and ECAR to control (5.4 ± 0.37 mpH/min, p<0.01 vs. mito‐ECFP/ANG II, n=10). Interestingly, PD123319 significantly blocked the effects of mito‐ECFP/ANG II and mito‐AT2R/GFP overexpression on OCR (184.5 ± 4.3 pmol/min; p<0.01 vs. mito‐ECFP/ANG II and mito‐AT2R/GFP, n=5) and ECAR (8.2 ± 0.31 mpH/min, p<0.01 vs. mito‐ECFP/ANG II and mito‐AT2R/GFP, n=5). Our results strongly support the proof of concept that activation of AT1 receptors by ANG II in the mitochondria stimulates, whereas activation of AT2 receptors by ANG II in the mitochondria inhibits, mitochondrial respiratory and glycolytic responses in mouse proximal tubule cells.Support or Funding InformationThis work was supported in part by 2R01DK067299, 1R01DK102429, and 1R56HL130988.