bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vascular Endoplasmic Reticulum Stress Does Not Contribute To Exacerbated Organ Damage And Mortality In Smooth Muscle Cell BK Channel Deficient Septic Mice
Authors: Xu Hui , Wang Youping , Fernandes Roxanne , Fink Gregory D , Galligan James J 
Published: November 2023

Smooth muscle cell (SMC) BK channel deficient (BK channel β1‐subunit knockout, BK β1‐KO) mice have disrupted SMC intracellular Ca2+ homeostasis and increased sensitivity to polymicrobial sepsis‐induced organ damage and mortality. Here we evaluated the contribution of vascular endoplasmic reticulum (ER) stress to the exacerbated organ damage and mortality. At 24 hours post‐cecal ligation/puncture, the mortality was greater in BK β1‐KO vs wild‐type (WT) mice. Expression of ER stress protein indicators (immunoglobulin‐heavy‐chain‐binding protein, Bip; protein disulfied isomerase, PDI; inositol‐requiring kinase‐1α, IRE‐1α; and 94‐kilodalton glucose regulated protein, GRP94) in mesenteric arteries was similar in all septic and non‐septic control mice. Expression of C/EBP homologous protein (CHOP), a transcriptional factor of apoptosis, was undetectable in mesenteric arteries from all control and septic mice, but CHOP expression was detected in arteries from control mice treated with tunicamycin, an ER stress inducer. In saline‐resuscitated septic mice, treatment with ER stress antagonists (tauroursodeoxycholic acid and 4‐phenylbutyric acid) did not protect against the exacerbated hypothermia, organ damage and mortality in BK b1‐KO mice. 4‐phenylbutyric acid even exacerbated mortality in septic WT mice. Our data indicate that ER stress is not responsible for the worsened organ damage and mortality observed in mice with vascular BK channel deficiency.Support or Funding InformationNational Heart, Lung and Blood Institute (P01 HL070687 for H.X., J.J.G., and G.D.F.) and the American Heart Association Midwest Affiliate (11GRNT6690010 for H.X.).
Endothelin‐1 Blocks BK Channels by Stimulating Protein Kinase C‐Mediated Rab11A Phosphorylation at Serine 177 in Arterial Smooth Muscle Cells
Authors: Zhai Xue , Leo M. Dennis , Jaggar Jonathan H. 
Published: November 2023

Large‐conductance calcium (Ca2+)‐activated potassium channels (BK) composed of BKα and auxiliary β1 subunits control arterial myocyte contractility. BKα subunits are primarily plasma membrane‐localized, whereas β1 subunits are stored within intracellular Rab11A‐positive recycling endosomes in arterial myocytes. Nitric oxide (NO) stimulates rapid surface trafficking of auxiliary β1 subunits, which stimulates BK channels, leading to vasodilation. Vasoconstrictors, including endothelin‐1 (ET‐1), inhibit BK channels but mechanisms involved are unclear. Here, using surface biotinylation and immunoFRET microscopy, we found that ET‐1 attenuated NO‐induced surface trafficking of β1 subunits in cerebral artery myocytes. Bisindolylmaleimide‐1 (BIM‐1), a protein kinase C (PKC) inhibitor, blocked this inhibitory effect of ET‐1. Bioinformatic analysis found five potential PKC phosphorylation sites on Rab11A, of which Ser177 had the highest probability. Arterial transfection with a S177A Rab11A mutant blocked ET‐1‐inhibition of β1 surface trafficking. Patch‐clamp experiments indicated that ET‐1‐inhibition of β1 trafficking reduced the ability of NO to increase BK channel open probability (Po). The S177A Rab11A mutant attenuated ET‐1 inhibition of both single BK channel Po and Ca2+ spark‐induced transient BK currents. In summary, our data indicate that ET‐1 stimulates PKC‐mediated phosphorylation of Rab11A at serine 177, which blocks surface trafficking of β1 subunits, leading to BK channel inhibition in arterial myocytes.Support or Funding InformationNIH/NHLBI grants HL67061 and HL110347
Impaired BKCa channel function in native vascular smooth muscle from diabetic patients
Authors: Nieves‐Cintron Madeline , Buonarati Olivia R , Rigor Robert , Sasse Kent C , Ward Sean M , Hell Johannes W , Navedo Manuel F 
Published: November 2023

Increased vascular tone and impaired vascular function are major complications during diabetes. Large‐conductance Ca2+‐activated potassium (BKCa) channels are important regulators of vascular smooth muscle cell contractility and arterial tone. Whereas multiple reports indicate that BKCa channel function is impaired in murine models of diabetes and in immortalized cell lines from diabetic human subjects, whether a similar alteration occurs in native vascular smooth muscle cells from diabetic patients has not been clearly established. Here, we examine and compared BKCa channel function in native vascular smooth muscle cells from obese non‐diabetic and diabetic patients undergoing bariatric surgery using patch‐clamp electrophysiology and confocal microscopy. We found that the amplitude and frequency of spontaneous transient outward currents (STOCs), which are produced by the activation of BKCa channels coupled to Ca2+ sparks, are significantly decreased in human diabetic cells. Ca2+ sparks amplitude and frequency was not different between human non‐diabetic and diabetic cells, indicating that impairment in STOC activity occurs at the BKCa channel level. Consistent with this, BKCa channels in human diabetic cells showed an apparent reduction in Ca2+ sensitivity as compared to non‐diabetic cells. These results suggest impaired BKCa channel function due to aberrant Ca2+ sensitivity in native vascular smooth muscle cells from diabetic patients, which may contribute to the development of vascular complications in humans with diabetes.Support or Funding InformationThis work was supported by grants NIH‐HL098200 and NIH‐HL121059, and AHA‐14GRNT18730054 to MFN.
HuR‐mediated HK2 Downregulation Leads to Coronary Endothelial Dysfunction in Diabetic Mice
Authors: Wang Weihua , Truong Aaron H. , Makino Ayako 
Published: November 2023

Ischemic heart disease is the leading cause of mortality in diabetes mellitus and coronary endothelial dysfunction is implicated in the development and progression of cardiac ischemia. HuR (Human antigen R, also known as ELAVL1) is an RNA binding protein which binds to and stabilizes mRNAs that contain AU‐rich elements in 3′‐UTRs. HuR is ubiquitously expressed and regulates many cellular functions via altering mRNAs’ stability. In this study, we explore the role of HuR in coronary endothelial dysfunction in diabetic mice. Type 1 diabetes was induced in mice by high‐dose streptozotocin (STZ) injection and type 2 diabetes by low‐dose STZ injection with high‐fat diet. Mouse coronary endothelial cells (MCECs) were isolated using magnetic beads coated with CD31. The protein levels of HuR in the nuclear and cytosolic fraction were assessed by immunofluorescence staining and western blot. Ribonucleoprotein immunoprecipitation (RIP) was performed to determine the binding of our focus RNAs to HuR in ribonucleoprotein (RNP) complexes. Mitochondrial calcium concentration was measured by Rhod2‐AM staining. Our western blot data demonstrate that MCECs isolated from diabetic mice exhibited significantly lower concentration of HuR in the nuclear fraction, but not in cytoplasm, compared to control. We also confirmed that nuclear HuR expression was markedly reduced in diabetic MCECs using immunofluorescence staining. We predicted the target mRNAs of HuR and performed RIP for those mRNA. Among the mRNAs which we tested, hexokinase 2 (HK2) mRNA was detected in the RNP complex of HuR. Furthermore, we found that the binding of HuR to HK2 mRNA was significantly decreased in MCECs isolated from diabetic mice compared to control. Mitochondrial calcium concentration and the protein expression of voltage dependent anion channel (VDAC), which modulates calcium uptake into mitochondria, were significantly increased and HK2, an endogenous negative regulator of VDAC, was significantly decreased in diabetic MCECs in comparison to control. In addition, HK2 overexpression in diabetic MCECs attenuated mitochondrial calcium uptake toward control levels. In conclusion, our data suggest that decreased HuR level in the nucleus reduces the stability of HK2 mRNA, downregulates HK2 protein expression, and subsequently increases mitochondrial calcium uptake in diabetic MCECs. HuR might be a potential therapeutic target for ischemic heart disease in diabetic patients via restoring coronary endothelial function.Support or Funding InformationThis work was supported by National Heart, Lung, and Blood Institute Grant R01 HL‐115578 (A. Makino)
Effects of Homocysteic Acid and Estrogen on Behavior in Female Rats
Authors: Barney Chris C. , Loubser Lize , Samuel Shirly , Chase Leah A. 
Published: November 2023

Homocysteic acid (HCA) is a neurotoxin that can over stimulate NMDA receptors, leading to neuronal cell death. In humans, hyperhomocystemia, which can lead to elevated HCA levels, has been associated with a variety of disorders, including schizophrenia, depression, Alzheimer's disease, and Parkinson's disease. Previous studies in our laboratory have shown that neonatal administration of HCA causes behavioral changes in female but not male rats. The purpose of the current study study was to determine if the behavioral alterations caused by HCA in female rats were dependent on estrogen levels. Rats were administered HCA intraperitoneally for two weeks starting on day two after birth, housed singly after weaning, and ovariectomized at six and one‐half weeks of age. Half of the HCA treated and half of the control rats had silastic tubes containing estradiol proprionate implanted subcutaneously at the time of ovariectomy. Behavioral testing began three weeks later. Estrogen increased the amount of time the rats spent in the innermost zone in an Open Field Test, increased voluntary running on a running wheel, reduced the number of falls on a RotaRod, increased time to remove tails from hot water, increased saccharine intake, and increased time before giving up in the Forced Swim Test. HCA reduced ambulatory time and distance traveled in the Open Field Test, decreased the number of visits to the open arm in an Elevated Plus Maze test, reduced social interactions in a two‐cage intruder test, and reduced 24 hour retention of the memory of the hidden platform in a Morris Water Maze test. The only significant interactions between HCA and Estrogen were in the ambulatory time and distance traveled in the Open Field Test and in the time spent with the intruder in the social interaction test. This experiment demonstrated that numerous behaviors in rats are estrogen dependent but behavioral responses to HCA are not very estrogen dependent.Support or Funding InformationSupported by the Hope College Biology Department.
The Role of REM Sleep in the Development of PTSD Using a Rodent Model
Authors: Arias Yvette , Delorme James , Poe Gina 
Published: November 2023

Sleep disturbances resulting from an acute trauma predict the development of posttraumatic stress disorder (PTSD) symptoms. Sleep abnormalities can aggravate PTSD and may result in failure of extinction memory, allowing fear to persist. Currently, the electrophysiological properties of sleep that are associated with trauma are not well understood. Rapid eye moment (REM) sleep plays a critical role in memory consolidation and emotional regulation but it may be maladaptive in those experiencing PTSD. We hypothesize that normal, adaptive REM sleep following a traumatic event will lessen the severity of a PTSD‐like phenotype. Male Sprague Dawley rats were REM sleep deprived prior to (n=6) or after (n=6) a single prolonged stress (SPS) protocol (three acute stressors followed by a 7‐day isolation period) to develop a PTSD‐like phenotype, and to assess the contribution of sleep disruption to phenotype development. We evaluated freezing levels on a fear‐associated memory test to assess the severity of the PTSD‐like phenotype in the two sleep deprivation groups compared with controls who never experienced the trauma (n=6) and traumatized rats who were never sleep deprived (n=6). Interestingly, sleep deprivation after the acute phase of SPS and prior to the 7 day isolation period ameliorated the PTSD like symptom of impaired extinction recall a week later. The data suggests that REM sleep deprivation after a traumatic event reduces PTSD‐like phenotype, and that sleep disruption before the trauma exposure did not have a similar effect in rescuing the animals from the posttraumatic disorder symptoms. Our findings, preventing possibly maladaptive sleep following trauma, and timing sleep to adaptive windows normalize later fear extinction abilities. This may be beneficial as part of a treatment for PTSD and other stress associated disorders.Support or Funding InformationUPR‐PRISE NIH#R25GM096955University of Michigan SURP 2015
Failure in Central Respiratory 5HT‐Dependent Chemoreception in a Genetic Model of Epilepsy
Authors: Totola Leonardo T , Takakura Ana C , de Oliveira Jose Antonio , Garcia‐Cairasco Norberto , Moreira Thiago S 
Published: November 2023

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. There is still a debate in the literature if the respiratory arrest is the primary cause of death. Respiratory chemoreceptors neurons located in retrotrapezoid nucleus (RTN) constitute one of the main groups responsible for controlling breathing automaticity and receive a dense serotonergic innervation. Here, we ask whether alterations of a type of chemoreceptor neurons that expresses the transcription factor Phox2b and is non‐catecholaminergic (Phox2b+/TH−) could affect breathing in a rat model of tonic‐clonic seizures, with susceptibility to audiogenic seizures (the Wistar Audiogenic Rat (WAR) strain (WAR: 340–496 g, n = 6–7). The number of Phox2b+/TH−neurons in the RTN was reduced (79±11%) in WAR. The WARs have reduced resting ventilation (VE) by 35 ±10% and reduced increase in VE elicited by hypercapnia (7% CO2) by 51 ±7%. Furthermore, we also showed that the VE response to serotonin (1 mM ‐ 50 nl) into the RTN region was significantly hampered in WARs due to the reduction in the number of 5‐HT varicosities within the marginal layer of the RTN region. Our results suggest a respiratory disorder, as well as a reduction of the serotonergic neurotransmission within the RTN region, which justify to further use WAR as a suitable model to study increased risk factors and the mechanisms associated with SUDEPSupport or Funding InformationFAPESP, CNPq and CAPES/PROEX
Diastolic Dysfunction and Arrhythmia Incidence are Exacerbated by Central Chemoreflex Activation in HFpEF
Authors: Del Rio Rodrigo , Toledo Camilo , Andrade David C , Lucero Claudia , Aliaga Valentin , Marcus Noah J , Madrid Carlos 
Published: November 2023

Heart failure with preserved ejection fraction (HFpEF) is characterized by decreased ventricular compliance and autonomic imbalance. Tonic and episodic chemoreflex activation contributes to autonomic imbalance in heart failure and is associated with poor prognosis. We sought to determine if the sensitivity of central chemoreceptors (CC) is enhanced in an animal model of HFpEF, and whether acute activation of CC exacerbates cardiac dysfunction. Volume overload (a‐v anastomosis) was used to induce HFpEF in adult male Sprague‐Dawley rats. Ventilatory responses to acute hypercapnia (FiCO2‐7% in O2) were measured by plethysmography to assess CC sensitivity, and a conductance catheter was used to measure pressure‐volume relationships as a measure of cardiac function. Neuronal activation was assessed by measuring FosB expression in brainstem micropunches from pre‐sympathetic regions of the rostral ventrolateral medulla (RVLM). Ejection fraction did not differ between HFpEF and sham rats(51±3 vs. 50±7 %, HFpEF vs. sham). HFpEF rats compared to sham rats exhibited cardiac hypertrophy (heart/body weight, 6.1±0.3 vs. 4.0±0.5 mg/g, HFpEF vs. sham), pulmonary congestion (lung wet/dry weight, 4.4±0.1 vs. 3.8±0.1 g/g, HFpEF vs. sham), increased arrhythmia incidence (104±34 vs. 11±2 events/h, HFpEF vs. sham), greater ventricular stiffness (β, 7.4±1.4 vs. 4.3±0.7 mmHg/ml, HFpEF vs. sham), and decreased ventricular active relaxation (τ, 9±2 vs. 15±2 ms, HFpEF vs. sham). In HFpEF rats, CC sensitivity was increased (165.3±9.1 vs. 127.3±10.3 ml/min/100g, HFpEF vs. sham), and CC stimulation (normocapnia vs. hypercapnia) significantly increased (P<.05) arrhythmia incidence (104±34 vs. 1164±204 events/h,) and β (7.4±1.4 vs. 17.5±7.5 1/ml), but did not affect τ values (9±2 vs. 9±1 ms) or significantly compromise ventricular capacitance. RVLM activation (FosB expression) was increased in HFpEF rats compared to sham animals. Our results indicate that the CC is enhanced in in HFpEF, neuronal activation is increased in pre‐sympathetic regions of the brainstem, and acute CC activation further exacerbates diastolic dysfunction and arrhythmia incidence in HFpEF.Support or Funding InformationSupported by Fondecyt 1140275.
Increased Brain‐derived Neurotrophic Factor in Lumbar Dorsal Root Ganglia Contributes to the Enhanced Skeletal Muscle Afferent Neuronal Excitability via a MAPK‐dependent pathway in Heart Failure
Authors: Wang Hanjun , Rozanski George , Zucker Irving H. 
Published: November 2023

An exaggerated exercise pressor reflex (EPR) is associated with excessive sympatho‐excitation and exercise intolerance in the chronic heart failure (CHF) state. A previous study from this laboratory demonstrated that peripheral sensitization of the afferent limb (mainly mechanically sensitive fibers) is an important contributor to the exaggerated EPR in CHF. Here, we hypothesized that brain‐derived neurotrophic factor (BDNF) in muscle afferent neurons plays a critical role in the sensitization of muscle mechanosensitive afferents in CHF. Increased BDNF expression was observed in lumbar DRGs from CHF rats compared to sham rats (8.3±1.1 vs. 19.5±1.8 pg/g, n=6, P<0.05). Immunofluorescence data further showed a greater increase in the number of BDNF‐positive neurons especially in medium and large‐sized DRG subpopulations (mainly mechanically sensitive NF200 positive neurons) from CHF rats compared to sham rats. Patch clamp experiments demonstrated that incubation with BDNF for ~4 hours, dose‐dependently increased the number of action potential (AP) {3.1±0.7 vs. 10.4±2.3; vehicle‐treated (n=16) vs. BDNF‐treated (100 ng/ml, n=17); P<0.001} in response to the same amount of current injection (1.0 nA) in medium‐sized (mainly mechanically sensitive) muscle DRG neurons in sham rats, which was significantly blocked by co‐incubation of the mitogen‐activated protein kinases (MAPK) inhibitor PD98059 (10 μM, 4.3±0.9, n=7; P<0.01). Compared to sham rats, CHF rats exhibited an increased number of AP (14.3±2.6; n=16; P<0.001 vs. sham+vehicle) in response to 1.0 nA current injection in medium‐sized muscle afferent DRG neurons, which was significantly attenuated by 4 hours of incubation with either anti‐BDNF (10 μg/ml, 3.9±1.0; n=11; P<0.001) or PD98059 (10 μM, 5.6±1.4, n=8; P<0.01). These data suggest that increased BDNF in muscle DRG neurons contributes to the enhanced muscle mechanical afferent neuronal excitability via a MAPK‐dependent pathway in the CHF state.Support or Funding InformationThis work was supported by The American Heart Association (#12SDG12040062) and in part, by grants from the National Heart, Lung, and Blood Institute (R01 HL116608‐01A1 and PO1 HL62222).
Cardiopulmonary afferents modulate sympathetically‐mediated heart rate responses to muscle metaboreflex activation in humans
Authors: Souza Mayara C. , Teixeira Andre L. , Nunes Diego , Lopes Paulo M. , Gomes Mauricio D. , Fisher James P. , Vianna Lauro C. 
Published: November 2023

The sensory component of the exercise pressor reflex is comprised of group III and IV skeletal muscle afferents that respond to both mechanical (i.e., muscle mechanoreflex) and metabolic (i.e., muscle metaboreflex) stimuli. In humans, isolated muscle metaboreflex activation with post‐exercise ischemia (PEI) has a major effect on increasing sympathetic nerve activity. This can cause peripheral vasoconstriction and partially maintain the exercise‐induced increase in blood pressure. A smaller heart rate response is evoked, which can be blocked by antagonism of b‐1 receptor. The loading of cardiopulmonary baroreceptors, associated with the supine posture, also provides neuromodulatory signals to the brainstem and elicits cardiac sympathoinhibition. Here, we aimed to test the hypothesis that the sympathetically‐mediated heart rate response to muscle metaboreflex activation is blunted by cardiopulmonary loading in men. Nineteen healthy male subjects participated in the study (20 ± 2 years). Beat‐to‐beat blood pressure and heart rate were continuously measured by finger photoplethysmography (ML282B1‐X, AdInstruments). After a rest period a 90‐s static handgrip at 40% maximum voluntary contraction was performed followed by PEI. Trials were conducted with concurrent cardiopulmonary loading (supine posture) or unloading (seated posture). In a subset of subjects (n=5) trials were repeated after b‐1 adrenergic blockade (Atenolol 25 mg). At rest, the shift from supine to seated posture increased heart rate from 64±2 to 69±2 beats.min−1 (P<0.05), whereas blood pressure decreased from 90±2 to 84±2 mmHg (P<0.05). PEI provoked a robust increase in blood pressure from rest (Δ36±3 mmHg, P<0.05), which was not affected by body posture. During upright PEI, heart rate was elevated from rest (Δ10±2 beats.min−1, P<0.05), but blunted with cardiopulmonary loading (Δ2±2 beats.min−1, P>0.05 vs. rest). Following b‐1 adrenergic blockade, the heart rate response to upright PEI was significantly reduced (Δ5±3 beats.min−1, P<0.05), whereas the heart rate response to supine PEI was unaffected (Δ3±2 beats.min−1). In summary, the current study demonstrates that the heart rate response to isolated muscle metaboreflex activation is elevated by cardiopulmonary baroreceptor unloading due to a b‐1 adrenergic mechanism.Support or Funding InformationCAPES ‐ Coordination for the Improvement of Higher Education PersonnelCNPq ‐ National Council for Scientific and Technological Development