bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute strengthening of hypothalamic paraventricular nucleus GABAergic inhibition by glutamatergic input from the median preoptic nucleus is not observed in water deprived mice
Authors: Toney Glenn , Andrade Mary Ann , Yamaguchi Junya 
Published: May 2023

Our previous work in hypothalamic paraventricular nucleus (PVN) slice preparations showed that increasing ambient glutamate, either by bath application or local synaptic release, acutely strengthens GABAergic transmission by 20-30% through a mechanism dependent on glutamate uptake, likely by the neuronal transporter EAAT3 (EAAC1). Here, we first investigated the extent to which this homeostatic mechanism, termed glutamate-GABA strengthening or GGS, is recruited by glutamatergic inputs from the median preoptic nucleus (MnPO). Next, we investigated the impact of dehydration, which increases PVN glutamatergic input from the MnPO, on MnPO-driven PVN GGS. PVN neurons that received glutamatergic input from MnPO as well as GABAergic input from the surrounding peri-nuclear zone (PNZ) were identified in angled horizontal slices prepared from euhydrated (EUH) and 72 h water deprived (WD) male vGAT-ChR2 mice (C57Bl/6 BGND). Preliminary findings indicate that MnPO EPSCs evoked by 1 Hz electrical stimulation increased the amplitude of IPSCs (+22%) evoked by photo-stimulating ChR2-expressing GABAergic PNZ neurons every 15 s (n=4 cells). Recruitment of PVN GGS by glutamatergic MnPO inputs was absent in slices from WD mice (n=3 cells). Western blot of PVN whole-cell lysate from male C57Bl/6 WT mice revealed that EAAT3 expression was increased (+32%), not decreased, in the WD compared to EUH group (n=18 mice/group), raising the possibility that dehydration maximally recruits PVN GGS. Ongoing studies seek to confirm the later possibility and quantify the contribution of the GGS mechanism in PVN-driven sympathetic and hemodynamic responses to dehydration. Support: NS115072 and MH093320 (GMT) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mitochondrial Respiratory Function in Human Platelets: Influence of Sample Preparation, Assay Buffer and Instrumental Platform
Authors: Porter Craig , Treas Lillie , Pavliv Oleksandra , Bennuri Sirish , Sadler Daniel , Cotter Matthew , Rose Shannon , Børsheim Elisabet , Diaz Eva 
Published: May 2023

In humans, circulating blood cells such as platelets are being increasingly used as a readily available and minimally invasive biospecimen to determine mitochondrial respiratory function. Here, we set out to determine the influence of sample preparation, assay buffer composition, and instrumental platform, on the respiratory function of platelets isolated from human blood.Approximately 50 mL of whole blood was collected from healthy adults (n=16) following an overnight (>12 hr.) fast. Platelets were immediately isolated from whole blood by centrifugation. Respiratory function was assayed in intact and permeabilized platelets using an Oxygraph-2K (O2K) high-resolution respirometer (Oroboros Instruments). Respiratory function was assayed in intact platelets suspended in either culture (RPMI) or respiration (MIR05) media (both supplemented with 5 mM glucose, 1 mM pyruvate and 2 mM glutamine), or the participants own plasma. Respiratory function was also assayed in digitonin-permeabilized platelets suspended in both RPMI and MIR05. In addition, respiratory function was determined in intact platelets using a Seahorse Extra-Cellular Flux analyzer (XFe) in RPMI buffer containing 5 mM glucose, 1 mM pyruvate and 2 mM glutamine.In intact platelets assayed in suspension using an O2K, routine and ATP-linked respiration were 35 and 34% greater in cells assayed in RPMI compared to MIR05, respectively (P<0.001). However, coupling control in response to oligomycin was comparable in cells assayed in RPMI and MIR05 (92±4 vs. 94±4%). Compared to cells assayed in RPMI (0.19±0.01 pmol/s/100 million cells) or MIR05 (0.14±0.02 pmol/s/100 million cells), ATP-linked respiration was greater in intact cells assayed in their own plasma (0.24±0.02 pmol/s/100 million cells, both P<0.001). In digitonin-permeabilized platelets, ATP-linked respiration was greater when assayed in MIR05 compared to RPMI (0.36±0.08 vs. 0.30±0.07 pmol/s/100 million cells, P<0.05). Across instrumental platforms, routine and leak respiration were lower in intact platelets assayed on an O2K vs. XFe (P<0.05), whereas ATP-linked respiration was greater in cells assayed on an O2K. (P<0.001), due to a diminished coupling response to oligomycin in cells assayed in the XFe (P<0.001). Platelet respiratory function is influenced by sample preparation, assay buffer and protocol, and the instrumental platform used. Consideration of these factors is necessary when using platelet respiratory function as a readout of cellular energetics. Supported by USDA-ARS Project 6026-51000-012-06S, NIH 5P20GM109096-07 and 5R35GM142744-02. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
In vivo and ex vivo vascular function assessments in humans: Are they related?
Authors: Kofoed Jason , Tuncer Fatma , Kwok Alvin , Agarwal Jayant , Borrelli Marta , Iacovelli Jarred , Bisconti Angela , Richardson Russel , Broxterman Ryan 
Published: May 2023

Both in vivo and ex vivo vascular function assessments are commonly used approaches to better understand and examine vascular health. However, the degree to which such in vivo and ex vivo assessments relate to and, therefore, complement one another, especially in humans, is not well documented. Thus, the aim of the present study was to test the hypothesis that in vivo and ex vivo assessments of endothelial-dependent vasodilation would be strongly related to each other. Both in vivo (passive leg movement (PLM), brachial artery flow-mediated dilation (FMD), and reactive hyperemia to cuff-occlusion (RH)) and ex vivo (flow- and Acetylcholine (ACh)-induced vasodilation of branched sections of the deep inferior epigastric artery) were performed on a group of women (age: 49 ± 7 years; BMI: 28.7 ± 4.8 kg/m2) who underwent a deep inferior epigastric perforator (DIEP) procedure. There were positive, linear correlations between ACh-induced dilation and PLM-induced peak blood flow (r=0.81, p=0.188), PLM-induced total blood flow (r=0.82, p=0.176), FMD %dilation (r=0.99, p<0.01), FMD %dilation/shear (r=0.99, p=<0.01) and RH (r=0.21, p=0.797). Interestingly, there were no such relationships with ex vivo flow-induced vasodilation. Therefore, although this study provides evidence of strong relationships between vascular function assessed ex vivo and in vivo in humans, the current findings suggest that these relationships may be highly dependent upon the ex vivo methodology employed. This work was supported in part by Clinical Science Research and Development Career Development Award (IK2CX002114). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sympathetic pressor responses to glutamate nanoinjections in the rostral ventrolateral medulla are influenced by ovarian hormones in active but not sedentary female rats
Authors: George Grace , Blanzy Andrea , Carlson Laura , Brummelte Susanne , Mueller Patrick 
Published: May 2023

Cardiovascular disease (CVD) is the leading cause of death worldwide. One of the leading risk factors for CVD is hypertension. The incidence of hypertension in females increases drastically after the onset of menopause, suggesting female reproductive hormones have cardioprotective effects. However, the interaction between female reproductive hormones and blood pressure-lowering effects of regular physical activity are poorly understood. Blood pressure is controlled by a region of the brainstem known as the rostral ventrolateral medulla (RVLM). Previously, we reported that female rats had lower resting blood pressure than male rats, but had higher sympathoexcitatory responses to direct activation of the RVLM, as did sedentary animals from both sexes. Therefore, the purpose of our study was to examine the interaction between ovarian hormones and sedentary and active conditions. We hypothesized that during low or high hormone stages, sedentary female rats would have higher blood pressure responses to activation of the RVLM compared to the physically active female rats. In addition, we hypothesized that ovariectomy (OVX) would reduce the ability of exercise to blunt pressor responses to RVLM activation. OVX or sham surgeries were performed at four weeks of age and groups were split into active (running wheels) or sedentary conditions (no running wheels) for 12 weeks. At 16 weeks of age, vaginal lavages were collected under Isoflurane anesthesia to categorize stages of the estrous cycle and all rats received glutamate nanoinjections (1, 10, & 100 mM; 30 nl ea.) into the RVLM, under Inactin anesthesia. Sedentary versus active conditions promoted significantly greater pressor responses to nanoinjections of glutamate (100 mM) in the RVLM in both the high hormone (proestrus/estrus; 25±2 vs 14±3 mmHg, p<0.001) and low hormone (diestrus/metestrus; 21±2 vs 14±2 mmHg, p=0.007) groups. In OVX rats, the beneficial effects of exercise appeared to be lost as pressor responses to 100 mM of glutamate were similar in sedentary versus active rats (20±2 vs 25±6 mmHg, resp., p>0.05). Our results indicate that the absence of ovarian hormones offset the decreased pressor responses originating from the RVLM in active but not sedentary animals and could help explain the increased risk for CVD in females after menopause. They also demonstrate the increased risks of CVD and hypertension associated with a sedentary lifestyle as a result of this greater sensitivity to sympathoexcitation. 1R01-HL161233 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Acute and chronic effects of seizures on cardiorespiratory control in the SSKcnj16-/- rat
Authors: Eilbes Melissa , Manis Anna , Levchenko Vladislav , Forster Hubert , Palygin Oleg , Staruschenko Alexander , Hodges Matthew 
Published: May 2023

Epilepsy is a common neurological disorder in which 1/3rd of patients experience repeated seizures, putting them at greater risk for Sudden Unexpected Death in Epilepsy (SUDEP). A leading hypothesis based on human data suggests severe post-ictal cardiorespiratory suppression precedes a SUDEP event. However, the pathophysiological consequences of repeated seizures on cardiorespiratory control/function remain unclear. Our lab has previously established a rat model harboring an 18 bp-mutation in the Kcnj16 gene (encoding Kir5.1 channel; SSKcnj16-/- rats), which is susceptible to sound-induced (audiogenic) seizures. In this model, repeated seizures (1/day for 10 days) lead to ictal apnea, post-ictal respiratory suppression, blunted chemoreflexes, and spontaneous mortality. While the respiratory effects of repeated seizures in our rat model have been established, the cardiorespiratory sequence of events leading to a SUDEP-like event remain unknown. Here we test the hypothesis that repeated seizures in SSKcnj16-/- rats result in cardiorespiratory dysfunction and lead to a sequence of pathological events accompanying human SUDEP. Male and female SSKcnj16-/- rats (n=5,6) were surgically implanted with radiotelemetry pressure devices and allowed >3 days to recover. The rats were then housed in a custom-made plethysmograph for long-term housing to measure breathing, blood pressure (BP), heart rate (HR), and behavior continuously for 10 days (d). The rats were exposed to a sound stimulus (2 min) to elicit a seizure once/d for 10d. As reported previously, audiogenic seizures caused ictal apneas and transient post-ictal respiratory frequency depression. However, for the first time, we also found ictal asystole and dramatic decreases in HR but increases in BP for ~20 min after seizures. These acute effects of seizures on breathing and HR/BP appear to be exaggerated with increasing numbers of seizures throughout the 10d protocol. In addition, we captured during the 10d protocol SUDEP-like events in six out of eleven SSKcnj16-/- rats studied. Unlike most experiments that showed recovery of cardiorespiratory measures within ~30 min, SSKcnj16-/- rats with a terminal event had reduced ventilation due to a reduced tidal volume, and BP steadily declined with minimal effects on HR in the 2-5 hours preceding death (n=4). Our preliminary data suggest repeated seizures induce acute cardiorespiratory disruptions which in some cases can lead to a SUDEP-like event in SSKcnj16-/- rats characterized by suppressed tidal volume, hypopnea and time-dependent hypotension. Funded by NIH HL122358 (MRH), DK126720 (OP), and HL135749 (AS). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Retromer involvement in trafficking of the calcium-activated K channel, KCa3.1
Authors: Hamilton Kirk , Logue Matthew , Chueng Tanya , Pilmore Elliot , Devor Daniel , McDonald Fiona 
Published: May 2023

The intermediate-conductance Ca2+-activated K+ channel KCa3.1 ( KCNN4) regulates many physiological processes, including, water and electrolyte transport in polarised epithelia and vascular tone. Crucial for KCa3.1 function is the regulation of the number of channels at the plasma membrane. Even though, the mechanism of trafficking of KCa3.1 to and from the basolateral membrane (BLM) of epithelial cells has been advanced recently, there is opposing evidence suggesting that KCa3.1 is recycled back to the leading edge of migrating cells; while others have reported that KCa3.1 does not enter recycling endosomes, but is targeted for degradation. The highly conserved multi-protein complex Retromer has been demonstrated to regulate the membrane retrieval and recycling of many membrane-bound proteins, including ion channels. Using mass-spectrometry, it was reported that when VPS35, a core protein of the Retromer complex, was knocked-down, the membrane expression of KCa3.1 was reduced 1.4 fold in HeLa cells; suggesting a link between Retromer and trafficking of KCa3.1. In contrast, our data indicate KCa3.1 was not affected by knockdown of VPS35 in our FRT (Fischer rat thyroid)-KCa3.1 stable cell line. Here, we have examined other key components (sorting nexins SNX1, SNX4, SNX27; cargo binding proteins) of the Retromer complex to determine if those proteins aid in trafficking of KCa3.1 directly to the BLM. We conducted immunoblot and Ussing chamber experiments to examine the effects of knockdown of SNX 1, SNX2 or SNX27 on the BLM population of KCa3.1 and functional expression of the channel (K+current), respectively. Using our FRT-KCa3.1 cell line, we demonstrate knockdown of SNX1, SNX4 or SNX27 decreases KCa3.1 current. Further, we demonstrate knockdown of SNX4 or SNX27 decreases BLM expression of KCa3.1, consistent with the decrease in current observed.These data, along with our previous data, strongly indicate that the role of Retromer in the trafficking of KCa3.1 to the BLM of epithelial cells is quite dynamic. Reducing SNX4 or SNX27 have notable effects on trafficking of KCa3.1. While knockdown of SNX1 might affect the trafficking of KCa3.1 by altering other proteins of the Retromer complex. This work was supported by the National Institutes of Health grants HL083060 and HL092157 to DCD, Lottery Health New Zealand (R-LHR-2019-101706) to FJM, Aim Fund grant to KLH, and the Department of Physiology, University of Otago. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
O-Mannosylation of alpha-dystroglycan is required to prevent stress-induced cardiac muscle fiber damage and heart failure
Authors: Hord Jeffrey , Anderson Mary , Prouty Sally , Melton Shelly , Weiss Robert , Campell Kevin 
Published: May 2023

Mutations in glycosyltransferases involved in the O-mannosyl processing and formation of matriglycan on alpha-dystroglycan (αDG) constitute a subset of limb girdle muscular dystrophies referred to as dystroglycanopathies. Patients exhibit a range of cardiac phenotypes, including progressive disease leading to heart failure and acute events that can result in death. The goal of the present study was to investigate the factors that provoke heart pathology in a mouse model of dystroglycanopathy. We disrupted O-mannosylation of αDG in vivo by designing a striated muscle-specific protein O-mannosyltransferase 1 knockout mouse line. Hearts from conditional knockout mice appeared histologically and functionally similar to littermate controls up to 60-weeks-of-age. Acute pharmacological-induced contractile stress resulted in large patches of damaged cardiomyofibers and was associated with bradycardia, as determined by electrocardiography, in knockout mice twenty-four hours following the stressor. In hearts from littermate control mice, stress-induced cardiac muscle damage was limited to small patches or individual fibers and did not cause cardiac dysfunction. The contraction-induced cardiac muscle fiber damage observed in the knockout mice led to aberrant remodeling that developed into extensive ventricular fibrosis when examined twenty-eight days later, an effect that was not observed in control hearts. These data indicate that cardiomyopathy due to improper glycosylation of αDG can be instigated by a short-lived increase in workload. Cardiovascular Institutional Research Fellowship -- National Institutes of Health (5T32HL007121-45); Paul D. Wellstone Muscular Dystrophy Specialized Research Center (1U54NS053672); Howard Hughes Medical Institute This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Chronic intermittent hypoxia induces remodeling of sympathetic innervation in mouse heart (atria and ventricles)
Authors: Bizanti Ariege , Zhang Yuanyuan , Toledo Zulema , Bendowski Kohlton , Chen Jin , Cheng Zixi 
Published: May 2023

Chronic intermittent hypoxia (CIH) is a commonly used model for sleep apnea, which constitutes a major risk factor for many cardiovascular diseases (CVD). Autonomic imbalance (sympathetic overactivity and parasympathetic withdrawal) is hypothesized to be a causal contributor of CIH-induced CVD. Previously, we showed that CIH reduced baroreflex control of heart rate and induced vagal cardiac motor neuronal death in the brainstem. CIH activates the central nervous system circuitry, which in turn enhances sympathetic outflow. However, whether CIH induces remodeling of the peripheral cardiac sympathetic innervation remains undetermined. Here, C57BL/6J male mice (2 months, n=7/group) were exposed to room air (RA, 21% O2) or CIH (alternating 21% and 5.7% O2, every 6 minutes, 10hr/day) for 8-10 weeks. Flat-mounts of their whole left and right atria, ventricles, and interventricular septum were prepared and immunohistochemically labeled for tyrosine hydroxylase (TH, a sympathetic postganglionic marker). Using confocal microscopy (or Zeiss M2 Imager) and a Neurolucida Digitization and Tracing system, we scanned and quantitively analyzed the sympathetic axon density in both the RA and CIH experimental groups. We found: 1) Several large TH-IR bundles entered the atria and ventricles and branched out into smaller bundles and eventually ramified into individual axons and their terminals that covered the entire atria, ventricles, and interventricular septum. 2) TH-IR neurons were observed in the intrinsic cardiac ganglia (ICG). Most TH-IR axons passed through the ICG and innervated the cardiac muscles, blood vessels, and fat cells. 3) CIH significantly remodeled the TH-IR axon innervation of the atria. Specifically, CIH significantly increased the density of TH-IR innervation at the sinoatrial (SA) node, the atrioventricular (AV) node, and the auricles (p <0.05, n=7). 4) CIH-induced TH-IR axon innervation structural remodeling (increased density and complexity) in the ventricles and interventricular septum. 5) TH-IR axon innervation will be integrated into 3D heart scaffold to provide a common coordinate framework for RA and CIH comparison. These results suggest that increased sympathetic innervation may further amplify the effects of enhanced CIH-induced central sympathetic drive to the heart. Along with our previous finding that CIH reduces parasympathetic control of the heart, our work supports the hypothesis that chronic autonomic imbalance underlies CIH-induced CVD. This study was supported by NIH HEAL/SPARC U01 NS113867-01, NIH R15 R15HL137143-01A1, and UCF dissertation completion Fellowship. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.