bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral autoregulation in fulminant hepatic failure (1068.10)
Authors: Nogueira Ricardo , Mendes Fernando , Pacheco Marcelo , Lins Karla , Teixeira Manoel , Bor‐Seng‐Shu Edson
Published: June 2021

Objective: The aim of this study is to evaluate hemodynamic and cerebrovascular autoregulation capacity in patients with fulminant hepatic failure (FHF) before and after liver transplantation.

Material and Methods: Twenty five patients with FHF diagnosis were evaluated. Cerebral hemodynamic was evaluated by cerebral blood flow velocity in the middle cerebral arteries, using transcranial Doppler device equipped with 2 MHz probe. CA assessment was carried out through static autoregulation index (SARI) which studies the effects of increases in mean arterial blood pressure (MAP) on cerebral blood flow velocity. MAP was increased pharmacologically up to a maximum limit of 120 mmHg.

Results: From 25 patients with FHF diagnoses, 17 were evaluated before and after liver transplantation. Twenty one patients (84%) had pre transplantation impaired CMA. Ten of 17 patients recovered CMA in 48 hours following LTx.

Conclusion: Our findings showed impaired CMA in most patients with FHF. For the majority of patients who underwent LTx, CMA was restored 48 hours after transplantation.
Blunted cerebrovascular response to exogenous nitric oxide in POTS (1068.12)
Authors: Del Pozzi Andrew , Medow Marvin , Stewart Julian
Published: June 2021

Cognitive deficits are characteristic of postural tachycardia syndrome (POTS). Intact nitrergic nitric oxide (NO) is important to cerebral blood flow (CBF) regulation, to neurovascular coupling, and to cognitive efficacy. POTS patients often experience defective (NO) mediated vasodilation caused by oxidative stress. We used combined transcranial Doppler ultrasound, to measure CBF velocity (CBFv), and near‐infrared spectroscopy (NIRS), to measure cerebral oximetry while supine. We previously showed dilation of the middle cerebral artery (MCA) in response to a bolus administration of the NO donor sodium nitroprusside (SNP) in healthy volunteers. We hypothesized a blunted MCA response to SNP in POTS. The SNP responses of 17 POTS patients were compared with 12 healthy controls (ages 14‐28). CBFv in POTS and control were not different at baseline (75 ± 3 vs. 71 ±2 cm • s‐1 P = 0.31) and decreased to a lesser degree with SNP in POTS (to 71 ± 3 vs 62 ± 2 cm • s‐1; P = 0.02). The changes in total and oxygenated hemoglobin (8.83 ± 0.45 and 8.13 ± 0.48 µmol/kg tissue) were markedly reduced in POTS compared to control (14.2 ± 1.4 and 13.6 ± 1.6 µmol/kg tissue), primarily due to increased venous efflux. The data indicate reduced cerebral oxygenation, blunting of cerebral arterial vasodilation and heightened cerebral venodilation in response to exogenous NO.

Grant Funding Source: NHLBI
tPA‐S481A prevents impairment of cerebrovascular autoregulation by endogenous tPA after traumatic brain injury by upregulating p38 MAPK and inhibiting ET‐1 (1068.13)
Authors: Armstead William , Bohman Leif‐Erik , Riley John , Yarovoi Serge , Higazi Abd Al‐Roof , Cines Douglas
Published: June 2021

Traumatic brain injury (TBI) causes loss of cerebrovascular autoregulation. Mitogen activated protein kinase (MAPK) isoforms ERK and JNK and ET‐1 are mediators of impaired cerebral hemodynamics after TBI. Excessive tPA released after TBI may impair autoregulation either by over‐activating NMDA receptors (NMDA‐Rs) or by predisposing to intracranial hemorrhage. Our work shows that a catalytically inactive tPA variant (tPA‐S481A) that competes with wild type (wt) tPA for binding to NMDA‐R through its receptor docking site but that cannot activate it, prevents activation of ERK by wt tPA and impairment of autoregulation when administered 30 min after FPI. We investigated the ability of variants that lack proteolytic activity but bind/block activation of NMDA‐Rs by wt tPA (tPA‐S481A), don’t bind/block activation of NMDA‐Rs but are proteolytic (tPA‐A296‐299), or neither bind/block NMDA‐Rs nor are proteolytic (tPA‐A296‐299S481A) to prevent impairment of autoregulation after TBI and the role of MAPK and ET‐1 in such effects. Fluid percussion brain injury was induced in anesthetized pigs equipped with a closed cranial window. Results show that tPA‐S481A given 3h post TBI, but not tPA‐A296‐299 or tPA‐A29‐299S481A prevents impaired autoregulation by upregulating p38 and inhibiting ET‐1. These data suggest that tPA‐S481A has a realistic therapeutic window and focuses intervention on NMDA‐Rs to improve outcome.

Grant Funding Source: Supported by HD 57355
Post‐traumatic stress disorder does not affect cerebrovascular reactivity (1068.18)
Authors: Stojanovic‐Radic Jelena , Reyes Levy , Ghobreal Bemin , Blatt Melissa , Acosta Amanda , Chandler Helena , Serrador Jorge
Published: June 2021

Post‐traumatic stress disorder (PTSD) is a chronic psychiatric disorder, with symptoms of hyperarousal, which can alter the biological stress response. Our objective was to determine whether possible increased sympathetic tone in veterans with PTSD affected cerebrovascular function due to altered autonomic control. To assess this we measured sympathetic activity from low frequency blood pressure (BP) and heart rate (HR) variability and cerebrovascular function during hyper/hypocapnia using transcranial Doppler in 29 Veterans (10 with PTSD). There was no difference in BP or cerebral flow velocity in the middle (MCA: 51±5 vs 53±3 cm/s) or anterior cerebral artery (ACA: 48±7 vs 49±3 cm/s). Examination of autonomic indicators found no difference in low frequency power in HR or BP variance. Similarly PTSD status did not affect cerebrovascular reactivity for either the MCA (2.2±0.1 vs 2.2±0.1 %/mmHg) or ACA (2.0±0.2 vs 2.3±0.2 %/mmHg). Surprisingly, regardless of PTSD status, all veterans had a blunted response to hypercapnia (MCA: 1.3±0.2; ACA: 1.3±0.2 %/mmHg) compared to hypocapnia (MCA: 2.8±0.2; ACA: 2.7±0.2 %/mmHg). In contrast to our hypothesis, we did not find increased sympathetic activity in PTSD or impaired cerebral blood flow regulation. One explanation for this finding is that our PTSD sample was not of the hyperarousal type. Since we anticipate that hyperarousal is associated with increased sympathetic outflow, if our subjects mainly had dissociative type PTSD, there could be no difference in autonomic function. The finding of impaired vasodilation to CO2 but not vasoconstriction in all Veterans may indicate impaired cerebral vascular function.

Grant Funding Source: Supported by NIH R21DC009900 (Serrador) as well as the WRIISC and the Office of VA Public Health
Sudden onset of hearing loss after cerebral ischemia (1068.3)
Authors: Kamat Pardip , Kalani Anuradha , Tyagi Suresh , Tyagi Neetu
Published: June 2021

Although clinical reports suggest hearing loss in stroke patients but the mechanism is still unclear. Synapse, connexin and sodium epithelial channel proteins involved in processing of sound from auditory cortex to cochlea. Therefore, we hypothesize that hearing loss after cerebral ischemia is associated with alteration in synapse, gap junctions and sodium epithelial channel (ENaC) proteins. To test this hypothesis, we employed male wild type mice; 1) Sham, 2) WT+ ischemia reperfusion (I/R). Ischemia was performed for 60 min and reperfusion for 24 h. The infarct area was measured using 2,3,5‐triphenyltetrazolium chloride staining. Permeability was determined by Evans blue extravasation. In order to accomplish the proposed objectives, we performed physiological, behavior, molecular and immunohistochemistry approaches. The hearing thresholds were determined by recording the auditory brainstem response. We found that brain edema, infarct size and Evans blue leakage were increased in I/R as compared to sham‐operated group. Caspase‐3,‐9 and TUNEL positive cells were increased in ischemic cortex as compared to non‐ischemic cortex, indicates apoptosis and neuronal damage. Moreover, increased expressions of MMPs (MMP‐2,‐9,‐13), IL‐6 and decreased expressions of tight junction proteins in I/R group as compared to control group, signifies inflammation and blood brain barrier (BBB) disruption. We also observed decrease levels of PSD95, SAP97, Cx‐43, ENaCβ, ENaCγ and increase expression of Cx‐45, whereas no change was observed in Cx‐26 in I/R as compared to sham‐operated group. Reduced auditory response confirmed by sound pressure level (SPL) indicates hearing loss. These data suggest that hearing loss in I/R mice was primarily due to alteration in connexin, synapse and ENaC channels.

Grant Funding Source: HL107640
Regional cerebral blood flow responses to rapid reductions in blood pressure after high level spinal cord injury: the effect of alpha1‐agonist (1068.8)
Authors: Phillips Aaron , Krassioukov Andrei , Ainslie Philip , Warburton Darren
Published: June 2021

Spinal cord injury (SCI) above the T6 level frequently results in orthostatic intolerance, but how cerebral blood flow (CBF) responds to an orthostatic challenge in SCI is poorly understood. It is also unclear how alpha1 agonists, meant to improve orthostatic tolerance, influence the CBF response. This study examined: 1) the acute regional CBF velocity (CBFv) response to acute blood pressure (BP) reductions secondary to orthostatic stress in SCI, compared to able‐bodied controls (AB), and 2) the effect of Midodrine (alpha1‐agonist) on orthostatic tolerance and CBFv regulation in SCI. Ten individuals with SCI >T6, and 10 age‐and sex‐matched controls had beat‐by‐beat BP, as well as middle and posterior cerebral artery blood velocity (MCAv, PCAv) recorded during a progressive tilt‐test to quantify the acute CBF response and orthostatic tolerance. Dynamic CBFv‐BP relationships were evaluated from the first 60s after tilt. The SCI group was tested again after administration of an alpha1‐agonist (10 mg midodrine) in order to elevate BP. The acute (i.e., 0‐30s after tilt) MCAv and PCAv responses were similar in SCI and AB. In contrast, Midodrine led to improved PCAv responses 30‐60 s (10±3 vs. 4±2 %decline; p<0.05) after tilt, and a 59% improvement in orthostatic tolerance (p<0.01). The vertebrobasilar region may be particularly susceptible to hypoperfusion in SCI, leading to increased orthostatic intolerance.

Grant Funding Source: Supported by HSFC, NSERC, MSFHR & CNF
Reduced cerebral autoregulation as the genesis of symptoms in orthostatic intolerance in elderly (1069.3)
Authors: Sanders Marit , Meel ‐ van den Abeelen Aisha , Slump Cornelis , Lagro Joep , Claassen Jurgen
Published: June 2021

Background: The prevalence of orthostatic hypotension (OH) increases with age and affects over 50% of elderly visiting a falls and syncope outpatient clinic. OH may be symptomatic or asymptomatic. Surprisingly little is known why serious symptoms as dizziness, falling and syncope occur. A possible cause of symptom development may be cerebral hypoperfusion due to loss of cerebral autoregulation (CA). The purpose of this study is to compare CA in elderly with symptomatic and asymptomatic OH and a control group without OH.

Methods: Dynamic CA is assessed in 20 elderly with symptomatic OH, 20 with asymptomatic OH and 20 age‐matched healthy subjects without OH using transfer function analysis (TFA) on blood pressure (BP) and cerebral blood flow velocity (CBFV). Single supine to standing measurements is used to assess time domain changes in BP, CBFV and heart rate. Patient inclusion continues until March 2014.

Results: TFA provides outputs gain and phase of the relation between BP and CBFV to assess CA. Time domain analyses will be used to report time to peak and nadir, and time and amount of recovery.

Conclusions : This study characterizes CA in symptomatic and asymptomatic OH. The yet preliminary conclusion is that a reduced CA performance is related to the subject group with symptomatic OH in comparison to the asymptomatic OH group.
Nebivolol reduces intracellular Ca2+ and elicits dilations in isolated rat basilar arteries (1070.7)
Authors: Cseplo Peter , Vamos Zoltan , Batai Istvan , Torok Orsolya , Springo Zsolt , Toth Attila , Koller Akos
Published: June 2021

Experimental and clinical studies have revealed that the antiarrhythmic and antihypertensive, highly selective β1‐adrenerg receptor blocker, nebivolol elicits dilations in peripheral arteries, in which a role for nitric oxide (NO) has been implicated. However, its effect on the diameter of cerebral vessels has not been investigated. We hypothesized that nebivolol increases the diameter of isolated cerebral arteries.

Basilar arteries (BA) were isolated from male Wistar rats and were mounted into isotonic myograph chamber. Diameters of vessels were measured by video‐microscopy in response to vasoactive agents, and the intravascular Ca2+ changes was detected by the fura‐2 ratiometric method.

Nebivolol elicited significant vasodilation, despite the presence of L‐NAME (NOS inhibitor) or ODQ (guanylate cyclase blocker) or SQ22536 (adenylyl cyclase blocker). Nebivolol significantly reduced the ratiometric calcium‐signal that correlated with changes in diameter.

In isolated BA nebivolol: 1) elicits significant dilation, 2) to which NO‐cGMP/cAMP pathway does not contribute significantly, 3) decreases vascular wall [Ca2+]i. (Supported by: OTKA K108444, SROP‐4.2.2.A‐11/1/KONV‐2012‐0024, SROP‐4.2.2.A‐11/1/KONV‐2012‐0017, TAMOP 4.2.4.A/2‐11‐1‐2012‐0001 “National Excellence Program”)

Grant Funding Source: OTKA K108444, TAMOP 4.2.4.A/2‐11‐1‐2012‐0001 „National Excellence Program”
Time course of coronary vasodilator response to intravenous adenosine in humans (1071.2)
Authors: Gao Zhaohui , Monahan Kevin , Brandt Kristen , Blaha Cheryl , Herr Michael , Sinoway Lawrence
Published: June 2021

Measurement of coronary flow velocity reserve (CFVR) has proven useful in assessing coronary vasodilator potential in humans. CFVR is frequently assessed by measuring coronary vasodilator responses to intravenous infusion of adenosine. Importantly, the time course of the coronary vasodilator response to intravenous adenosine infusion has not been well documented. We retrospectively studied this time course during 39 adenosine stress tests obtained in 21 adults (6 F; age range 22‐76 yrs.). Peak coronary blood velocity (CBV) in the left anterior descending artery was assessed non‐invasively in the distal left anterior descending artery using transthoracic Doppler echocardiography before (baseline) and continuously throughout a 6‐min adenosine infusion (0.14 mg/kg/min) in all subjects. CFVR was quantified as CBV peak adenosine/CBVbaseline. Overall, adenosine infusion increased CBV in all subjects (P<0.001) and peak CFVR was observed during the 4th minute in the group as a whole. However, marked variability in the timing of this response was observed. On an individual basis peak CFVR occurred during the 2nd (n=11), 3rd, (n=9), 4th (n=9,) 5th (n=7) and 6th min (n=3) of adenosine infusion. These data suggest that maximal coronary vasodilator responsiveness (i.e., CFVR) occurs variably between the 2nd and 6th minute of adenosine infusion. Based on these findings, we believe the current 6 min adenosine infusion protocol is appropriate. However, we suggest that CBV be monitored during each minute of the infusion so as to capture the true peak response in all subjects.

Grant Funding Source: Supported by P01 HL096570 and UL1 TR000127
Coronary perivascular adipose tissue and K+ channel‐mediated vasodilation in lean and obese hearts (1071.4)
Authors: Noblet Jillian , Owen Meredith , Goodwill Adam , Dick Gregory , Tune Johnathan
Published: June 2021

This investigation examined the mechanisms by which perivascular adipose tissue (PVAT) influences coronary vasodilation. Coronary arteries from lean and obese Ossabaw swine were isolated, incubated with or without 0.3 g of PVAT for 30 min and pre‐constricted with U46619 (1 μM). In arteries cleaned of PVAT, vasodilation to adenosine (0.01‐30 μM) was decreased ~25% in obese arteries. However, the presence of PVAT attenuated adenosine relaxation ~30% in both lean and obese arteries. Pre‐constriction with KCl (60 mM) abolished coronary dilation to adenosine, suggesting activation of K+ channels. Inhibition of KCa channels with penitrem A (1 μM) impaired responses to adenosine in lean (p<0.001), but not obese (p=0.53), arteries. Dilation to the KCa channel agonist NS‐1619 (30 μM) was attenuated by PVAT in lean, but not obese, arteries. Inhibition of KV7 channels with linopirdine (10 μM) impaired adenosine dilation ~56% in lean arteries. Relaxation to the KV7 channel agonist L364,373 (10 μM) averaged 91 ± 5% in lean arteries vs. 55 ± 8% in obese arteries. Incubation with PVAT diminished vasodilation to L364,373 by ~22% in lean arteries, but had no effect in obese arteries. These findings indicate that while PVAT attenuates adenosine‐mediated vasodilation to a similar extent in lean and obese hearts, the contribution of KCa and KV7 channels to coronary vasodilator responses is markedly impaired in the setting of obesity.

Grant Funding Source: Supported by HL117620 and HL092245
Sodium butyrate remodels whole genome nucleosome maps and attenuates high fat diet‐induced mitochondrial dysfunction in skeletal muscle from C57BL6/J mice (1072.1)
Authors: Henagan Tara , Navard Alexandra , Ye Jianping
Published: June 2021

High fat diets (HFDs) largely contribute to the onset and progression of obesity and type 2 diabetes and are used to generate models of diet‐induced obesity and insulin resistance; yet, the epigenetic mechanisms underlying the effects of HFDs are not fully understood. Here, we determined whole genome differences in nucleosome occupancy or positioning in skeletal muscle from C57BL6/J mice fed either a 10% low fat diet (LFD), 60% HFD or 60% HFD plus sodium butyrate (NaB) for 9wks using microccocal nuclease digestion followed by high throughput sequencing (MNase‐seq). Additionally, metabolomics of 45 various acylcarnitine species and ratios and immunohistochemistry for fiber typing were performed in the quadriceps muscle. We show that NaB supplementation prevents HFD‐induced obesity and insulin resistance and that diet‐induced changes in nucleosome occupancy and positioning are associated with parallel increases in muscle mitochondrial function and type 1 oxidative fiber content. Targeted analysis of peroxisome proliferator‐activated receptor gamma coactivator 1 alpha (Pgc1α), also suggests that ‐1 nucleosome positioning within the Pgc1α promoter may be important in diet‐induced mitochondrial adaptation. These data provide additional identified genomic loci that may be epigenetically regulated by diet to determine skeletal muscle mitochondrial adaptation.

Grant Funding Source: Supported by NIH NIDDK 5T32‐DK064584‐09 (TMH), NIH COBRE 8P20‐GM103528‐07 and NORC 5P30‐DK072476‐07
Endothelial peNOS signaling and ET‐1 mRNA expression during acute hyperinsulinemia in type 2 diabetes (1072.5)
Authors: Boyle Leryn , Padilla Jaume , Credeur Daniel , Fadel Paul , Thyfault John
Published: June 2021

Increased endothelin‐1 (ET‐1) and reduced endothelial nitric oxide production are thought to play a role in vascular dysfunction in type 2 diabetes (T2D). However, little is known in humans about changes in endothelial signaling in response to insulin stimulation. Therefore, endothelial nitric oxide synthase (eNOS) signaling and ET‐1 expression were measured from vastus lateralis skeletal muscle biopsies taken before and 60 min into a hyperinsulinemic euglycemic clamp in 6 healthy controls (body fat: 22.8±3.6 %, glucose disposal rate (GDR): 12.6±2.4 mg/kg lean body mass (LBM)/min) and 5 T2D (body fat: 43.4±4.6%, GDR: 6.7±2.5mg/kg LBM/min). Muscle samples were analyzed for pAKT (ser473), AKT, peNOS (ser1177) and eNOS protein and ET‐1 mRNA expression. In response to insulin, peNOS/eNOS was not significantly different between groups (controls: 1.13±0.22, T2D: 0.69±0.31 fold change from baseline; p>0.05). The increase in ET‐1 mRNA from baseline (controls: 1.0±0.4, T2D: 3.4±1.4, p>0.05) was also not different during insulin stimulation (controls: 1.3±0.7, T2D: 2.1±0.9, p>0.05). However, the fold increase of pAKT/AKT to hyperinsulinemia was significantly different between groups (controls: 3.1±0.4, T2D: 1.8±0.4, p=0.002). These initial findings suggest that insulin‐mediated phosphorylation of eNOS protein and induction of ET‐1 mRNA are not significantly different between healthy and T2D individuals.

Grant Funding Source: Supported by AHA 12PRE12080242(LJB)
Glucose stimulated adipose tissue blood flow is reduced after high fat feeding despite diminished resistance artery vasoconstrictor reactivity (1072.9)
Authors: Henson Grant , Reihl Kelly , Donato Anthony , Behnke Brad , Lesniewski Lisa
Published: June 2021

Fasted adipose tissue blood flow (ATBF) supplies energy via transport of stored free fatty acids, whereas after feeding ATBF increases to reduce circulating free fatty acids. Although high fat diet (HF; 40% Kcal fat) has been demonstrated to reduce endothelium dependent dilation in epididymal white adipose tissue (eWAT) resistance arteries, the effect of HF on eWAT artery vasoconstrictor reactivity is unknown. Here, we examined basal and glucose stimulated (2 g/kg, ip, 15 min) ATBF using radiolabelled microspheres as well as vasoconstrictor responses in eWAT resistance arteries in young normal chow (NC: 14% Kcal fat) and HF fed male B6D2F1 mice. Basal ATBF (eWAT) was not different in HF (0.20 ± 0.1 v 0.08 ± 0.02 %Cardiac Output, p > 0.05) compared to NC mice. Glucose stimulation increased ATBF 5‐fold in NC (p = 0.03) but this increase was blunted in HF mice (1.6‐fold, P=0.09). Although KCl‐induced eWAT vasoconstriction did not differ between diet groups, HF blunted maximal vasoconstriction to norepinephrine (26%), angiotensin‐II (35%), and endothelin‐1 (11%) compared with NC (All p < 0.05). In the face of diminished endothelium dependent dilation and reduced nitric oxide, reductions in vasoconstrictor reactivity may preserve basal ATBF in HF mice. However, enhanced vasoconstriction does not play a role in the diminished hyperemic response to glucose in adipose tissue after HF.
Cardiac volume regulation: transition among two phenotypes in heart failure (1073.2)
Authors: Kerkhof Peter , Li John , Kresh J , Heyndrickx Guy
Published: June 2021

Background. Guidelines for heart failure (HF) with preserved ejection fraction (pEF) dictate that left ventricular (LV) end‐diastolic pressure > 16 mmHg, EF > 50% and end‐diastolic volume index (EDVI) < 97 mL/m2. Only half of HF patients (pts) present with a classical pattern of reduced EF (rEF). Prevalence of transition from HFpEF to HFrEF reportedly constitutes (either way) as much as 39%. The volume regulation graph (VRG) is explored to theoretically elucidate this occurrence.

Methods. LV EDVI and end‐systolic volume index (ESVI) by angiography are analyzed in 48 pts receiving betablockers, with HFpEF (n=35) and HFrEF (n=13) subgroups. Regression analysis for ESVI to EDVI yields VRG. The 2SE ranges and 98% CI limits show potential transition to the complementary territory.

Results. For pEF: ESVI = 0.31 EDVI ‐ 2.55, r=0.51 and for rEF: ESVI = 0.66 EDVI ‐ 5.45, r=0.95. The 2SE zones show overlap, suggesting occurrence of transition, especially for 50 < ESVI < 100 mL/m2. An additional group of 44 pts with follow‐up (ranging from 27 to 2385 days) reveals that over time ESVI may decrease by 50% or increase by up to 250%, thus demonstrating LV volumetric plasticity. Notably, about 25% of HFpEF pts can transit to HFrEF territory with a 10% increase in ESVI, while some 40% would convert to HFpEF with a 10% reduction in ESVI.

Conclusions. The VRG explains considerable transition from HFrEF to HFpEF and v.v., requiring only a 10% change of ESVI, or roughly a 10% alteration in EF. The novel VRG construct confirms observations from other longitudinal studies.
Respiratory loading causes right‐to‐left shunting through the PFO (1073.5)
Authors: Moses Kayla , Bates Melissa , Farrell Emily , Lamers Luke , Baus Fiona , Pegelow David , Eldridge Marlowe
Published: June 2021

Recruitment of the patent foramen ovale (PFO) while SCUBA diving has conventionally been thought to be caused by Valsalva maneuvers performed during ascent and may provide a route for venous air emboli to enter the arterial circulation. Alternatively, we hypothesized that mild increases in inspiratory and expiratory load, similar to that provided by a SCUBA regulator, would be sufficient to recruit the PFO. Two healthy adults with a PFO completed three randomized trials (inspiratory, expiratory, and combined (inspiratory/expiratory) loading) consisting of 6 levels of incrementally increasing load, to a maximum resistive load of 20 cmH2O/L/s. A saline contrast echocardiogram was performed at each resistive load to determine foramen ovale patency. Right atrial and pulmonary wedge pressures were obtained using a Swan Ganz catheter, and intrathoracic pressure was estimated using an esophageal balloon catheter. We found that PFO recruitment occurred in response to both inspiratory and expiratory loads. We will further examine the relationship between PFO recruitment, phase of the respiratory cycle, and the right‐to‐left atrial pressure difference during both loading conditions.
Enzyme‐linked immunosorbent assay is a viable method for determining release kinetics of cardiac myosin binding protein‐C following isoproterenol‐induced cardiac injury (1073.8)
Authors: Jagadeesan Aravindakshan , Barefield David , Govindan Suresh , Kuster Diederik , Sadayappan Sakthivel
Published: June 2021

Cardiac myosin binding protein‐C (cMyBP‐C) is shown to be released into the bloodstream following myocardial infarction (MI), suggesting its potential as a biomarker post‐MI. To explore this further, dose‐ and time‐dependent effects on cMyBP‐C release into circulation can be determined following isoproterenol (ISO) administration, an established model of drug‐induced cardiac injury in mice. The objective is to establish a quantitative enzyme‐linked immunosorbent assay (ELISA) that is specific and sensitive in measuring concentrations of cMyBP‐C in serum samples. To determine cMyBP‐C in serum samples following ISO‐induced injury, sandwich ELISA was developed using monoclonal and polyclonal antibodies against cMyBP‐C. To generate a standard graph, cMyBP‐C N’ recombinant peptide (40 kDa) was used to determine inter‐ and intra‐plate coefficient of variability (CV,%), as well as the respective recovery (%) values. The sandwich ELISA assay for quantifying serum concentrations of cMyBP‐C was established with an average lower limit of detection of 0.36 ng/ml and upper limit of detection up to 2000 ng/ml, indicating the assay can detect cMyBP‐C within the working range of our experiment. Furthermore, an inter‐ and intra‐plate variability of 4.7% and 4.2%, respectively, suggests a reproducible assay. The average inter‐ and intra‐plate recoveries were, 101% and 103%, illustrating the accuracy of the assay in measuring cMyBP‐C concentration. Using this assay, future experiments will be conducted to measure the exact amount of cMyBP‐C in the mice serum post‐cardiac injury.

Grant Funding Source: American Physiological Society ‐ Undergraduate Summer Research Fellowship
Effect of low birth weight on inflammation biomarkers and autonomic function in healthy young adults (1074.4)
Authors: Bao Sarina , Sasaki Konosuke , Sato Haruka , Kanno Emi , Maruyama Ryoko
Published: June 2021

A number of epidemiological studies have reported an association between birth weight (BW) and hypertension in adulthood. Low‐grade inflammation and deterioration of autonomic regulation play an important role in hypertension. However, the association with BW is unclear, and few relevant studies have been performed in healthy young adults. We examined the association of BW and hypertension risks in a high‐risk Mongolian population. We performed electrocardiography in 20 Mongolian subjects aged 23‐34 years and investigated blood pressure (BP) and heart rate variability at rest and during postural change from a supine to a sitting position. Leukocyte count, platelet count, total cholesterol, HDL‐C, LDL‐C, triglycerides and high‐sensitivity C‐reactive protein (Hs‐CRP) were measured. BW was inversely related to both leukocyte (r = ‐0.49) and platelet counts (r = ‐0.49). BMI was positively related to systolic BP (SBP; r = 0.58), LF/HF (r = 0.47), the atherosclerotic index (r = 0.53) and Hs‐CRP (r = 0.55). Following postural change, the normal BW group (2,500 g 蠄 BW < 4,000 g) showed a significant increase in heart rate, SBP, and LF/HF, whereas the low BW (BW < 2,500 g) and high BW groups (BW 蠅 4,000 g) showed no significant responses. These results suggest that low BW may be an essential predictor of an increase in low‐grade inflammation and deteriorating of autonomic regulation in Mongolian healthy adults.
Comparative assay of oxidative stress biomarkers on normotensive and hypertensive, pre‐menopausal and postmenopausal women: a pilot study (1074.8)
Authors: Calzada‐Frías Jesús , Lugo‐Martínez Gabriela , Jiménez‐Zamarripa Carlos , Ocharán‐Hernandez María , Cariño‐Cortés Raquel , Calzada‐Mendoza Claudia
Published: June 2021

Introduction: Menopause is defined as the cessation of menstruation for one year in raw, due to ovarian dysfunction, which decreases the production of estrogen. During this stage, several pathologies can be developed, such as hypertension which is associated to oxidative stress, then, there are two risk factors to participate on cardiovascular diseases.

Currently, knowledge of factor present in postmenopause in relationship to cardiovascular diseases can help to propose therapeutic guides to reduce them.

Objective: To analyze the association between oxidative stress on pre‐menopausal and postmenopausal women with hypertension.

Methods: In the present study were included fifty six divided in four groups: a) normotensive‐premenopausal, b) hypertensive‐premenopausal, c) normotensive‐postmenopausal and d) hypertensive‐postmenopausal. Menopause was corroborated by clinical evaluation. On the other hand, oxidative stress biomarkers analyzed, were a) malondyaldehyde (MDA) for lipid oxidation, carbonyl group for protein oxidation and antioxidant defense was evaluated by determination of carbonyl and sulfhydryl group, respectively; anthropometric evaluation was evaluated too.

Results: Women included were classified according to their status (normotensive or hypertensive, pre‐menopausal or postmenopausal) which was corroborated by medical history. The MDA concentration was lower in normotensive premenopausal; with respect protein damage, all groups presented similar levels, finally, postmenopausal women had lower antioxidant defense. On the other hand, in anthropometry evaluation, only body mass index was (BMI) higher in hypertensive‐premenopausal than on the other groups, while in determinations such as wais‐hip ratio, systolic and dyastolic blood pressures, were similar.

Conclusion: Oxidative stress is increased in hypertensive postmenopausal women and BMI is related to high blood pressure in in hypertensive‐premenopausal women.
Increased memory and decreased naïve T cells in human hypertension (1074.9)
Authors: Marvar Paul , Cruise Tom , Hart Emma , Burchell Amy , Ratcliffe Laura , Nightingale Angus , Paton Julian
Published: June 2021

Studies have revealed a role for pro‐inflammatory effector‐like CD3+ T cells in the pathogenesis of experimental hypertension. Despite these observations, our knowledge of the role that T cells and subsets of T cells (memory vs naïve) play in the development of human hypertension is unknown. We hypothesized that circulating cells of hypertensive patients exhibit a pro‐inflammatory T cell phenotype, as determined by the balance of memory (effector) versus naïve CD3+ cells. Using flow cytometry, subsets of circulating T cells and markers of antigenic memory were analyzed in male hypertensive patients and normotensive subjects. There were no differences in the overall percentage of CD3+ cells in normotensive (63.3 ± 3.7%) (n=5; mean age 34 yrs; mean systolic BP 128.6 mmHg) vs. hypertensive men (62.2 ± 5.5%) (n=6; mean age 53.5 yrs; mean systolic BP 154.7 mmHg). The percentage of CD4+ and CD8+ T cell subsets were not statistically different between groups. Further subset analysis revealed that the ratio (1.6 ± 0.3 vs 0.7 ± 0.1; P <0.05) of memory (CD45RO+CD3+) vs. naïve (CD45RA+CD3+) T cells as well as the percentage of CD8+CD62L(low) cells (70.4 ± 4.5 vs 52.8 ± 6.3; P <0.05) were increased in hypertension. These results demonstrate an imbalance in effector memory / naïve T cells in hypertensive men and provide further evidence that chronic antigen exposure may be involved in the pathogenesis of hypertension. Supported by NIH‐HL107675‐01, Marie Curie‐IIF ‐ 276147 and British Heart Foundation.

Grant Funding Source: NIH‐HL107675‐01, Marie Curie‐IIF – 276147 and British Heart Foundation
Study on penile corpus cavernosum relaxation induced by Berberis amurensis Rupr (1075.10)
Authors: Tan Rui , Kim Hye Yoom , Cho Kyung Woo , Kang Dae Gill , Lee Ho Sub
Published: June 2021

Study on Penile corpus cavernosum relaxation

induced by Berberis amurensis Rupr

Rui Tan 1, 2, , Hye Yoom Kim 1,2, Kyung Woo Cho2, Dae Gill Kang 1,2, and Ho Sub Lee 1,2*

1College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 570‐749, Republic of Korea; 2Hanbang Body‐fluid Research Center, Wonkwang University, Shinyong‐dong, Iksan, Jeonbuk, 570‐749, Republic of Korea

The aim of the present study is to investigate whether a methanol extract of Berberis amurensis Rupr (BAR) augments penile erection. Preconstracted with phenylephrine (PE) in isolated endothelium‐intact rabbit corpus cavernosum, BAR relaxed penile smooth muscle in a dose‐dependent manner, which was inhibited by pretreatment with NG‐nitro‐L‐arginine methyl ester (L‐NAME), a nitric oxide synthase inhibitor, and 1H‐[1,2,4]‐oxadiazole‐[4,3‐α]‐quinoxalin‐1‐one (ODQ), a soluble guanylyl cyclase (sGC) inhibitor. BAR‐induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA), a nonselective K+ channel blocker for BKCa, IKCa and SKCa, and charybdotoxin, iberiotoxin, apamin, a selective Ca2+ sensitive K+ channel inhibitor, respectively. BAR increased cGMP levels of the corpus cavernosum in a concentration‐dependent manner. In addition, BAR caused increase of peak intracavernous pressure (ICP), ICP/MAP ratio and area under the carve (AUC) in a dose dependent manner in SD rats. Taken together, these results suggest that BAR augments penile erection via NO/cGMP system and Ca2+ sensitive‐K+ Channel in corpus cavernosum.
ACE and iNOS overexpression correlates with vascular reactivity in young Syrian cardiomyopathic hamsters (1075.7)
Authors: Cruz Nildris , Quidgley Jose , Dorna Luisamari , Miranda Jorge , Crespo Maria
Published: June 2021

Vascular alterations are present in 2‐month‐old Syrian cardiomyopathic hamsters (SCH) before the clinical manifestation of HF. Aortic ACE, eNOS, and iNOS mRNA and protein levels were assessed in SCH from 1 to 4 months of age to elucidate the timeframe and the mechanisms underlying these alterations. Total RNA and proteins were extracted from aortas, and quantified with Real‐Time RT‐PCR and Western blot. ACE mRNA and protein were upregulated in 2‐month‐old SCH by 41% and 43%, respectively, when compared to control (CT; P<0.05). Protein levels of iNOS were higher in SCH (482%) than in CT (100%) at 2 months of age. In addition, eNOS mRNA increased by 77% in SCH, whereas eNOS protein levels were 15% lower in SCH than in CT (P<0.05). These findings suggest that the vascular reactivity present in 2‐month‐old SCH is secondary to overactivation of RAS resulting from increased levels of ACE mRNA and protein. A combination of lower eNOS and higher iNOS protein levels may underlie endothelial dysfunction present in SCH at this stage. Altogether, these factors will likely promote vascular hyper‐reactivity in the early stages of heart failure in SCH and eventually trigger cardiac deterioration.

Grant Funding Source: Supported by MBRS‐RISE R25‐GM061838
KCNA5 knockout mice demonstrate that Kv1.5 is a component of the native delayed rectifier K+ current in vascular smooth muscle (1077.6)
Authors: Fancher Ibra , Dick Gregory
Published: June 2021

Voltage‐gated K+ channels (KV) mediate physiologically important delayed rectifier K+ (KDR) currents in vascular smooth muscle (VSM). However, the molecular identity of KV subunits that compose KDR channels in VSM remains unclear. We tested the hypothesis that KV1.5 (KCNA5) underlies KDR channels of VSM. To test this hypothesis, whole‐cell patch clamp experiments were performed on VSM from the aortae of wild type (wt) and KV1.5 knockout (KO) mice. Single VSM were bathed in a Ca2+‐free solution (to eliminate inward currents) and dialyzed with a pipette solution containing 10 mM BAPTA (a Ca2+ chelator to minimize Ca2+‐activated currents). The pipette solution also contained 1 uM penitrem A (a BKCa channel antagonist) and 10 uM glibenclamide (a KATP channel antagonist) in order to study KDR in isolation. KDR current in VSM cells from wt mice was 140 ± 47 pA at +20 mV. In contrast, KDR current at +20 was only 68 ± 14 pA in VSM cells from KO mice. KDR was blocked to a greater degree by DPO‐1 (a KV1.5 channel antagonist) in VSM cells from wt mice. Specifically, DPO‐1 (1 uM) inhibited current 61 ± 6 and 26 ± 8% in VSM cells from wt and KO mice, respectively. These data support the hypothesis that KV1.5 subunits are critical components of KDR channels in VSM. Further, the data lead us to suggest that KV1.5‐containing KDR channels may be important in determining the membrane potential of VSM cells.

Grant Funding Source: Supported by T32HL090610
Calcification in vitro: experimental factors that induce nanocrystal formation (1077.9)
Authors: Hortells Luis , Sosa Cecilia , Millán Ángel , Sorribas Victor
Published: June 2021

Medial vascular calcification (VC) of arteries is frequently observed in chronic kidney disease and diabetes. Pathogenesis in VC is frequently studied on primary cultures of aortic smooth muscle cells. However, several experimental factors can affect the rate of calcification in vitro, which can be misleading in the research of VC pathogenesis. The aim of this work has been the identification of these factors and to improve the adequacy of the model.

Calcification was studied as a function of Pi concentration (1‐3 mM), incubation time and media composition (MEM vs. DMEM). We have determined the rate of calcium deposition, medium pH, nucleation rate, degree of crystallization, cell death and osteogene expression.

Calcification was more intense with DMEM than MEM due to increased basicity induced by higher bicarbonate content in DMEM. Cell death (as LDH leakage) correlated and preceded calcification. Particle nucleation depended on pH and Pi concentration, and was already observed after 2h (DMEM) or 5h (MEM) of incubation with the cells. Osteogene expression and crystal structure were also modified by the same experimental conditions.
Mitochondrial calcium is decreased by high glucose and is improved by reduction of protein O‐GlcNAcylation in cardiac myocytes (1078.2)
Authors: Diaz Juarez Julieta , Suarez Jorge , Scott Brian , Dillmann Wolfgang
Published: June 2021

Increased nuclear protein O‐linked β‐N‐acetylglucosamine glycosylation (O‐GlcNAcylation) mediated by high glucose treatment or the hyperglycemia of diabetes mellitus contributes to cardiac myocyte dysfunction. Mitochondrial proteins in cardiac myocytes are also submitted to O‐GlcNAcylation, however, whether excessive O‐GlcNAcylation alters mitochondrial function is incompletely studied. We have previously demonstrated decreased mitochondrial calcium concentration in cardiac myocytes exposed to high glucose. We hypothesize that excessive O‐GlcNAcylation may be responsible of this maladaptive phenomenon and that reducing excessive O‐GlcNAcylation may return mitochondrial calcium levels to normal. Our objective was to test this hypothesis, therefore, we incubated cultured neonatal mouse myocytes in high glucose (HG, 25mM) for 72 hours and inhibited O‐GlcNAcylation by adenoviral expression of a dominant negative mutant of the O‐GlcNAc transferase (dnOGT). As expected, mitochondrial calcium levels were reduced by 20% after HG exposure but were returned to control values after dnOGT expression. In addition, mitochondrial calcium uptake decreased by 52% in HG and was improved by expression of dnOGT, however, did not reach control values. We examined the mitochondrial calcium uniporter (MCU) and found that it is susceptible to be O‐GlcNAcylated and HG further increased O‐GlcNAcylation. In conclusion, our results suggest that excessive O‐GlcNAcylation in hyperglycemia alters mitochondrial calcium homeostasis by increasing O‐GlcNAcylated MCU.

Grant Funding Source: Supported by UC MEXUS and VA‐5 I01BX001121‐02‐
miR‐133a ameliorates cardiac dysfunction in diabetes: possibly by restoring β‐adrenergic receptor function and expression (1078.6)
Authors: Nandi Shyam , Liu Xuefei , Zheng Hong , Sharma Neeru , Chavali Vishalakshi , Patel Kaushik , Mishra Paras
Published: June 2021

Inhibition of microRNA (miR)‐133a causes cardiac hypertrophy and fibrosis. However, the beneficial effects of miR‐133a in cardiac dysfunction remain to be examined. Furthermore, impaired contractility in diabetic hearts has been associated with attenuated expression of β1‐ and β2‐adrenergic receptors (AR). Based on these observations, we hypothesized that augmenting miR‐133a in the circulation will improve cardiac function possibly by enhancing β1‐ and β2‐AR expression in diabetic hearts. Male Sprague‐Dawley rats were injected with streptozotocin (STZ, 45mg/kg, i.v.) to induce diabetes mellitus (plasma glucose >350mg/dL). After 4 weeks these rats were treated with miR‐133a mimic or scrambled control (10^6 lentivirus, i.v.). Two weeks later the left ventricular contractility (dP/dt) were measured under basal conditions and in response to β‐AR agonist isoproterenol (0.05µg/kg, i.v). The miR‐133a treatment increased dP/dt by 25% in diabetic rats under basal condition. In addition, isoproterenol induced increase in dP/dt was significantly increased by administration of miR‐133a in diabetic rats (12618±1086 vs 9256±1103 mmHg/sec). Consistent with these observations mRNA and protein expressions of β1‐ and β2‐AR (measured by RT‐qPCR and immunoblotting) were increased in STZ+ miR‐133a as compared to STZ+ scrambled group (mRNA: β1‐AR, 2.36±0.4 fold and β2‐AR, 3.2±0.4 fold, and protein: β1‐AR, 2.52±0.01 fold and β2‐AR, 4.1±0.01 fold. These results suggest a possible novel beneficial effect of miR‐133a in improving cardiac function in diabetes.

Grant Funding Source: NIH grants: HL113281 and HL116205 and DK82956
Innate collateral vessels in the absence of ischemia undergo shear stress similar to normal arterial segments of the same diameter (1079.12)
Authors: Spaan Jos , van Horssen Pepijn , Sochi Taha , Smith Nic , Siebes Maria , van den Wijngaard Jeroen
Published: June 2021

Some species, including humans, have structural collateral vessels, CV, that can further develop in the presence of coronary stenosis by increasing pressure difference across them. Question is how CV's are maintained in the absence of ischemia.

The coronary network of 6 healthy canine hearts was reconstructed in 3D from images obtained with an imaging cryomicrotome after filling with fluorescent replica material (resolution 0.020 mm). CV's were automatically detected. The full coronary network was reconstructed. For all segments, including CV's, diameter and perfused tissue mass, PTM, was derived and shear stress, SS, calculated.

Innate collateral connections ranged from 286 to 1015 µm in diameter and were distributed over the myocardial wall with some higher density at the subendocardium: density 2.5 ‐ 5.0 per gram tissue. Highly correlating fractal relations were found between PTM and diameter for normal tree segments and for CV's which fully overlapped. SS in the CV's was equal to neighboring tree segments of similar diameter.

Results indicate that collateral segments have the same function in distributing blood, and do so at the same SS, as normal tree segments. Hence, functionally CV's are not different from normal vascular segments and are therefore maintained. CV's form substrate for collateral growth in ischemia.

Grant Funding Source: FP7‐ICT‐2007‐224495: euHeart
Connexin 37 and KCa3.1 contribute to P2Y2 receptor initiated endothelial‐derived hyperpolarization (1079.15)
Authors: Sharik Meaghen , Burt Janis , Ruth Peter , Rieg Timo
Published: June 2021

Nucleotides such as ATP and UTP are important paracrine regulators of vascular tone. Importantly, we previously demonstrated that in vivo activation of P2Y2 receptors (activated by ATP/UTP) causes an acute NO‐independent decrease in blood pressure (BP), indicating this signaling pathway requires an endothelial‐derived hyperpolarization (EDH) response. To define the mechanisms by which in vivo activation of P2Y2 receptors initiates EDH and vasodilation, we studied connexin 37 and 40 (Cx37, Cx40), both part of the myoendothelial gap junction, as well as big‐conductance (KCa1.1, expressed in smooth muscle cells) and intermediate‐conductance K channels (KCa3.1, expressed in endothelial cells), all hypothesized to be part of the EDH response. We compared the effects of the P2Y2/4 receptor agonist, INS45973, in wild‐type (WT) mice and mice lacking Cx37, Cx40, KCa1.1, or KCa3.1 (n=4‐5/genotype) under anesthesia, while monitoring intra‐arterial BP. Acute application of INS45973 (0.01, 0.03, 0.1, 0.3, 1, or 3 mg/kg bw i.v. in 0.5 µl/g bw over 45 sec) dose‐dependently and rapidly (within 15 sec of starting infusion) decreased BP in WT mice (max response % of baseline: ‐38±1%, EC50: 0.8±0.2 mg/kg) for 2‐3 min. Whereas the responses in Cx40‐/‐ and KCa1.1‐/‐ mice were comparable to WT mice (‐41±2%, 0.3±0.1 mg/kg and ‐44±3%, 0.3±0.1 mg/kg, respectively), responses in Cx37‐/‐ and KCa3.1‐/‐ mice were significantly impaired (‐27±1%, 1.2±0.3 mg/kg and ‐13±5%, 1.6±0.8 mg/kg, respectively). Heart rate was not affected in either genotype. Our data indicate that Cx37 and KCa3.1 are required, at least in part, for the P2Y2 receptor‐initiated EDH response and subsequent vasodilation.

Grant Funding Source: 10SDG2610034 and P30DK079337
Pannexin1 channel‐mediated ATP release and the vasodepressor response to hypoxia (1079.19)
Authors: Kirby Brett , Petkov Brian , Zhu Hongmei , McMahon Timothy
Published: June 2021

Plasma ATP is hypothesized to mediate hypoxic vasodilation, and pannexin1 (panx1) channels present in red blood cells (RBCs) and vascular tissue transport ATP in response to hypoxia. We tested the hypothesis that intravascular panx1 channel‐mediated ATP release is obligatory to hypoxia‐induced hypotension in anesthetized mice. Functional loss of panx1‐mediated ATP release to hypoxia was observed in isolated RBCs from mice devoid of panx1 (KO; panx1‐/‐) vs wild‐type controls (WT). Mice were anesthetized with isoflurane, mechanically ventilated, and mean arterial pressure (MAP) was measured via carotid artery catheter during inhalation of 21 and 10% O2. MAP was similar for KO and WT in normoxia, but hypoxia‐induced hypotension was abolished in Panx1‐/‐ vs WT mice (Δ ‐1±3 vs ‐14±3 mmHg). Heart rate during hypoxia did not fall, consistent with hypoxia‐induced peripheral vasodilation. Venous plasma ATP during hypoxia was lower in Panx1‐/‐ vs WT mice (67±6 vs 166±23 nM). These data demonstrate a key role for panx1 channels in governing blood extracellular ATP and the vasodepressor response to hypoxia, consistent with their proposed roles in hypoxic vasodilation.

Grant Funding Source: Supported by NIH HL113943