bluuebunny/crossref_metadata_2025 huggingface dataset:
Aging alters Mitochondrial Respiratory Capacity and Function in Human Skeletal Muscle
Authors: Porter Craig , Hurren Nicholas , Cotter Matthew , Reidy Paul , Dillon Edgar , Durham William , Sheffield‐Moore Melinda , Sidossis Labros , Rasmussen Blake , Børsheim Elisabet
Published: June 2021

Mitochondrial health is critical to physiological function, particularly in tissues with high ATP turnover, such a striated muscle. It has been postulated that derangements in mitochondrial function in skeletal muscle contribute to impaired physical function in older adults. Here, we determined mitochondrial respiratory capacity and function in m. vastus lateralis biopsies obtained from young and older adults.

21 young (28±5 yrs) and 27 older (63±9 yrs) adults were studied. Mitochondrial respiration was determined in permeabilized myofibers after the addition of substrates, inhibitors and uncouplers. Thereafter, flux control ratios and coupling control factors were calculated.

Maximal coupled respiration (P) was higher in muscle from young vs. older subjects (58±3 vs. 44±3 pmol·mg‐1·s‐1, P<0.01), as was maximal uncoupled respiration (E) (63±4 vs. 51±3 pmol·mg‐1·s‐1, P<0.05). Oligomycin sensitivity was lower in older adults (P<0.05), as was the flux control ratio (P/E) (P<0.05). Calculation of respiratory function revealed lower respiration linked to ATP production (P<0.001) and greater residual respiration (P<0.01) in older adults.

Mitochondrial respiratory capacity and function are altered in skeletal muscle of older individuals. In particular, ATP production is less efficient in muscle from older adults. These data suggest a role for skeletal muscle mitochondria dysfunction in senescence.

NIH R01AG033761, R01AR049877, P30AG024832, P30AG028718, UL1TR000071, NIDRR H133P110012, Shriners 84090.
The Effect of Doxorubicin on Mitochondrial Fusion and Fission Markers in the Kidney
Authors: Dirks‐Naylor Amie , Kouzi Samir , Humphrey Morgan , Phan Diep , Whitt Stephanie , Gibson Jacob , Luu Jacqueline
Published: June 2021

Doxorubicin (DOX) is an effective chemotherapeutic agent, but is known to cause significant cardiac and hepatic toxicity. However, there has not been significant research into the effects of DOX on the kidneys. The purpose of this study was to determine if acute DOX treatment affected the content of the primary regulators of mitochondrial fusion and fission. Six‐week old F344 rats were randomly divided into two groups and injected with 20 mg/kg of DOX or saline. Once treated, the animals were fasted with no food or water until sacrifice 24 hours later. Upon sacrifice, kidneys were harvested and stored at ‐80°C for future analysis. MFN‐1, MFN‐2, Fis‐1, OPA‐1 and DRP‐1 were analyzed by Standard Western protocol. Results showed no significant difference in the content of these mitochondrial morphology regulators between the animals treated with DOX and those treated with saline. The results suggest that acute Dox treatment may not affect renal mitochondrial morphology, however further studies including microscopy techniques are required to confirm this conclusion.
Preventive Effects of Electrical Stimulation on Cachexia‐Induced Muscle Mitochondrial Dysfunction
Authors: Tanaka Kohei , Tanaka Minoru , Takegaki Junya , Fujino Hidemi
Published: June 2021

Cachexia is a complex metabolic syndrome associated with underlying chronic diseases. In the cachectic muscle, mitochondrial function is damaged by pro‐inflammatory cytokines, e.g., tumor necrosis factor alpha (TNF‐α). It has been shown that electrical stimulation (ES) prevents mitochondrial dysfunction in skeletal muscle under many conditions. Therefore, the aim of this study was to evaluate the effect of electrical stimulation on cachexia‐induced mitochondrial dysfunction in skeletal muscle. ICR mice (n = 15) were randomly divided into 3 groups; lipopolysaccharide (LPS) injection, and LPS injection plus ES, and age‐matched control group. Cachexia was induced by LPS (10 mg/g body weight, i.p.) for 4 days. ES was conducted twice a day during injected period. LPS injection resulted in increase of the expression of TNF‐α, and decrease of body weight and muscle wet weight. Succinate dehydrogenase (SDH) activity and citrate synthase (CS) activity, the indicators of mitochondrial function, were decreased in the cachectic muscle. On the other hand, the intervention of ES prevented the decrease of muscle wet weight, SDH activity, and CS activity. In addition, it has been shown that p38 mitogen‐activated protein kinase (p38 MAPK) is activated by TNF‐α, and decrease the expression of PPAR gamma coactivator 1‐alhpa (PGC‐1α) which is the mitochondrial biogenesis factor in cachectic muscle. In this study, cachexia‐associated changes in PGC‐1α was prevented by ES via p38 MAPK down regulation. These results suggest that electrical stimulation prevents mitochondrial dysfunction in skeletal muscle induced by pro‐inflammatory cytokines which express in cachexia.
MicroRNA‐21 Ablation Exacerbates Aldosterone‐Mediated Cardiac Injury, Remodeling and Dysfunction
Authors: Syed Maryam , Ball Jana , Mathis Keisa , Hall Michael , Ryan Michael , Rothenberg Marc , Romero Damian
Published: June 2021

Excess aldosterone (ALDO) causes hypertension and cardiac hypertrophy, inflammation and fibrosis that lead to cardiac dysfunction. We previously reported that ALDO/SALT increases left ventricle (LV) miR‐21 expression, but whether this upregulation is protective, deleterious or a bystander is unknown. We used mice with genetic ablation of miR‐21 to study its role in ALDO/SALT‐mediated cardiac hypertrophy, fibrosis and dysfunction.

Uninephrectomized male miR‐21 knockout (miR21KO) or wild‐type (WT) mice were treated with ALDO (0.15 µg/h) and SALT (1.0 % NaCl + 0.3 % KCl) or vehicle for 2 or 8 weeks (N=24/group). Analysis of cardiac tissue by weight and WGA staining revealed ALDO/SALT exacerbated LV hypertrophy (4.6 vs. 4.1 mg/g BW, p<0.05) and LV cardiomyocyte cross‐sectional area (208 vs. 195 µm2, p<0.01) in miR21KO vs. WT mice, respectively. Upregulation of fibrosis markers (Ctgf, collagen I, collagen III, fibronectin, lysyl oxidase), quantified by qRT‐PCR, was exacerbated by ALDO/SALT in miR21KO LV (2‐ to 7‐fold, p<0.05) vs. WT mice. Interstitial (0.46 vs. 0.35 %, p<0.05) and perivascular (0.32 vs. 0.27 %, p<0.05) fibrosis, determined by picrosirius red staining, was exacerbated by ALDO/SALT in miR21KO vs. WT mice. Blood pressure (BP), measured by indwelling carotid artery catheters in conscious mice, was raised to similar levels by ALDO/SALT in miR21KO vs. WT mice.

Our results show that miR‐21 ablation exacerbates ALDO/SALT‐mediated cardiac hypertrophy, fibrosis and dysfunction independently of BP, suggesting that therapies that increase cardiac levels of miR‐21 may benefit patients with excess ALDO.
Effect of Noni Pulp (Morinda citrifolia l.) and Vitamin C in Rats Subjected to Stress by Restriction of Movement
Authors: Lopes Luana , Azevedo Waldir , Teixeira Halbannara , Santos Priscila , Santos Hidelberto , Ogawa Wataro
Published: June 2021

The model of restraint is used to induce stress. Ascorbic acid is a biomarker stored in the adrenal (AAA) whose depletion measures the stress level. Noni has been subject of research because of the potential benefits, but studies associated with stress are scarce, and the pulp seems to contain high levels of vitamin C (VITC). Rats treated with distilled water (gavage) for 14 days were used as controls (C, n = 8); Stress (S, n = 8), treated with distilled water (gavage, 14 days); Noni + stress group (SN, n = 6), treated pulp of noni (gavage, 14 days);Stress + VITC group (SvitC, n = 7) treated with VITC (gavage, 14 days). SN and SvitC received the same dosage of VITC, which in the SN group was determined by titration of the pulp of noni. The procedure was stressful for pet bottles (500 mL) for 1 h / day / 7 days. The adrenal glands were weighed and extracted with AAA metaphosphoric acid. The filtrate was reacted with 2,6‐dichlorophenol indophenol and absorbance reading taken in spectrophotometer (λ = 520 ηm), inserted in the standard curve of ascorbic acid, standardized weights of the adrenals and body. Approval of CEUA under number 017. Data were analyzed using ANOVA and Tukey results show significant depletion of AAA in group S compared to C (p = 0.053) and in groups SN and SvitC no AAA depletion compared to C. It is concluded that possibly the combating stress action noni is due to the vitamin C content in the pulp of this fruit.

Rats
Control Group ugAAA/100mgAdrenal/100gBodyWeight
Stress Group / ugAAA/100mgAdrenal/100gBodyWeight
Stress + Noni Group/ ugAAA/100mgAdrenal/100gBodyWeight
Stress + VITC Group/ ugAAA/100mgAdrenal/100gBodyWeight

1
53,39105339
34,27910812
53,05312158
46,95012019

2
44,24261893
32,64925373
63,42821782
74,2464539

3
52,94006428
38,88750622
60,11479988
55,37917922

4
40,29100547
31,49325827
62,61824905
66,76718701

5
54,11566135
34,78447632
33,83190883
48,97720334

6
48,42196282
37,46436955
44,16282642
40,63548658

7
65,90104111
37,20238095

32,77972028

8
52,1609538
39,11960892

image

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IL‐6 Signaling during Cancer Cachexia Progression: The Female Response
Authors: Hetzler Kimbell , Hardee J , Puppa M , Narsale A , Sato S , Davis J , Carson J
Published: June 2021

Cachexia arises secondary to many chronic diseases and accounts for about 30% of cancer‐related deaths. Cachexia occurs in both sexes, but its etiology and progression have been almost exclusively examined in the male. Interleukin‐6 (IL‐6) has become an attractive therapeutic target as IL‐6 signaling is a recognized regulator of male ApcMin/+ mouse cancer cachexia progression. Despite established sex‐dependent inflammatory responses, how IL‐6 signaling contributes to female cancer cachexia progression is unknown. Consequently, we examined the role of circulating IL‐6 for female ApcMin/+ mouse cancer cachexia progression. Female ApcMin/+ mice weight and functional testing were monitored until sacrifice at 18 weeks of age. A second group of female ApcMin/+ mice underwent IL‐6 overexpression at 15 weeks of age. Blood and hindlimb muscle were collected to examine IL‐6 levels and downstream signaling. Mice were stratified into weight stable, initially cachectic, and severely cachectic groups. Plasma IL‐6 did not differ between groups (17.6 ± 6.7; 34.4 ± 18.9; 39.3 ± 13.1 pg/ml); however, muscle IL‐6 mRNA correlated with body weight loss and hindlimb muscle mass (p=0.008, 0.019). Muscle IL‐6r, gp130, and SOCS3 mRNA expression did not change with cachexia severity. Muscle STAT3 phosphorylation increased with severe cachexia compared to initial cachexia (14.8 ± 1.6 vs 5.2 ± 2.1 fold change relative to WT levels). Surprisingly, IL‐6 over‐expression did not increase muscle IL‐6 signaling or bodyweight loss. Overall, elevated IL‐6 does not exacerbate cachexia progression in the female ApcMin/+ mouse.
Therapeutic Targeting of Akt/mTOR Signaling in Fktn‐deficient Muscle
Authors: Foltz Steven , Patel Ankit , Peissig Kristen , Beedle Aaron
Published: June 2021

Secondary dystroglycanopathies are a subset of muscular dystrophy caused by improper glycosylation of α‐dystroglycan (αDG). Hypoglycosylation of αDG prevents it from binding to laminin and other extracellular matrix receptors, disrupting structural and signaling axes. Mutations in as many as 15 genes have been identified as causative for secondary dystroglycanopathy, including FKTN, which encodes fukutin. We found that mammalian target of rapamycin complex 1 (mTORC1) is activated in muscle of aged Fktn‐deficient mice and that Akt kinase/mTOR signaling is also altered in younger 12 week old knockouts. Chronic inhibition of mTORC1 by rapamycin (RAPA) treatment reduced fibrosis and activity‐induced damage, and increased muscle fiber size in Fktn‐KO mice compared to controls suggesting a delayed disease progression in treated mice. Furthermore, multiple Akt‐related signaling factors showed RAPA‐sensitivity in KO mice, including AMP‐activated kinase α (AMPKα), mTOR, and phosphatase and tensin homolog (PTEN). These findings validate mTOR signaling as a potential therapeutic target, but additional studies are needed to understand and enhance benefits of mTOR inhibition in dystroglycanopathy. This work was funded by the University of Georgia College of Pharmacy.
Chemical Chaperone Therapy Reduces Myofiber Damage in Dystrophin‐null mdx Mice
Authors: Roche Joseph , Mueller Amber
Published: June 2021

Duchenne Muscular Dystrophy (DMD), which affects approximately 1 in 3600 male children, is associated with the absence of the sarcolemmal protein dystrophin, and results in severe muscle weakness, disability and early death. We hypothesize that chronically elevated endoplasmic reticulum (ER) stress is a key player in the pathogenesis of DMD. We therefore predicted that in mdx mice, which model DMD, pharmacotherapy with the chemical chaperone 4‐Phenylbutyric acid (4PBA), which is known to reduce ER stress, will also reduce exercise‐induced muscle damage that is characteristic of dystrophin‐deficiency. In the unexercised tibialis anterior muscle (TA), we found that the ER stress marker CHOP is elevated ~ 3‐fold in mdx versus control mice. Three days after eccentrically‐biased exercise of the TA (90‐180 ° plantarflexion during maximal fused tetany of dorsiflexors; 20 repetitions), there were 9 ± 2 % desmin‐negative damaged fibers in TAs of mdx mice treated with 4PBA (IP injection, 200 mg/kg/day in 0.15M NaHCO3; once daily for 7 days pre‐exercise, daily thereafter until tissue collection) versus 49 ± 7 % damaged fibers in TAs of mdx mice treated with vehicle (N = 2 mice per group); peak tetanic torque of the TA was 75 ± 3 % and 36 ± 3 % of pre‐exercise levels, respectively, in the 4PBA‐ and vehicle‐treated groups (N = 4 mice per group). Data are reported as Mean ± SEM. Our data suggest that relieving ER stress through chemical chaperone therapy might reduce disease severity in patients with DMD.
Effect of long term quercetin supplementation on dystrophic cardiac pathology in mdx/utrn+/‐mice
Authors: Ballmann Christopher , Beyers Ronald , Denney Thomas , Selsby Joshua , Quindry John
Published: June 2021

Duchenne muscular dystrophy (DMD) causes cardiac dysfunction and up to 40% of deaths are attributable to cardiac pathologies. Novel interventions are needed to counter cardiac complications. Recent findings indicate that increased PGC‐1α activity increases utrophin expression, among other benefits, and attenuates disease pathology in dystrophic skeletal muscle. We tested the hypothesis that, quercetin, a SIRT‐1/PGC‐1α activator, would also protect cardiac muscle and alleviate cardiac performance complications in a mouse DMD model. Mdx/utrn+/‐ mice were randomly assigned to standard chow or a 0.2% quercetin enriched diets from 2‐10 months (n=8/group). Age matched C57 mice were fed a control diet. Hearts received 7T MRI to quantify cardiac function at 2 and 10 months of age. Findings confirmed that as compared to C57, mdx/utrn+/‐ mice exhibited diminished cardiac function in a time‐dependent fashion in that end diastolic volume increased at 10 months in both mdx/utrn+/‐ groups (p=0.001). Quercetin enrichment preserved ejection fraction (p<0.001), systolic wall thickness (p=0.006), and fractional shortening (p<0.001) at 10 months of age in mdx/utrn+/‐ mice compared to mdx/utrn+/‐ control fed mice. Quercetin enrichment attenuated increased end systolic volume at 10 months (p<0.001) in mdx/utrn+/‐ quercetin fed mice versus control‐fed mdx/utrn+/‐ mice. Data indicate that quercetin enrichment prevents the age‐dependent cardiac function decline in mdx/utrn+/‐ mice. Additional research should identify the underlying mechanisms and refine quercetin dosing strategies. Funded by Duchenne Alliance.
Upregulation of miR‐21 Restores Cardioprotection under Diabetic Conditions
Authors: Olson Jessica , Yan Yasheng , Bai Xiaowen , Liang Mingyu , Bosnjak Zeljko
Published: June 2021

Introduction

Anesthetic preconditioning (APC) has been shown to decrease myocardial infarct size following ischemia reperfusion injury. This protective effect is attenuated under diabetic conditions, but the underlying mechanisms are largely unknown. MicroRNAs are short, non‐coding nucleotide sequences that suppress and degrade mRNA. Previously, we have shown the functional role of miR‐21 as a novel mediator of APC. Now, we show for the first time its role in attenuated protection seen in diabetic conditions. We hypothesized that upregulation of miR‐21 would restore cardiac protection in animal and human models of diabetes.

Methods

Attenuated APC was investigated in the db/db mouse, the T2DN rat, and in diabetic patient‐derived cardiomyocytes. miR‐21 expression was analyzed using qRT‐PCR and manipulated using GFP‐tagged mimics and antagomirs. Protein expression was examined via Western blot, and cell viability was assessed by propidium iodide staining.

Results

In non‐diabetic models, isoflurane exposure caused a cardioprotective response. This response was abolished in diabetic models, as well as after knockdown of miR‐21. Diabetic models exhibited lower baseline levels of miR‐21 and a significant decrease in expression levels after exposure to isoflurane. This cardioprotective effect was restored using adenoviral‐mediated upregulation of miR‐21.

Conclusions

Our results indicate an important role of miR‐21 in the impairment of APC under diabetic conditions. Further investigation into this phenomenon may suggest new therapeutic targets for reducing perioperative cardiovascular morbidity and mortality in both healthy and diabetic patients.
High fidelity biopotential recordings in mice using a novel telemetry implant
Authors: Guild Sarah‐Jane , Lau Sien Yee , Russell David , McCormick Daniel , Cuddy Helen , Budgett David , Kondo Masahiro , Malpas Simon
Published: June 2021

We have developed a fully implantable telemetry device for use in mice.

The telemeter is able to measure biopotential signals (EEG, EMG, ECG) at a sampling rate of 2000 Hz. The device has a volume of 1.45 cc with a unique contour design for subcutaneous implantation in mice over 20 gm in weight. A novel aspect to the device is that it contains no battery. Power to run the telemeter is provided by a wireless power pad placed under the cage of the animal. This provides continual operation of the telemeter (>90% data collection in a 24 hour period) during a range of normal animal behaviours. We have assessed the ability of this device to record biopotential signals for up to 3 months. We believe this technology offers new experimental paradigms to be explored.
Roles of Intracellular Free Zn2+ on Electrical and Mechanical Activities of the Heart
Authors: Değirmenci Sinan , Tuncay Erkan , Turan Belma
Published: June 2021

Zinc is a vital metal in maintaining cellular functions in many cells and Zn2+ concentration is at the nanomolar range in resting cardiomyocytes. Very little is known about precise mechanisms controlling intracellular free Zn2+ distribution during cardiac function. To understand role of intracellular Zn2+ in cardiac physiology, in the present study, we measured simultaneously twitch tension and action potential (AP) in rat ventricular papillary muscles. The amplitude of twitch tension is 25% depressed while rates of both contraction and relaxation are markedly slowed down during a zinc‐ionophore, Zn‐pyrithione (ZnPT, 1 µM). Repolarizing durations at 25, 50, 75, 90% of AP full repolarization are significantly prolonged during this exposure. The whole‐cell voltage‐clamp technique was applied to isolated ventricular myocytes to investigate the effects of ZnPT exposures on L‐type Ca2+ channel currents (ICaL). In presence of Ca2+, Zn2+ exposures demonstrated strong inhibitory effects on ICaL with significant alteration in voltage dependency of the channels and a hump at around ‐40 mV in the current‐voltage relationship. Additionally, our preliminary data indicated that intracellular free Zn2+could inhibite a steady‐state K(+) current which modulates excitability and AP duration in cardiomyocytes. Therefore, our results suggested that an intracellular Zn2+ increase can induce depressed electrical and mechanical activity of cardiac preparations, in most, its modulatory action on transmembrane Ca2+ movements. Of note, in many pathological situations, including diabetes, the intracellular Zn2+ is increased, our results help to explain one of underlying mechanisms associated with cardiac dysfunction in these diseases.

(Supported by grant from TUBITAK SBAG‐113S466)
Cardiac MuRF1 regulates PPAR‐α agonist‐induced spontaneous cardiac hypertrophy in vivo
Authors: Parry Traci , Desai Gopal , Stanley Natalie , Schisler Jonathan , Willis Monte
Published: June 2021

The ubiquitin proteasome system is a protein degradation system mediated in part by the muscle ring finger‐1 (MuRF1) ubiquitin ligase. MuRF1 has been shown to play an important role in cardiac hypertrophy. MuRF1 also targets and inhibits PPAR‐α activity, with MuRF1‐/‐ hearts showing increased PPAR‐α activity in vivo. The unique duality of MuRF1′s regulation of cardiac hypertrophy and PPAR‐α's activity led us to determine the in vivo effect of MuRF1 on PPAR‐α signaling. This was done by challenging them with fenofibrate, a PPAR‐α agonist. MuRF1‐/‐ and age matched sibling MuRF1+/+ controls received standard chow or fenofibrate chow (0.5% w/w). Echocardiography determined cardiac function at 3 and 8 weeks, followed by cardiac tissue analysis by RT‐PCR, histology, and electron microscopy. Fenofibrate induced a time dependent increase in cardiac hypertrophy, evidenced by significant (P<0.05) increases in cardiac wall thickness and cardiomyocyte cross sectional area in MuRF1‐/‐ mice (25% increase vs MuRF1+/+). Pathological hypertrophy genes beta‐myosin heavy chain, smooth muscle alpha‐actin, and brain natriuretic peptide were also increased in fenofibrate fed MuRF1‐/‐ mice. Additionally, fenofibrate fed MuRF1‐/‐ mice exhibited increased lipid filled vesicles in and around mitochondria as well as increased mitochondrial fallout compared to fenofibrate fed MuRF+/+ mice. These findings suggest that cardiac hypertrophy associated with PPAR‐α agonist fed MuRF1‐/‐ mice appear to be pathological in nature. These data also show, for the first time, the interplay between MuRF1, PPAR‐α, and hypertrophic cardiomyopathy pathways, indicating a unique role for PPAR‐α in cardiac hypertrophy.
In Utero PM2.5 Exposure Contributes to Adult Cardiac Dysfunction
Authors: Tanwar Vineeta , Gorr Matthew , Eichenseer Clayton , Wold Loren
Published: June 2021

The present study was designed to investigate the effects of in utero exposure to PM2.5 on the adult cardiac functions. Female FVB mice were exposed either to filtered air (FA) or particulate matter (PM2.5) at concentration of 51.69 μg/m3 for 6 h/day, 7 days/wk throughout pregnancy. To examine cardiac function, male offsprings at 12 weeks of age underwent a baseline echocardiographic assessment. Following sacrifice, cardiomyocytes were isolated to assess cardiac dysfunction at cellular level using IonOptix. LV tissue from separate group of mice was used to isolate mRNA and protein to study underlying mechanisms. Mice exposed to PM2.5 in utero demonstrated increased LVESd and LVEDd dimensions and reduced PWTs. Morphological alterations were associated with lower systolic function as indicated by reduced FS in PM2.5 exposed mice compared to FA controls. Cardiomyocytes isolated from PM2.5 exposed hearts showed reduced %PS compared to FA exposed hearts. ‐dL/dt was significantly reduced whereas +dL/dt, TR90 and TPS90 remain unchanged between the groups. qPCR analyses revealed decreased TNF‐α, increased IL‐1ß, collagen I and MMP9 expression in one‐day‐old mice exposed to PM2.5 in utero compared to FA. Western blot analyses demonstrated modified NCX, SERCA and PLN expression in PM2.5 compared to FA exposed hearts. Mass spectrometry revealed differential expression of proteins involved in maintaining cardiac physiological functions in PM2.5 compared to FA exposed hearts.

Conclusions

In utero PM2.5 exposure triggers an inflammatory and profibrotic response and alters Ca2+ homeostasis (through NCX, SERCA and PLN hypophosphorylation) thereby promoting adult cardiac dysfunction.
Aerobic Exercise (EX) Training Does Not Improve Body Composition or Glycemic Control in Type 2 Diabetic Rats with Pulmonary Hypertension (PH)
Authors: Baum Jamie , Smith‐Blair Nan , French William , Washington Tyrone , Greene Nicholas
Published: June 2021

Chronic obstructive pulmonary disease (COPD) and Type 2 Diabetes Mellitus (T2D) are among the 10 leading causes of death in the US. 14‐15% of COPD patients admitted to the hospital have T2D. PH is a common complication of COPD, but there is limited data on the prevalence of PH in patients who also have T2DM. There is very little literature on the impact EX may have on these patients. The study objective study was to determine the effect of EX training on glycemic control and skeletal muscle function in T2D with PH. 12‐week old, male obese Zucker (O) and lean, age‐matched Zucker controls (L) were used in this study. Rats were randomized into EX (15m/min; 20o slope) or sedentary groups and were given a dose of monocrotaline (40 mg/kg bw) to induce PH or saline placebo. The EX intervention lasted 8 weeks. At 8 weeks, animals were fasted overnight and plasma and tissues were collected. There was no difference in total weight gain and final body weight in rats within the O or L groups. There was significant difference (P<0.05) between final O and L body weights and weight gain. O had lower (P<0.05) muscle mass than L. There was a trend for EX to reduce body fat in both groups. There was no difference in fasting insulin or glucose between treatments, however there a trend for higher values in O. O with PH and EX had higher (P<0.05) plasma levels of leucine, isoleucine and valine than sedentary. In conclusion, aerobic exercise training does not impact body composition or glycemic control in T2D with PH. Funded by Arkansas Biosciences Institute.
Western Diet Increases Penile in vivo Reactive Oxygen Species: Investigation of Antioxidant Defense
Authors: La Favor Justin , Luke Nathan , Hannan Johanna , Burnett Arthur
Published: June 2021

Excessive production of reactive oxygen species (ROS) has consistently been described as a cause of erectile dysfunction (ED), though assessments are often made by indirect byproducts in excised tissue. Under conditions of elevated ROS, many tissues will upregulate the antioxidant defense system as a protective mechanism, though this mechanism is understudied in the penis. The objective of this study was to utilize a novel technique to measure in vivo ROS in the penis of rats, and to investigate the expression of antioxidant and anti‐inflammatory genes following 12 weeks of a control diet (CD) or WD. Following dietary intervention (n = 6 CD; n = 6 WD), a microdialysis probe was inserted into the penis of rats under anesthesia. To measure ROS, probes were perfused with saline containing Amplex Ultrared, horseradish peroxidase, and superoxide dismutase (SOD), and fluorescence measured at the outlet. Penile hydrogen peroxide (1.31 vs. 1.96; p = 0.014) and superoxide (1.86 vs. 2.39; p = 0.029) were elevated in response to the WD. The NADPH oxidase subunit p22phox was increased in WD penes (0.36 vs. 0.51; p = 0.038), while a trend of increased p67phox (0.45 vs. 0.63; p = 0.079) was observed in WD. Of the 11 antioxidant genes investigated, only SOD1 was upregulated in WD (0.98 vs. 1.17; p = 0.03), although expression of the anti‐inflammatory gene heme‐oxygenase 1 (HO‐1) was decreased in WD penes (1.74 vs. 0.96; p < 0.01). In conclusion, NADPH oxidase is a probable source of excessive ROS in WD induced ED, while a modest antioxidant defense response may contribute to redox imbalance in the penis. Downregulation of HO‐1 following WD may exacerbate ED through promotion of inflammation.

Supported by a fellowship grant from the Sexual Medicine Society of North America.
Metabolic and Mitochondrial Gene Expression Changes in the Aging Heart
Authors: Barton Gregory , McKiernan Susan , Aiken Judd , Diffee Gary
Published: June 2021

Substrate utilization favors fatty acid oxidation in normal healthy hearts. Aging is associated with attenuated mitochondrial biogenesis and fatty acid metabolism in the heart, but the mechanism of these changes remains unclear. Very little information is available on the effects of aging on expression of genes related to fatty acid and glucose metabolism, as well as genes related to mitochondrial function. Exercise has been shown to increase expression ofkey genes related to fatty acid metabolism and mitochondrial metabolism. We determined gene expression differencesin hearts of Young, Old, and Old + Exercise FBN rats, using Qiagen PCR arrays for Glucose, Fatty acid, and Mitochondrial metabolism. Old rats demonstrated decreases (p < 0.05) for key genes in fatty acid transport and β‐oxidation such as (CPT‐1c, CPT‐2, Hadha, Fabp3, Lpl, FATP). Old rats also showed significant decrements in genes involving mitochondrial biogenesis, electron transport, as well as AMPK signaling. There were no differences in the expression of genes involving glucose metabolism with age. Four months of exercise training was unable to attenuate the decline in the gene expression changes in aged hearts. Our data suggest substantial changes to fatty acid and mitochondrial metabolic gene expression with age as a mechanism for alterations in substrate utilization.

Supported by NIH AG 030423
RAAS Activation Aggravates Ischemia Reperfusion Injury and Accelerates Progression to Chronic Kidney Disease
Authors: Greite Robert , Chen Rongjun , Baniassad Bita , Rong Song , Thorenz Anja , Meier Martin , Tewes Susanne , Hüper Katja , Güler Faikah
Published: June 2021

Objective

– Ischemia reperfusion injury (IRI) leads to acute kidney injury (AKI) after major surgery and contributes to progressiverenal fibrosis. Activation of the RAAS system and hypertension arecharacteristics of AKI. However, the most frequently used mouse strain (C57Bl6) in IRI research lack blood pressure elevation after IRI. WecomparedCD1 mice with C57Bl/6 mice in the model of IRI induced AKI and the effects of RAAS activation.

Methods

– IRI was induced by clamping of the renal pedicle for 35 min. Renal function, glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by inulin/PAH‐clearance. Morphology was investigated and immunohistochemistry for myeloid cell infiltration and collagen expression was done. MAPkinase acitvation was analysed by WB. Systemic blood pressure was assessed by tail cuff measurement. Functional MRI to quantify renal perfusion impairment and tissue edema was done.

Results

– CD1 mice showed severe blood pressure elevation of 20 mmHg after IRI. Creatinine elevation was 4 fold and comparable between C57Bl6 and CD1 mice at d1 after IRI. CD1 mice were more sensitive to hypoxic injury and showed pronounced tissue swelling at d1 correlating with edema formation in the MRI. CD1 mice developed persistent impairment of RBF and rapid progression to CKD. C57Bl6 mice were able to regenerate, normalize RBF and had only minor renal scaring after 4 weeks.

Conclusion

CD‐1 mice are very sensitive to hypoxic renal injury and develop show severe blood pressure elevation which accelerates the progression to CKD. The CD1 mouse model offers the opportunity to study RAAS activation in the context of IRI.
Inhibition of cGMP Degradation contributes to the Cardioprotective Effect of Resveratrol on Ischemia/Reperfusion Injury
Authors: Xi Jinkun , Fei Shuo , Xu Zhelong
Published: June 2021

Resveratrol is cardioprotective and our previous study demonstrated that resveratrol prevents reperfusion injury by targeting mitochondrial permeability transition pore (mPTP) throughthe cGMP/PKG signaling pathway. Nevertheless, the exact mechanism by which resveratrol activates the cGMP/PKG pathway remains unclear. The cGMP level is regulated by both guanylyl cyclase that promotes the synthesis of cGMP using NO and phosphodiesterase (PDE)which induces the hydrolysis of cGMP. We aimed to explore the mechanism by which resveratrol increases cGMP leading cardioprotection, focusing on the roles of NO and PDE5. Exposure of rat cardiomyocytes to 10 µM resveratrol for 10 min did not show an increase in DAF‐FM fluorescence , indicating that resveratrol does not produce NO. In contrast, resveratrol reduced PDE5 activity and increased cGMP levels at reperfusion in the heart, indicating that the cardioprotective effect of resveratrol is not mediated by guanylyl cyclase but is dependent on PDE5. The non‐selective PDE inhibitor IBMX given at reperfusion could mimic the cardioprotective effect of resveratrol by reducing infarct size in isolated rat hearts, an effect that was reversed by mPTP opener atractyloside, indicating that resveratrol modulate the mPTP opening through inhibition of PDE. In addition, resveratrol enhanced the phosphorylation of VASPand GSK‐3β, an effect that was partially blocked by PKG inhibitor KT5823. In conclusion, these data suggest that inhibition of PDE5 leading to the increase in intracellular cGMP, which accounts for the cardioprotective effect of resveratrol on reperfusion injury through prevention of the mPTP opening via the cGMP/PKG/GSK‐3β signal pathway.
Angioadaptive Allies: Relationship Between Human Primary Endothelial Cells And Human Skeletal Muscle Myofibroblasts
Authors: Ciccone Joseph , Alinejad Yasaman , Aiken Julian , Despatis Marc‐Antoine , Balg Frederic , Roudier Emilie , Grenier Guillaume , BIROT Olivier
Published: June 2021

Angioadaptation is the ability of capillaries to adapt to physiological changes. This is influenced by interactions between endothelial cells (EC) and supporting cells such as myofibroblasts (MF).

Objective

We examined a possible pro‐angiogenic paracrine interaction between newly identified MF progenitors in human skeletal muscle and primary EC, and how this interaction may be altered under hyperglycemic conditions.

Methods

Human skeletal muscle MF progenitor cells (CD90+) were sorted by FACS and differentiated into MF using TGFb under normo‐(NG) or hyperglycemic (HG) conditions. The expression level of 55 angioadaptive proteins was measured by proteome array in the conditioned media (secretome). Human microvascular EC were treated with secretome. VEGF‐A and TSP‐1 mRNA levels were measured by qPCR in these cells. EC migration was evaluated in the Boyden Chamber assay.

Results

The secretome from differentiated MF was enriched in pro‐angiogenic factors compared to CD90+ cells. VEGF‐A mRNA expression was increased in EC when treated with MF secretome and their migration was stimulated. In contrast, CD90+ cell differentiation under HG resulted in decreased pro‐angiogenic factor secretion in MF secretome and reduced EC migration.

Conclusion

MF exert some pro‐angiogenic stimulation on primary EC compared to progenitor cells. This pro‐angiogenic effect is attenuated when cell differentiation occurs under HG. Funding: CIHR/NSERC.
Activation of Retrotrapezoid Nucleus (RTN) Maintains Normal Breathing in Hyperoxia Despite the Loss of Carotid Body (CB) Input
Authors: Basting Tyler , Burke Peter , Stornetta Daniel , Stornetta Ruth , Guyenet Patrice
Published: June 2021

Rationale and objectives: the CBs contribute greatly to resting ventilation in conscious mammals. For example, their excision produces large and long‐lasting breathing reductions. Yet sustained hyperoxia, which silences the CBs, produces minimal breathing reductions in conscious rats and mildly activates breathing in man. RTN is a major cluster of central respiratory chemoreceptors (CRCs). Here we tested whether, under hyperoxia, breathing might be maintained by a compensatory increase in RTN activity.

Methods: RTN and nearby C1 neurons were bilaterally transduced with archaerhodopsin (PRSx8‐ArchT‐EYFP‐LVV). We first showed that RTN neurons were instantly silenced by green light in anesthetized rats. We then measured the effect of RTN inhibition (10s) on breathing (fR, VT) and BP in conscious rats exposed to normoxia (21% FiO2) or hyperoxia (65% FiO2). Arterial blood gases (PO2, PCO2), pHa and HCO3 were measured under both conditions.

Results: hyperoxia produced a very mild respiratory acidosis. RTN inhibition elicited a much larger fR and VT reduction in rats exposed to hyperoxia than to normoxia. BP was unaffected under hypoxia or hyperoxia suggesting that the C1 neurons were minimally impacted by the light.

Interpretation: in conscious rats hyperoxia activates RTN, which maintains ventilation at control level (normoxia) despite the presumed loss of CB activity. RTN activation by hyperoxia probably results from several mechanisms including mild respiratory acidosis, Haldane effect and CNS vasoconstriction, the latter causing reduced CO2 wash‐out and brain parenchymal acidification. Funding: HL074011 (PGG), 5T32HL007284‐38 (TMB).
Ginsenoside Rb1 Attenuates Pulmonary Arterial Contraction to Agonist via Inhibiting Store‐operated Calcium Entry in Control and Pulmonary Hypertension Rats
Authors: Lin Mo‐Jun , Wang Rui‐Xing , He Rui‐Lan , Jiao Hai‐Xia , Dai Mao , Mu Yun‐Ping , Sham James
Published: June 2021

This study was designed to investigate the effects and mechanisms of ginsenoside Rb1 on pulmonary arteries (PAs) and pulmonary arterial smooth muscle cells (PASMCs) in control and pulmonary hypertension (PH) rats. Isometric tension inPAs, intracellular Ca2+ concentration ([Ca2+]i) and Mn2+ quenching of Fura‐2 in the PASMCs f were measured from control and two widely used models of chronic hypoxia (CH)‐ and monocrotaline (MCT)‐induced PH rats. The results showed that ginsenoside Rb1‐induced dose‐dependent relaxation (0.1‐300 µM, EC50=6 µM ) on PAs precontracted with endothelin‐1 (ET‐1) of control rats. Pretreatment with 6 μM ginsenoside Rb1 attenuated PAs contraction induced by a store‐operated calcium entry (SOCE) activator, 10μM cyclopiazonic acid (CPA) and 10 nM ET‐1 on control, CH‐ and MCT‐treated rats, respectively. 6 μM Ginsenoside Rb1 also induced vasorelaxation of PAs precontracted with 10μM CPA and 10 nM ET‐1 on control, CH‐exposed and MCT‐treated rats, respectively. Moreover, after a SOCE blocker, 20 nM Gd3+ decreased pre contraction induced by 10 nM ET‐1, 6 μM ginsenoside Rb1 can not significantly reduce the PAs contraction again. 6 μM ginsenoside Rb1 significantly decreased 10μM CPA‐induced Ca2+ transients and cation entry by Mn2+ quenching in PASMCs of control, CH‐ and MCT‐ groups. We concluded that ginsenoside Rb1 may take a PAs relaxation via inhibiting SOCE on control, CH‐exposed and MCT‐treated rats. The vasorelaxation of ginsenoside Rb1 in CH‐ and MCT‐induced PH rats may provide a new insight for curing PH.
Transcriptomic and Epigenomic Reponses During Human Adaptation to High‐Altitude Hypoxia
Authors: Roach RC , Dvorkin D , Julian C G , Gronewold J , Bourdillon N , Bucher J , Elliott JE , Evero O , Fan JL , Jameson‐Van Houten S , Kayser B , Kern JP , Kim SE , Laurie SS , Lovering A T , Ryan B , Wachsmuth NB , Subudhi A W
Published: June 2021

Little is known about early genomic responses in human adaptation to high‐altitude hypoxia. At 5260 m (PB=406 Torr) we studied transcriptomic and epigenomic responses of 21 young, healthy men and women during 16 days, and again on return after 7 days in normoxia. Physiological responses showed marked improvement in performance at day 16 compared to day 1, with better SaO2%, submaximal work capacity and cognitive function, and complete protection from altitude illness. Most of these improvements were maintained after 7 days in normoxia. Accompanying these changes, 6350 genes were differentially expressed (DE, q<=0.01) from sea level (SL) on day 7/16, with 3557 (48%/52% up/down) only on day 7 (early), 1418 at both day 7 & 16 (40%/60% up/down), and on day 16 (late) 1375 (44%/56% up/down). Differential methylation (DM, q<0.01) was also observed genome‐wide, and followed a similar time pattern. The DE and DM genes include many known hypoxia‐responsive genes (HIF1α, HIF2α, VEGF, HMOX, etc.). Surprisingly, 1608 genes were DM from SL to day 16, and maintained their DM status after 7 days in normoxia, making these genes prime candidates for control of the onset and retention of physiological adjustments to hypoxia. These data provide a unique resource for future exploration of the molecular and cellular mechanisms controlling human adaptation to hypoxia. Funding for AltitudeOmics was provided, in part, by US DoD W81XWH‐11‐2‐0040 (RCR).
Greater β‐Adrenergic Vasodilation in Healthy Men Versus Women: Cyclooxygenase Suppresses Nitric Oxide
Authors: Peltonen Garrett , Johansson Rebecca , Limberg Jacqueline , Harrell John , Ernst Brady , Kellawan Jeremy , Crain Meghan , Eldridge Marlowe , Sebranek Joshua , Walker Benjamin , Schrage William
Published: June 2021

Data suggest women exhibit greater β‐adrenergic receptor (β‐AR) mediated regulation of blood pressure than men. We tested the hypothesis that peripheral β‐AR vasodilation is greater in women, due in part to nitric oxide synthase (NOS) and cyclooxygenase (COX) signaling. In 22 healthy adults (10 men, 12 women; 24±2 yrs) forearm blood flow (FBF) was measured by Doppler ultrasound during graded brachial artery infusion of the β‐AR agonist isoproterenol (ISO: 3, 6, and 12 ng 100 ml lean tissue‐1 min‐1). Three ISO trials were performed: 1) ISO (control), 2) ISO with NOS or COX inhibition [L‐NMMA (n=10) or ketorolac (n=12), respectively, in counterbalanced order] followed by, 3) ISO with combined NOS + COX inhibition (double blockade – DB, n=22). Forearm vascular conductance was calculated (FVC = FBF/MAP) and the rise in FVC with ISO infusion (DFVC; infusion – baseline) quantified β‐AR vasodilation. Contrary to our hypothesis, DFVC with ISO was greater in men than women (p=0.02). L‐NMMA decreased DFVC from control (p=0.02) but did not eliminate the sex difference (p=0.01). Ketorolac increased DFVC above control (p<0.01), and abolished the sex‐difference (p=0.39). DB decreased DFVC below control (p=0.03) such that DFVC was again greater in men than women (p=0.01). We conclude: 1) β‐AR vasodilation is greater in young men vs women, 2) COX signaling limits β‐AR vasodilation more in women, and 3) COX appears to suppress NOS in both sexes, but more in women. These data are the first to demonstrate COX‐mediated restraint of β‐AR vasodilation in humans, and highlight sex differences in β‐AR control.

Support: NIH R01 HL105820
Role of TNF‐α in Regulating Augmented Exercise Pressor Reflex Induced by Femoral Artery Occlusion
Authors: Lu Jian , Xing Jihong , Li Jianhua
Published: June 2021

Using a rat model, our prior study has demonstrated that TNF‐α contributes to augmented sympathetic nerve and blood pressure responses evoked by activation of metabolic receptors (i.e., TRPV1 and TRPA1) on thin fiber muscle afferent nerves when the blood flow to hindlimb is occluded for 72 hrs. The present study was to examine the role played by TNF‐α in augmented sympathetic responsiveness during the exercise pressor reflex following 72 hrs of femoral artery occlusion. The exercise pressor reflex was evoked by static muscle contraction and passive tendon stretch in rats. Our results show that femoral occlusion significantly enhanced blood pressure response to muscle contraction and stretch (P<0.05) as compared with controls. TNF‐α synthesis suppressor pentoxifylline (PTX) administered previously into the hindlimb muscles significantly attenuates amplified blood pressure response induced by muscle contraction in occluded rats (MAP: 19±1 mmHg with PTX and 26±2 mmHg without PTX, n=6 in each group; P<0.05 vs. PTX group). However, PTX failed to significantly alter amplified pressor response induced by muscle stretch in occluded rats (MAP: 21±2 mmHg with PTX and 23±2 mmHg without PTX, n=5 in each group; P>0.05 vs. PTX group). Overall, our data suggest that TNF‐α plays a role in modulating augmented sympathetic responsiveness via the metabolic component of the exercise pressor reflex when arterial blood supply to the hindlimb is deficient under ischemic conditions as observed in peripheral artery disease. This study was supported by NIH P01 HL096570
Responses of thin fiber muscle afferents to contraction are greater in ligated than in freely perfused rats
Authors: Stone Audrey , Copp Steven , Kaufman Marc
Published: June 2021

Previous evidence has shown that ligating the femoral artery for 72 hours resulted in an exaggerated exercise pressor reflex. Nevertheless, electrophysiological evidence concerning the afferent arm of the reflex that is supportive of this exaggeration is lacking. Consequently, in decerebrated rats whose femoral arteries were either freely perfused or ligated for 72 hours, we compared the responses of thin fiber (i.e., group III & IV) muscle afferents to static contraction of the hindlimb muscles. We found that contraction in freely perfused rats increased thin fiber afferent activity (mean conduction velocity: 3.8±0.5 m/s) from 0.3±0.1 imp/s to 0.8±0.2 imp/s (n=26; p<0.05). In contrast, in ligated rats contraction increased afferent activity (mean conduction velocity: 3.4±0.6 m/s) from 0.4±0.1 imp/s to 1.4±0.1 imp/s (n=22; p<0.05). The contraction induced increase in thin fiber afferent activity was significantly greater in ligated rats than that in freely perfused rats (p<0.05). Stretch stimulated 12 of 17 group III afferents in freely perfused and 7 of 12 group III afferents in ligated rats. Nevertheless, each of these 29 group III afferents responded to contraction. In contrast, stretch did not stimulate any group IV afferents in either freely perfused or ligated rats. We conclude that static contraction stimulates thin fiber muscle afferents to a greater extent in ligated rats than that in freely perfused rats. This finding provides an electrophysiological basis for the exaggeration of the exercise pressor reflex by chronic obstruction of femoral artery blood flow. In addition, this finding may provide a basis for the exaggerated exercise pressor reflex seen in peripheral artery disease. Funding: NIH AR‐059397, HL‐096570
Protecting against ischemic stroke in rats by heat shock protein‐20‐mediated exercise preconditioning
Authors: Liu Yu‐Fan , Lin Jia‐Wei , Tu Hui‐Yuan , Chang Ching‐Ping
Published: June 2021

The small heat shock protein (HSP) 20 is expressed in the brain, stomach, liver, lung, kidney, blood smooth muscle, skeletal muscle, and cardiac tissue. This study provides the new finding on translocation of HSP20 in response to exercise preconditioning with special emphasis on its protection effects in ischemic stroke. Here, we report that, in a rat model of ischemic stroke, exercised rats (given pre‐stroke exercise) had significantly higher levels of neuronal and astroglial HSP20, a lower functional deficit, fewer brain ischemia, and fewer apoptotic cells than did non‐exercised rats. pSUPER plasmid expressing hsp20 small interfering RNA (siRNA‐hsp20) was injected into the injured brains. In addition to reducing neuronal and astroglial HSP20, the (siRNA‐hsp20) significantly reduced the beneficial effects of exercise preconditioning in attenuating functional deficit as well as brain infarction and apoptosis. It can be derived from the present results that exercise preconditioning may facilitate functional recovery from ischemic stroke by pre‐induction of HSP20 in brain.