bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel relationship between estrogen, insulin resistance, and cardiovagal baroreflex sensitivity in obese PCOS women
Authors: Miner Jennifer Ann , Miner Jonathon Cory , Brunt Vienna Elizabeth , Kaplan Paul F. , Minson Christopher Todd
Published: June 2021

To assess the impact of hormonal treatment (a first‐line of treatment for polycystic ovary syndrome, PCOS) and insulin resistance on cardiovagal baroreflex sensitivity (CVBR), we suppressed endogenous estrogens and progesterone in obese PCOS women (n=3) for 10 days using a gonadotropin‐releasing hormone antagonist, and used an exogenous hormone add‐back design to isolate the effects of 0.2 mg/day transdermal estradiol (Trial 2) versus combined estradiol and 200 mg/day oral progesterone (Trial 3). CVBR was assessed during hormone suppression (Trial 1) and during the hormone add‐back conditions via intravenous administration of sodium nitroprusside and phenylephrine using the Modified Oxford technique, and was analyzed relating R‐R interval and systolic blood pressure. We also conducted an oral glucose tolerance test to assess insulin resistance across all subjects. CVBR was higher in the estradiol‐alone condition (21.85 ± 1.86, p=0.01), compared to the hormone suppression (12.32 ± 2.27) and combined hormone conditions (12.27 ± 1.56). Across all trials, CVBR was predicted by a linear combination of estrogen level (p=0.01) and level of insulin resistance (p=0.02), as determined by their HOMA score (R2=0.80). These data suggest that in obese PCOS women, who have higher levels of insulin resistance, estrogen administration may improve baroreflex sensitivity. Supported by NIH Grant HL081671.
The Exaggerated Exercise Pressor Reflex in Heart Failure: MAPK Activation in Peripheral Dorsal Root Ganglia
Authors: Wang Hanjun , Wang Wei , Rozanski George J. , Zucker Irving H.
Published: June 2021

An exaggerated exercise pressor reflex (EPR) causes excessive sympatho‐excitation and exercise intolerance during physical activity in the chronic heart failure (CHF) state. Peripheral sensitization of muscle mechanoreceptors (mechanoreflex) is an important contributor to the exaggerated EPR in CHF whereas the metaboreflex is blunted. The molecular mechanisms underlying the selective sensitization of the mechanoreflex in CHF remain unclear. Here, we proposed that excessive activation of the mitogen‐activated protein kinases (MAPK) pathway in afferent neurons plays a critical role in mediating the sensitized EPR in CHF. Our data demonstrate that phosphorylation of ERK1/2 and p38 but not JNK is increased in lumbar dorsal root ganglia (DRG) of CHF rats compared to sham rats. Furthermore, we found that 1‐ week epidural administration of either the ERK inhibitor PD98059 or the p38 inhibitor SB203580 to lumbar DRGs attenuated the pressor response to either static contraction induced by electrical stimulation of L4/L5 ventral roots or passive stretch (a purely mechanical stimulus) in CHF rats but not in sham rats. Neither treatment improved the blunted cardiovascular responses to hindlimb arterial injection of capsaicin in CHF rats. These data suggest that the increased activation of MAPK pathways in muscle afferent neurons contributes to the genesis of the exaggerated EPR as well as the mechanoreflex in CHF.
Glycemic control by the brain renin‐angiotensin system: Role for peripheral AT2 receptors
Authors: Weidemann Benjamin J. , Littlejohn Nicole K. , Sigmund Curt D. , Grobe Justin L.
Published: June 2021

The effect of hyperactivity of the brain renin‐angiotensin system (RAS) on metabolism was explored using double‐transgenic “sRA” mice, which express human renin via the synapsin promoter and human angiotensinogen via its own promoter. sRA mice exhibit hypertension, polydipsia, and elevated resting metabolic rate (RMR). Compared to control littermates (n=9), body mass was lower in sRA (n=9) mice (25.11±1.26 vs 18.95±0.87 g, P<0.05), and i.p. glucose tolerance (ipGTT, 2 g/kg total body) was improved (genotype x time P=0.03). Lean mass by NMR was reduced in sRA (16.54±0.79 vs 12.62±0.63, P<0.05), but proportional lean mass was normal (66.1±.52 vs 66.69±1.48 % total). Lean ipGTT (2g/kg lean body, P=0.29) was normal, and tolerance to a bolus dose of glucose was reduced (28 mg/mouse, P<0.001). sRA mice were more sensitive to insulin, as i.p. insulin (0.5 U/kg total body) caused dramatic drops in blood glucose (control nadir 72±8 vs sRA nadir 27±5 mg/dL and occasionally death, genotype x time P<0.02). As the RMR increase in sRA is mediated through suppression of adipose AT2 receptor activation, we tested the effects of chronic infusion of CGP‐42112a (50 ng/kg/min) on ipGTT. Chronic CGP‐42112a significantly reduced ipGTT (2 g/kg total body, AUC +23%, P=0.008) in both control and sRA mice. Together, these data suggest that the brain RAS may improve glycemic control through tonic suppression of peripheral AT2 activation.
A monoclonal antibody targetting the FGFR‐1c isoform reduces body weight and food intake, which is, associated with a suppression of deiodinase 2 mRNA expression in hypothalamic tanycytes
Authors: Samms Ricardo , Lory Alex , Roberts Jessica , Warner Amy , Sundquis Sarah , Emmerson Paul , Perry Barrett , Tsintzas Kostas , Ebling Fran
Published: June 2021

FGF21 plays a role in the peripheral regulation of energy balance, but its putative receptor (FGFR1c) is also expressed in tanycyte cells of the hypothalamus. The objective of the present study was to investigate the possible central actions of a monoclonal antibody (H7) that specifically targets FGFR1c in a natural model of adiposity, the Siberian hamster. Hypothalamic thyroid hormone availability, controlled by tanycytes, is the key regulator of seasonal cycles of body weight, so we aimed to determine the effect of H7 on local regulators of thyroid hormone availability: deiodinase enzymes DIO2 and DIO3. Hamsters maintained in their long day fat state (LD; n=12) or short day lean state (SD; n=12) were treated with H7 (n=6, 3 mg/kg, sc) or vehicle (n=6/photoperiod). This resulted in a significant reduction in food intake over the 72h treatment period in hamsters in LD (~60%), and a smaller reduction in food intake in SD (~40%). In LD, treatment with H7 resulted in a significant decrease (~50%) in DIO2 mRNA expression in the tanycyte layer of the medial basal hypothalamus. In SD, endogenous DIO2 expression was significantly lower than in LD as expected but H7 treatment did not significantly decrease its expression. In summary, a monoclonal antibody specifically targeting the FGFR1c isoform reduces food intake and body weight in a natural model of adiposity. These effects are far more substantial in hamster maintained in their LD fat state and appear to be associated with the reduction in mRNA expression of the deiodinase enzyme, DIO2.

Supported by Eli Lilly and a BBSRC studentship.
Decreased neurogenesis in the Dentate Gyrus following sensory non‐normative overstimulation.
Authors: Ramirez Julian Sergej Benedikt , Christakis Dimitri A , Hodge Rebecca Dawn , Hevner Robert F , Smith Audrey Frances , Ramirez Tamina Keira‐Malin , Burgos Maria Florencia , Ramirez Jan Marino
Published: June 2021

Human infants are increasingly exposed to excessive fast‐paced television viewing leading to sensory overstimulation, which may result in significant deficits in cognition and attention. We tested this hypothesis in a mouse model in which young mice (P10) were exposed to audio and visual overstimulation for six hours per day for a total of 42 days. Overstimulation had detrimental effects resulting in diminished cognition, hyperactivity and increased risk taking (Christakis et al. 2012). Prior studies have shown that exposing mice to an enriched environment (EE) results in improved learning and memory and increased neurogenesis in the dentate gyrus. Here we demonstrate, that sensory overstimulation had the opposite effect and resulted in diminished learning abilities and decreased neurogenesis within the dentate gyrus. Decreased neurogenesis was demonstrated by staining brains of overstimulated and control mice with the antigen KI67 (Ki67), T‐Box Brain Protein 2 (Tbr2), SRY (sex determining region Y)‐box 2 (Sox2) and Double Cortin (DCX). We conclude that excessive non‐ normative stimulation has significant detrimental effects on neurogenesis. Interestingly, this effect was only seen when overstimulating mice as neonates, but not as adults.
Sensitivity of forearm critical power to acute manipulation of perfusion pressure
Authors: Kellawan Mikhail , Bentley Robert F , Walsh Jeremy J , Moynes Jaclyn S , Tschakovsky Michael E
Published: June 2021

PURPOSE

We tested the hypothesis that manipulating perfusion pressure (PP) impacts forearm critical power (fCP).

METHODS

9 healthy young (23 ± 2.6 yrs) males completed 10 min fCP tests in each of arm above (A) and below (B) heart level (forearm PP A < B by ~30 mmHg). fCP (average of force impulse in last 30 s of test), forearm blood flow (FBF; echo and Doppler ultrasound), arterial pressure (MAP; finger photoplethysmography), O2 consumption (VO2; venous blood samples, Fick eqn) were measured during exercise.

RESULTS

mean ± SD. Responders (all with compromised fCP in A vs. B; 21 ± 7 vs. 30 ± 6 kg·s, p=0.01) and non‐responders (no compromise to fCP in A vs. B; 29 ± 17 vs. 27 ± 16 kg·s, P=0.14) were identified. Responders exhibited O2D compromise in A vs. B (164 ± 60 vs. 178 ± 65 ml O2/min, p=0.04), and all had lower VO2 in A vs. B but this was not statistically significant (VO2 88 ± 30 ml/min vs. 104 ± 40 ml/min, p=0.12). Non‐responders had no compromise to O2D in A vs. B (153 ± 26 vs. 164 ± 28 ml O2/min, p=0.53), nor any compromise to VO2 (99 ± 21 ml/min vs. 106 ± 28 ml/min, p=0.58). No clear pattern regarding pressor or vasodilatory compensation to protect O2D was found (Responders A vs. B, ΔFVC p=0.01, ΔMAP p=0.12; Non‐responders A vs. B ΔFVC p=0.22, ΔMAP p=0.37).

CONCLUSIONS

Reductions in perfusion pressure can reduce forearm critical power in individuals who cannot defend O2D. These data highlight the importance of O2D to fCP. NSERC
Lower potassium intake is associated with increased wave reflection in young healthy males
Authors: Lennon‐Edwards Shannon , Schellhardt Taylor , Allman Brittany , Farquhar William B , Edwards David G
Published: June 2021

Increased potassium intake has been shown to lower blood pressure (BP) even in the presence of high sodium consumption however the role of dietary potassium on vascular function has received less attention. The objective of this study was to evaluate the relationship between habitual intake of sodium (Na) and potassium (K) and measures of arterial stiffness and wave reflection. 20 healthy males (24±0.7 yrs; systolic BP 121±3; diastolic BP 64±2 mmHg) recorded their dietary intake for 3 days and collected their 24‐hr urine on the 3rd day. Carotid‐femoral pulse wave velocity (PWV) and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) were performed. Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform. Subjects consumed an average of 2,492 kcals, 4,212 mg Na, and 2,967 mg of K. Average urinary Na/K excretion ratio was 2.69±0.3. An inverse relationship between AI and K excretion was found (r= −0.3122; p<0.001) while no relationship was noted with Na excretion (r= − 0.005; p>;0.05). AI positively correlated with the Na/K excretion ratio (r= 0.153; p<0.05). PWV did not correlate with either nutrient or the Na/K excretion ratio (p>;0.05). These data suggest that lower potassium intakes are associated with stiffer arteries in young healthy males. Supported by R01 HL 104106.
Disturbed flow increases caveolae‐mediated oxLDL uptake in endothelial cells
Authors: LeMaster Elizabeth , Sun Shan , Shinin Vasily , Eddington David , Cho Michael , Minshall Richard , Levitan Irena
Published: June 2021

Oxidized low density lipoprotein (oxLDL) is a major risk factor in the development of atherosclerotic plaques, which form at vessel bifurcations and under recirculating (disturbed) flow patterns. It is also known that oxLDL‐induced endothelial injury is the first step in plaque formation. In this study, we tested the impact of different hemodynamic conditions on endothelial cell (EC) uptake of oxLDL. ECs were exposed to shear stress (SS): laminar and oscillatory SS were generated using a parallel plate flow chamber and recirculating SS was created by designing and microfabricating a flow channel with a single step occlusion. We show that ECs exposed to recirculating flow had greater oxLDL uptake compared to ECs in laminar regions. Surprisingly, oscillatory flow inhibited rather than facilitated oxLDL uptake into ECs as compared to laminar flow. Furthermore, we show that EC uptake of oxLDL was significantly reduced by knocking out caveolin‐1, the major protein of caveolae. This indicates that caveolae play a major role in oxLDL uptake into ECs and is consistent with studies showing that Cav‐1‐KO mice do not develop atherosclerosis. Finally, since our previous studies show that exposing ECs to oxLDL increases EC stiffness in vitro, we compared EC stiffness of intact vessels in WT and ApoE KO mice. Surprisingly, ECs in ApoE KO mice are softer than in WT mice. Further studies are required to investigate this phenomenon.
GENE EXPRESSION PROFILING IN THE RAT INFARCTED HEART IN RESPONSE TO ANTIOXIDANT TREATMENT
Authors: Zhao wenyuan , Zhao Tieqiang , Chen Yuanjian , Qu Yanhua , Gerling Ivan C , Weber Karl T , Sun Yao
Published: June 2021

Cardiac oxidative stress is developed following myocardial infarction (MI). The influence of reactive oxygen species (ROS) on gene expression profiling and molecular pathways in the infarcted myocardium was explored. Rats with MI were treated with or without combined antioxidants, tempol and apocynin (each 120mg/kg/day) for 1 week. The increase of malondialdehyde in the infarcted myocardium was significantly suppressed by antioxidants. Microarray assay showed that antioxidants significantly altered the expression of 159 genes compared to untreated rats with MI. Ingenuity pathway (IPA) analysis indicated that multiple pathway networks were affected by antioxidants, including those related to cellular movement, growth and proliferation, tissue development, cell death, and inflammatory/fibrotic responses. IPA further identified that these changes were primarily related to NF¥êB, p38 MAPK, and ERK1/2 pathways. Several hub genes, including actin, integrin, ICAM/VCAM, TGF©¬ and TNF were identified in the associated gene networks. Our study indicates that ROS regulate various molecular and cellular actions related to cardiac repair/remodeling through multiple gene networks.
The Passive Mechanical Environment Alters the Phenotype of Cardiac Fibroblasts
Authors: Galantowicz Maarten , West T. Aaron , Zhang Xiaojin , Childers Rachel C. , Gooch Keith J. , Weibel John C. , Cismowski Mary J. , Lucchesi Pamela A.
Published: June 2021

While the active hemodynamic environment is a key contributor to LV remodeling in heart failure (HF), recent work suggests an important role of the passive mechanical environment (e.g. substrate stiffness) in controlling the phenotype of cardiac cells, including cardiac fibroblasts. (CFs). CFs are primary modulators of ECM remodeling during HF. To explore the role of the active and passive mechanical environments on CF phenotype, CFs were isolated from Sprague‐Dawley rats and cultured on stiff (E = 3,240 MPa) or elastomer silicone (E=1,100 kPa) substrates. Flexible substrates were kept stationary or exposed to 0–5% biaxial strain at 1 Hz for 24 hr. Smooth muscle actin (SMA), a myofibroblast phenotype marker, and β1‐integrin were assessed by Western blot analysis. The protein expression of SMA and β1‐integrin were significantly decreased in CFs cultured on elastomer silicone substrates with or without cyclic biaxial stretch, as compared to CFs cultured on stiff substrates (both P<0.05). There was not a significant difference between stretched and non‐stretched CFs cultured on silicone substrates (P>;0.05). These results indicate that the passive mechanical environment may alter CF phenotype and cell‐matrix communication, which may have strong implications in the pathophysiology of HF. Support: NIH R01HL056046 (PAL).
Extrarenal citrulline utilization in mice
Authors: Marini Juan C , Didelija Inka C
Published: June 2021

Citrulline (Cit) is an amino acid produced in the gut and used by the kidney, in what is called the intestinal‐renal axis of arginine (Arg) synthesis. However, other sites of Cit utilization may exist given the widespread presence of enzymes needed to carry out this process. To test the hypothesis that the disposal of Cit can take place in extrarenal tissue, studies in chronic (conscious) and acute (anesthetized) nephrectomized mice were conducted. (ureido)[15N]‐citrulline and [15N4] arginine were utilized to determine the rate of Cit appearance (RaCit) and disposal, and the rate of conversion of Cit into Arg (RcCA). Whereas Cit concentration correlated with the extent of kidney ablation (control, 1/2 and 5/6 nephrectomy, 21, 38 and 111 μmol/L, resp.), RaCit remained unchanged (121 μmol•kg−1•h−1). RcCA (108, 75 and 54 μmol•kg−1•h−1) and Cit clearance (103, 56, 30 mL•kg−1•h−1), however, decreased. Acute kidney ligation reduced Cit disposal rate (0.018 vs. 0.031/min, LIG and SHAM resp.) which resulted in a 74% and 93% increase in Cit half life and mean residence time. SHAM resulted in a rapid conversion of Cit into Arg, whereas LIG showed a slow but sustained process, suggesting an extrarenal source for plasma arginine. This source accounted for 25% of the plasma arginine produced. Together these data demonstrate that extrarenal sources for citrulline utilization exist, ant that some of them contribute to plasma arginine.
Mechanical Tissue Resuscitation (MTR) reduces myocardial tissue injury following myocardial ischemia‐reperfusion (MI/R)
Authors: Jordan James E. , Mays Jennifer J. , Shelton Julie E. , Thompson Edreca A. , Bryant Allyson K. , Lane Magan R. , Morykwas Michael J.
Published: June 2021

Background

Reperfusion following an ischemic myocardial event increases cell death by activation of inflammatory processes. Reducing reperfusion injury may improve morbidity and mortality following AMI. We have previously shown MTR to reduce infarct size following MI/R. Here, we determine the effects of MTR on apoptosis and edema using a novel, bio‐absorbable patch.

Methods

A left, anterior free‐wall ischemic lesion (80 minutes) was created using reversible tourniquets in swine. Animals were randomized to receive either no treatment (Control) or MTR (− 50mmHg) using a bio‐absorbable patch at reperfusion. Following 3 hours of reperfusion, infarct size, apoptosis and edema were determined.

Results

While both groups had similar areas at risk (AAR/LV, 13.2 ± 0.7% and 14.8 ± 0.5%; p=.09), infarct size (AN/AAR) was significantly reduced in MTR‐treated animals (16.8±2.8%, p <.05) compared to controls (26.4±2.8%). This myocardial protection was accompanied by a reduction in epicardial apoptosis (7.7 ± 1.9% vs. 29.3 ± 7.7% TUNEL positive cells). MTR also reduced interstitial space in the endocardium by 53% and in the epicardium by 34%.

Conclusions

MTR applied directly over the infarcted area of the heart by means of a bio‐absorbable patch results in tissue preservation which may be the result of changes in apoptosis and edema formation. These data suggest that MTR could be an appropriate therapeutic approach to decrease myocyte death following a myocardial infarction.
Ga13 Targeting of VE‐cadherin Mediates Disassembly of Adherens Junctions and Endothelial Permeability
Authors: Gong Haixia , Gao Xiaopei , Siddiqui M Rizwan , Garcia Alexander , Bonini Marcelo , Vogel Stephen M , Malik Asrar B.
Published: June 2021

The heterotrimeric G protein α unit Gα13 transmits signals from G protein coupled receptors (GPCRs) to effectors to regulate cell spreading, differentiation, migration, and cell polarity. Both conventional and endothelial cell‐specific Gα13 gene knockouts are embryonically lethal because of impaired vasculogenesis. Here we describe a new pro‐inflammatory function of Gα13 through its displacement from the GPCR protease‐activated receptor 1 (PAR1) to the endothelial adherens junction (AJ) protein VE‐cadherin. H2O2 production induced by multiple mediators (thrombin, LPS or TNFα) induced a shift in Gα13 binding to VE‐cadherin and disassembly of AJs. Gα13/VE‐cadherin interaction activated c‐Src resulting in phosphorylation of VE‐cadherin at Tyr 658, the p120‐ catenin binding site responsible for VE‐cadherin endocytosis from the membrane. Preventing Gα13/VE‐cadherin interaction by Cre recombinase‐mediated Gα13 knockout in mice or an interfering myristoylated peptide derived from VE‐cadherin, inhibited AJ disruption and inflammatory response to sepsis. These studies establish a crucial Gα13 switch mechanism activated by H2O2 generation that mediates Gα13 binding to VE‐cadherin and thereby disrupts AJ integrity. Therefore, blocking Gα13 translocation and Gα13/VE‐cadherin interaction represents a potential anti‐inflammatory target.
Sex‐differences in the effects of isometric handgrip training on resting blood pressure and resistance vessel function
Authors: Badrov Mark B. , Freeman Shane R. , Millar Philip J. , McGowan Cheri L.
Published: June 2021

Isometric handgrip (IHG) training lowers resting blood pressure (BP) in normotensive and hypertensive populations, yet potential sex‐differences and mechanisms associated with the hypotensive response remain unclear. We studied, in normotensives, sex‐differences in the effects of IHG training on resting BP and resistance vessel function (RVF), a hypothesized mechanism of post‐training BP reduction. Resting BP (brachial artery oscillometry) and RVF (venous strain gauge plethysmography with reactive hyperaemia) were assessed in 12 females (23 ± 4 yrs; mean ± SD) and 9 males (21 ± 2 yrs), pre‐ and post‐ 8 wks of IHG training (Four, 2 min unilateral contractions at 30% of maximal effort, 3 d•wk−1). IHG training reduced resting systolic BP in both females and males (Females: 94 ± 6 to 88 ± 5 mmHg; Males: 105 ± 10 to 96 ± 7 mmHg, all P < 0.05), but the magnitude of BP reduction was similar between sexes (P >; 0.05). Diastolic BP remained unchanged in both females and males (Females: 57 ± 7 to 54 ± 6 mmHg; Males: 57 ± 5 to 56 ± 5 mmHg, all P >; 0.05). In each sex, systolic BP reductions occurred concomitant to increases in forearm reactive hyperaemic blood flow (Females: 26 ± 7 to 36 ± 9 mL•min−1•100 mL−1; Males: 35 ± 11 to 38 ± 13 mL•min−1•100 mL−1, all P < 0.05). In conclusion, IHG training effectively lowers resting BP in both females and males, and improved RVF may mediate the post‐training BP response in both sexes. Supported by University of Windsor.
Modeling exercise effects on cardiovascular fitness using STELLA
Authors: Sanders Andrew C. , Davidson Robert T.
Published: June 2021

As physical and metabolic fitness continues to play a large role in the development of chronic disease, it is desirable to know precisely how exercise and workout routines may affect measures of cardiovascular fitness. Likewise, it would be helpful to be able to quantitatively design exercise routines to optimize fitness outcomes for an individual. Using STELLA modeling software we used the individual physical fitness level determined using standardized tests and compared to published norms, combined with published dose‐response data from fitness test‐specific exercise studies to develop a mathematical model of human fitness level gains. The model was validated against two independent sets of published data that measured change in VO2max following exercise interventions. Predicted values for VO2max had standard errors of 3.99% and 4.39%, respectively, when the independent study parameters were entered into the model. This model may best be used as a tool to calculate how specific interventions might impact cardiovascular fitness or be used to quantitatively develop specific fitness routines to maximize or optimize cardiovascular fitness.
Overall stress response is reduced in U.S. Marines following infantry training
Authors: Kelly Karen , Jensen Andrew , Niederberger Brenda , Congalton Robert , Jaworski Rebecca
Published: June 2021

This study measured changes in stress proteins during basic U.S. Marine infantry training. Blood samples were obtained at day 0, 12, 28 and 40 at rest and post‐hikes at various distances. Results show that TNFá levels were attenuated (TNFá, pre‐5k: 3.8±0.5, post‐5k: 5.5±0.8, P =0.0005; pre‐20k: 4.3±0.9, post‐20k:4.9±0.9, P=0.39 pg/ml); IL‐6 increased from pre‐ to post hike for both the 5k and 20k (P<0.0001); however there were no differences between the 5k and 20k (蜐5k:3.5±0.8; 蜐20k:3.3±0.2, P>;0.05).There was a trend towards a decrease in CRP (P=0.07). Cortisol showed a linear decline from day 0–28 and plateau during the final week (baseline: 75.6 ±5.5, pre‐5k: 57.2±6.7, pre‐15k: 38.2±3.9, pre‐20k:42.0±3.7; P<0.001). These results suggest that despite an increase in hike duration and intensity was an overall reduced stress response indicating that exercise training can mitigate classical inflammatory protein response. The rise in IL‐6 following the 20k, independent of change in TNFá, suggests that IL‐6 is acting to regulate metabolism rather than inflammation. The lack of rise in IL‐6 between the 5k and 20k is indicative of an increased reliance on lipid metabolism rather than glucose, which IL‐6 is known to regulate. In summary, despite the increased physical stress over the course of infantry training, physiological adaptations occur to mitigate inflammation and regulate metabolism.
Effect of Unilateral E‐Stim on Strength in a Contralateral Untrained Limb After Bilateral Strength Training
Authors: LoRusso Stephen , Barr Nathaniel , Hanik William , Hazen Joshua , Strittmatter Amanda , Tocco Tatum
Published: June 2021

Unilateral strength training or electrical stimulation increases strength in an untrained, contralateral limb. This cross education effect is similar to conventional training. We have shown reduced strength loss in a contralateral untrained limb with unilateral strength training after 4 weeks of bilateral leg extension training.

Methods

In a pre‐and post‐test design, 18 subjects, aged 18–35, not engaged in structured strength training for 3 months, were randomly assigned to a unilateral strength training (U), e‐stim training (E), or control group(C). All subjects underwent 4 weeks of bilateral leg extension training, then for 4 weeks, either stopped training, or trained the right limb with strength training or e‐stim. A pre‐training, 4 week post‐training and final unilateral 1 RM for leg extension was obtained.

Results

After 4 weeks of bilateral training, unilateral 1 RM strength significantly increased (left leg p=0.001; right leg p=0.000). However, during the final 4 weeks, all subjects lost strength in the trained and untrained limbs. The percent change in the untrained and trained limbs respectively were: Group E −4.23%; −1.20%; Group U −6.05%; −0.78% and Group C −8.47%; −6.55%.

Conclusion

At these training loads, neither unilateral strength training or e‐stim had a significant effect on the trained or untrained limb, and therefore were unable to prevent strength loss in either limb.
Low volume high intensity training improves insulin sensitivity but reduces aerobic power in trained middle‐aged runners
Authors: Winding Kamilla , Hansen Louise Seier , Knudsen Trine Alma , Hellsten Ylva , Mortensen Stefan Peter , Pedersen Bente Klarlund
Published: June 2021

Objective

To investigate if high intensity interval training (HIIT) improves performance and insulin sensitivity in trained middleaged runners.

Methods

Sixteen male runners (47±2 years and VO2max of 50±2 mlO2/kg/min) were randomly assigned to 6 weeks of HIIT (6–10 one minute intervals at 100% maximal running speed, 3 times per week) or habitual training (CON). HIIT replaced ~25–44% of the subjects’ aerobic based training, reducing running volume by 26.2% compared to before the experiment. Before and after the training period, performance was tested on the treadmill and insulin sensitivity was measured by oral glucose tolerance test using the Matsuda Index. Resting muscle biopsies were also obtained from the m. vastus lateralis.

Results

HIIT improved the lactate threshold (P<0.001) and the velocity associated with VO2max (P<0.01) whereas they were unchanged in CON. HIIT training increased CD31 content (P<0.05), whereas VO2max (P<0.001) and the content of oxidative enzymes was reduced (P<0.05). The monocarboxylate transporter 4 and the Na+/H+ exchanger 1 were unchanged. Insulin sensitivity increased by 23±11% in the HIIT group (P<0.05), and was higher than the CON group after training (P<0.05).

Conclusion

In middle‐aged runners, HIIT improves insulin sensitivity, but impairs aerobic power and oxidative enzyme content.
Perinatal Sulfur Dioxide Exposure Alters Brainstem Parasympathetic Control of Heart Rate
Authors: Woerman Amanda L , Mendelowitz David
Published: June 2021

Sulfur dioxide (SO2) is an air pollutant that induces adverse cardiorespiratory health effects, including MI and tachycardia, and impedes neonatal development. We developed an animal model enabling characterization of in vivo alterations in heart rate (HR) and cellular changes in brainstem neurons that control HR after perinatal SO2 exposure. Pregnant Sprague Dawley rats were exposed to 5 ppm SO2 for 1 h daily throughout gestation and 6 days postnatal (P6). ECGs were recorded from pups at P5 to examine changes in basal HR elicited by perinatal SO2 exposure. In vitro studies used whole‐cell patch‐clamp electrophysiology to examine changes in transmission to cardiac vagal neurons (CVNs) within the nucleus ambiguus upon SO2 exposure using a preparation retaining fictive inspiratory activity. SO2 exposure increased HR, indicative of a loss of parasympathetic drive. Neither spontaneous nor inspiratory‐related GABAergic or glycinergic transmission to CVNs was altered by SO2 exposure, however glutamatergic transmission was decreased by 50%. This diminished excitatory transmission was TTX‐sensitive, indicating SO2 exposure impairs the activity of preceding glutamatergic neurons that synapse upon CVNs. Diminished glutamatergic, but unaltered inhibitory transmission to CVNs provides a mechanism for the observed SO2‐induced tachycardia via a loss of brainstem parasympathetic activity to the heart.

Funded by NIH grants HL49965, HL59895, & HL72006 to DM, & GW Institute for Sustainability Research, Education, & Policy Research Award to ALW.
Endogenous hydrogen sulfide in the rostral ventrolateral medulla (RVLM) mediates ventilatory response induced by hypoxia.
Authors: Donatti Alberto Ferreira , Kwiatkoski Marcelo , Soriano Renato Nery , Carnio Evelin Capelari , Branco Luiz Guilherme Siqueira
Published: June 2021

We investigated the involvement of hydrogen sulfide (H2S), in the RVLM, in the ventilator response of hypoxia. Wistar rats were implanted with a stainless steel guide cannula above the RVLM region. The animals were microinjected with a CBS inhibitor (amino‐oxyacetate ‐ AOA) in two different concentration, 20 fmol/2 μl and 200 fmol/2 μl or phosphate buffer (PH 7.4) (2 μl) as vehicle. After the microinjection, ventilation of the animals was measured during 60 min in normoxia or hypoxia. During normoxia, microinjection of AOA did not change ventilation compared with PBS (p>;0.05). When microinjected with AOA 20 fmol/2 μl and exposed to hypoxia, the rats showed a significant increase (p<0.05) in ventilation (1506±169 ml/kg/min) compared with PBS (1279.78±90 ml/kg/min). When microinjected AOA 200 fmol/2 μl and exposed to hypoxia, the rats showed an increased (p<0.05) frequency (143.4±7.7 breaths/min) compared with PBS (114.9±3.8 breaths/min). The present results show that endogenous H2S plays an important role in modulating ventilatory response to hypoxia in the RVLM. Financial support: FAPESP, CAPES, CNPq (Brazil).
Short‐term sustained hypoxia affects synaptic transmission in the nucleus tractus solitarius neurons of juvenile rats
Authors: Accorsi‐Mendonça Daniela , Almado Carlos E.L. , Machado Benedito H.
Published: June 2021

In the present study we evaluated the effects of a short‐term sustained hypoxia [(SH) 24 hours ‐ 10% O2] on intrinsic properties and synaptic transmission of nucleus tractus solitary (NTS) neurons of juvenile Wistar rats (P21). After 24 hours inside hypoxic or normoxic chambers rats were anesthetized, the brains removed and brainstems sliced. Intrinsic properties and excitatory currents of NTS neurons were recorded using whole‐cell patch clamp. SH did not change the resting membrane potential (control: −78.7 ± 2.4 mV n=15; SH: −72.3 ± 3.7 mV n=15), input resistance (control: 1.4 ± 0.4 G Ohm n=8; SH: 1.4 ± 0.4 G Ohm n=9) or capacitance of neurons (control: 14.2 ± 0.9 pF n=17; SH: 12.4 ± 0.8 pF n=15), indicating that SH does not change the intrinsic properties of NTS neurons. However, it was observed an increase in frequency of spontaneous currents (control: 3.6 ± 0.4 Hz n=18; SH: 7.1 ± 1.5 Hz n=15) and in peak amplitude of evoked currents (control: −289 ± 51 pA n=15; SH: −472 ± 64 pA n=15). Moreover, after a train of 5 stimuli, NTS neurons from SH group presented higher depression in glutamatergic events (relative amplitude of evoked currents; control: 100, 44, 34, 32 and 28%; SH: 100, 40, 28, 22 and 17%, *p<0.001, n=15), suggesting that SH affects the vesicular release probability. The data show that short‐term SH increases the spontaneous and evoked neurotransmitter release in the NTS neurons, which may explain, at least in part, the autonomic and respiratory changes observed in this experimental model.

Financial support: FAPESP and CNPq.
Intermittent Hypoxia Induces Leptin Signalling in the Carotid Body
Authors: Ciriello John , Messenger Scott A.
Published: June 2021

Glomus cells in the carotid body are responsible for detecting changes in blood PO2. These glomus cells have recently been found to express leptin receptors and are activated by intermittent hypoxia (IH) and systemic leptin injections, although the function of leptin within the carotid body remains unknown. The present study was done to investigate whether IH activates leptin signalling pathways within leptin‐expressing carotid body glomus cells. Rats were subjected to IH (120s normoxia, 80s hypoxia for 8 h) or normoxia (8h). Exposure to IH increased plasma leptin levels almost 6‐fold compared to normoxic controls. Additionally, IH was found to increase leptin, ERK1/2 and Fra‐1/2 immunoreactivity within glomus cells. Systemic leptin injections evoked similar effects on leptin, ERK1/2 and Fra‐1/2 immunoreactivity within the glomus cells. Furthermore, using Western blot analysis, IH was found to increase protein expression of leptin, the short form of the leptin receptor (Ob‐R100 kDa), pSTAT3 and SOCS3. On the other hand, IH induced a decrease in Ob‐Rb protein expression. Taken together, these data suggest that the increased levels of leptin within the circulation and those within the glomus cells induced by IH may function within the carotid body to alter the sensitivity of chemoreceptors to hypoxic stimuli.

Supported by Heart and Stroke Foundation of Ontario
Plasticity in the Microvasculature of Conditioned Weight Lifters After Acute High Pressure Stress
Authors: Durand Matthew J. , Phillips Shane A. , Gutterman David D.
Published: June 2021

Transient hypertension evoked by exercise impairs endothelial function in sedentary (SED) subjects but not in weight lifters (WL). We hypothesized that nitric oxide (NO) mediated vasodilation is preserved in microvessels from WL after exposure to high pressure compared to microvessels from SED subjects. Adipose arterioles were obtained from volunteers by gluteal biopsy, cannulated for videomicroscopy in a heated chamber filled with Krebs solution, pressurized to 60 mmHg, constricted with endothelin‐1, and dilation to acetylcholine (Ach) was assessed in the presence or absence of L‐NAME, rotenone, PEG‐catalase or Mito‐TEMPO. ACh‐induced dilation was measured again after raising intraluminal pressure to 150 mmHg for 30 minutes. After exposure to high pressure, microvessels from WL maintained dilation to Ach (before: 92±1.4%; after: 89±1.3%), but dilation in SED was reduced (before: 97±2.9%; after: 39±9.2%). At 60 mmHg of pressure, L‐NAME reduced dilation in WL while PEG‐catalase did not. After exposure to 150 mmHg, PEG‐catalase significantly reduced dilation, while L‐NAME had no effect. Both rotenone and Mito‐TEMPO also inhibited the H2O2‐mediated dilator response after high pressure. These results indicate that after expose to high pressure in WL, dilation to ACh is maintained by switching from an NO‐ mediated to a H2O2‐mediated dilation. The mitochondria play a critical role in this adaptive process.
Isoflurane stimulates firing frequency and masks chemosensitivity of CO2‐inhibited GABAergic neurons in situ
Authors: Johansen Sara Louise , Iceman Kimberly E. , Richerson George B. , Harris Michael B.
Published: June 2021

Anesthesia mechanisms are poorly understood, despite their importance in clinical medicine and potential to confound experimental results. Postsynaptic effects such as γ‐aminobutyric acid (GABA) inhibition through GABAA receptors are recognized, but presynaptic mechanisms are largely undescribed. We have shown that isoflurane inhibits and masks chemosensitivity of CO2‐stimulated serotonin synthesizing neurons in situ, and we hypothesize this effect is dose‐dependent. We further hypothesize that isoflurane stimulates and masks sensitivity of CO2‐inhibited GABAergic neurons. Before and during isoflurane exposure, in situ raphé extracellular recordings were made during hypercapnia. Juxtacellular labeling and immunohistochemistry identified neuron phenotype. Results show that isoflurane dose‐dependently inhibits serotonergic neurons, increases firing frequency of GABAergic neurons and masks chemosensitivity. Isoflurane‐induced increases in GABAergic neuron firing may contribute to central inhibition characteristic of anesthesia. Prevention of CO2‐sensitive inhibition of GABAergic neurons and postsynaptic disinhibition may contribute to attenuated hypercapnic responses during anesthesia. These conclusions suggest two presynaptic sites of anesthetic action that may be critical to mechanisms of anesthesia. NIH 2U54NS041069–06A1, IAB Fellowship, Alaska INBRE P20GM103395.
Purinergic signaling in the retrotrapezoid nucleus (RTN) contributes to central and peripheral chemoreflexes by divergent mechansims
Authors: Moreira Thiago S , Sobrinho Cleyton R , Wenker Ian C , Mulkey Daniel K , Takakura Ana C
Published: June 2021

Evidence suggests that purinergic signaling in the retrotrapezoid nucleus (RTN) can influence both respiratory and sympathetic activity. Here we evaluate the extent to which purinergic signaling contributes to central and peripheral chemoreception integration at the level of the RTN in vivo. Mean arterial pressure (MAP) and phrenic nerve activity (PNA) were recorded in urethane‐anaesthetized, vagotomized and artificial ventilated male Wistar rats (n = 6–7/group). Bilateral RTN injections of a non‐specific P2‐receptor blocker (PPADS) decreased pressor (8 ± 2 mmHg, vs. saline: 22 ± 4 mmHg) and respiratory (PNA amplitude = 62 ± 3%, vs. saline: 101 ± 5% and PNA frequency = 77 ± 3%, vs. saline: 101 ± 5%) responses to 10% CO2. Conversely, bilateral RTN injections of MRS2179 (P2Y1 receptor antagonist) attenuated cardiorespiratory responses to peripheral chemoreceptor activation, but did not affect CO2‐responsivness. Further, 63% of BDA‐labeled NTS terminals in the RTN are immunoreactive for vesicular glutamate transporter‐2 (VGLUT2) and vesicular nucleotide transporter (VNUT) but only 5% contained glutamic acid decarboxylase‐67 (GAD67). These data indicate that purinergic signaling in the RTN contributes to central and peripheral chemoreception by different, but potentially interactive, mechanisms
Carotid Body Denervation Attenuates Oscillations in Respiratory Rate and Sympathetic Nerve Activity, and Decreases Apnea/Hypopnea Index in Congestive Heart Failure
Authors: Marcus Noah J , Del Rio Rodrigo , Schultz Harold D
Published: June 2021

Cheyne‐Stokes respiration is associated with increased morbidity and mortality in patients with congestive heart failure(CHF) and commonly coincides with high chemosensitivity. We hypothesized that incidence of disordered breathing patterns would be increased in a rabbit model of pacing‐induced CHF, and that denervation of the carotid body chemoreceptors (CBD) would attenuate these changes. Plethysmography was used to measure resting breathing pattern and the ventilatory responses to hypoxia (Hx) and hypercapnia (Hc). Sympathetic nerve activity was measured directly from the renal nerves (RSNA) of conscious animals. Resting respiratory pattern was quantified by an apnea‐hypopnea index (AHI) and a respiratory oscillation index. RSNA and ventilatory responses to Hx were augmented in CHF, and nearly abolished by CBD. CBD also resulted in a 40% reduction in Hc response. CHF resulted in increased incidence of oscillations in respiratory rate that were accompanied by surges in blood pressure, heart rate, and RSNA. The incidence of these oscillations was reduced after CBD (pre‐pace 26±3/h, CHF 48±5/h, CHF‐CBD 13±7/h). The AHI was increased with CHF and this increase was attenuated after CBD (pre‐pace 9±2, CHF 17±3, CHF‐CBD 5±1). Our findings suggest that CB denervation may be an effective treatment to reduce respiratory instability in CHF patients.

Funding: NIH 1F32HL108592–01A1 & Coridea NC1.
Can haptoglobin attenuate hemoglobin‐induced vascular damage?
Authors: Alonso Yanaira , Lisk Christina , Irwin David
Published: June 2021

Hemolytic diseases and infections can lead to intravascular hemolysis, which causes increased plasma hemoglobin (Hb) concentration. Over time, this “cell free Hb” is toxic to the blood vessels, exerting oxidative damage, nitric oxide (NO) scavenging, or inflammatory responses within the vasculature. The exposure of increased Hb on the lung tissue can lead to pulmonary hypertension (PH), which is high blood pressure in the pulmonary arteries due to changes in arterial wall. Haptaglobin is an acute phase protein responsible for binding and clearance of Hb. We hypothesized that haptoglobin (Hp) can attenuate PH secondarily to vascular hemoglobin exposure. To test our hypothesis, Hb was chronically administered to rats at physiologically relevant concentrations as observed in the sickle cell disease (SCD) (0.2 μmole/day) for 5 weeks. To further mimic the SCD process, rats were placed in hypobaric hypoxic chambers (~17,000 ft). Animals were divided into 4 groups; (1) Control (sham), (2) Hb infusion, (3) Hp injections (biweekly), and (4) Hb: Hp (chronically infused with Hb treated biweekly with Hp). At the end of the 5 weeks, we evaluated pulmonary blood pressure, cardiac output, and pulmonary vascular wall thickness. Additionally, lung analysis for indicators of endothelial nitric oxide synthase (eNOS) and intercellular adhesion molecule 1 (ICAM‐1) expression were performed. Preliminary data demonstrates that groups infused with haptoglobin had lower pulmonary blood pressure, decreased vessel wall thickness, and decreased ICAM‐1 expression. We observed no difference in eNOS expression between groups. This suggests that Hb induced inflammation may be attenuated by Hp.
Detecting cell adhesion molecules in intact lung using quantum dot conjugates targeted to endothelial cells
Authors: Orndorff Rebecca L. , Hong Nan Kang , Zern Blaine J. , Yu Kevin , Debolt Kristine , Muzykantov Vladimir R. , Huang Shaohui , Fisher Aron B. , Chatterjee Shampa
Published: June 2021

Quantum dots (QD) coupled with fluorescence imaging techniques are a powerful tool for detecting proteins in vivo. Here we used dual QD labeling to detect cellular adhesion molecules, CAM (endothelial marker, PECAM and vascular cell adhesion molecule, VCAM) expression in a LPS model of lung inflammation. QDs were functionalized via an adaptor protein and linked to anti‐PECAM and anti‐VCAM Abs to create QD655‐PECAM (QDP) and QD525‐VCAM (QDV), respectively. We established probe specificity in vitro in a PECAM expressing cell line and in LPS treated endothelial cells (for VCAM). For in situ experiments, mice lungs were removed at 24h after LPS instillation, and perfused with medium containing QDV and QDP. For in vivo lung studies, QDs were injected into the jugular vein at 24h after LPS treatment and lungs were removed and processed after overnight fixation. Imaged sections from both studies showed that LPS treated mice had 8–10 fold higher QDV signal, compared to naïve lungs, which significantly colocalized with QDP, indicating increased VCAM expression in pulmonary endothelium. Thus, QD labeling for intravital microscopy will be useful for detection and localization of proteins in pulmonary tissue.
Attenuating complex I activity decreases p66shc phosphorylation and translocation to mitochondria during cardiac ischemia reperfusion injury
Authors: Yang Meiying , Stowe David F , Heisner James S , Camara Amadou K.S.
Published: June 2021

Mitochondrial reactive oxygen species (mROS), produced via complexes I and III electron leak, play a critical role in cardiac ischemia (I) and reperfusion (R) injury. p66shc, a splice variant of the ShcA adaptor protein family, enhances mROS by oxidizing reduced cyt c to yield H2O2. p66shc ablation protects against IR injury by decreasing mROS. It is not known if blocking complex I electron transfer impacts p66shc activation during IR. To test this, isolated guinea pig hearts were buffer perfused and subjected to 5, 10, 20 or 35 min I and 20 min R ± amobarbital (AMB), a complex I blocker. Levels of p66shcin mitochondria (mitop66shc) and phosphorylation of p66shc at serine36(phoSer36) were measured by Western blot and immunoprecipitation. We found that phoSer36 and mitop66shc increased during reperfusion after I 20, 35, but not during ischemia. Moreover, I 20 or I 35+R 20, but not I 5 or I 10+R 20 increased phoSer36 and mitop66shc. AMB given 1 min before I reduced phoSer36 and mitop66shc induced by I 20 or I 30+R 20, but not I 35+R 20. Low levels of phoSer36 and mitop66shc were associated with better recovery during R. Our results show that p66shc was activated by IR. Shorter I time or attenuating complex I decreased activation of p66shc. AMB reduces electron transfer during IR and thereby decrease reduction of cyt c, a p66shc substrate mediated mROS production, as a possible mechanism to improve function during reperfusion. (NIH,VA)
Role of MMP‐2 activation in oncostatin‐M induced cardiomyocyte dedifferentiation
Authors: Fan Frank (Xiaohu) , Ali Mohammad A.M. , Hughes Bryan G. , Schulz Richard
Published: June 2021

Despite the dogma that adult mammalian cardiomyocyte is terminally differentiated, these cells have a discrete regenerative capacity in both acutely and chronically injured human hearts. Dedifferentiation of cardiomyocytes is an important source of cardiac progenitor cells facilitating cardiac repair. Oncostatin‐M (OSM) can induce cardiomyocyte dedifferentiation characterized by sarcomere degeneration. However, the detailed mechanism regarding the downstream execution of sarcomere degeneration remains unclear. Matrix metalloproteinase‐2 (MMP‐2) is an important intracellular protease known to cleave multiple sarcomeric proteins including α‐actinin, troponin‐I and titin. We studied the dynamics of sarcomere degeneration upon stimulation of neonatal rat ventricular cardomyocytes (NRVM) with OSM. As early as 48 hr after OSM (50ng/ml) treatment, changes in sarcomeric structure were observed. Z‐bands stained for α‐actinin were degenerated towards Z‐bodies and M lines stained for titin also showed a similar pattern. The beating rate of NRVM significantly decreased, consistent with the observed sarcomere degeneration. Western blots and gelatin zymography analysis show increased MMP‐2 activity and loss of α‐actinin and troponin I following OSM treatment. These results suggest the possible involvement of MMP‐2 in cardiomyocyte dedifferentiation stimulated by OSM.

Funding: Canadian Institutes of Health Research