bluuebunny/crossref_metadata_2025 huggingface dataset:
ADAM17 and Impaired Endothelial Insulin Signaling in Type 2 Diabetes
Authors: Restaino Robert M. , Castorena‐Gonzalez Jorge A. , Marshall Kurt D. , Padilla Jaume , Martinez‐Lemus Luis A.
Published: November 2023

Endothelial dysfunction and impaired insulin signaling are hallmark vascular abnormalities associated with cardiovascular pathogenesis in type 2 diabetes (T2D). Such abnormalities result from impaired insulin‐induced activation of endothelial nitric oxide synthase (eNOS). Hyperglycemia in T2D has been associated with an aggregation of misfolded proteins and resultant endoplasmic reticulum (ER) stress with activation of the unfolded protein response (UPR) in various cell types. Herein, following immunohistochemical examination of mesenteric arteries from T2D patients undergoing bariatric surgery, we show a reduction (P<0.05) in the presence of the insulin receptor alpha subunit (IRα) in all three layers of the vascular wall, notably within the endothelium vs. that in vessels from Non‐T2D individuals. The reduced presence of IRα was associated with an upregulation of ADAM17, an enzyme that is involved in cleavage of outer membrane proteins. We hypothesize that hyperglycemia in T2D induces an upregulation in ADAM17 expression and activity leading to cleavage of IRα from the cell membrane in an ER stress dependent mechanism. To test this hypothesis, serum‐starved human umbilical vein endothelial cells were exposed over night to 5mM glucose (control), 30mM glucose (hyperglycemia) or 0.5μM phorbol 12‐myristate 13‐acetate (PMA, a PKC activator) in 5mM glucose as a positive control of ADAM17 induction. These treatments were administered alone or in combination with the ER stress alleviator tauroursodeoxycholic acid (TUDCA). Cells were harvested for determination of ADAM17 expression and activity. Following treatment with high glucose and PMA, ADAM17 expression was significantly increased (n=7, P<0.05 compared to control) in endothelial cells. Concurrent treatment with TUDCA reduced (n=7, P<0.05) expression of ADAM17 in the hyperglycemic condition. ADAM17 activity was elevated under both hyperglycemic and PMA conditions (fold change from control hyperglycemia=1.97±0.15 A.U., PMA=1.84±0.23 A.U.; n=8, P<0.05) and not affected by TUDCA (p>0.05). Taken together, these results suggest a potential role of ADAM17 in mediating endothelial cell insulin resistance through cleavage of IRα from the cell membrane. This mechanism could be secondary to hyperglycemia‐induced ER stress in T2D.

Support or Funding Information

National Institutes of Health HL‐125503 and DK‐105368 to J.P., HL‐073101 and HL‐088105 to L.A.M‐L.
Heterogeneity of TRPV4 Expression and Function in Endothelial Cells of Different Vascular Beds
Authors: Maishan Mazharul , Lamb David , Lee Warren L , Kuebler Wolfgang M
Published: November 2023

Introduction

The ubiquitously expressed calcium channel transient receptor potential vanilloid subtype 4 (TRPV4) has been implicated in various endothelial functions. Specifically, TRPV4 activation triggers endothelial barrier failure. In the lung, TRPV4‐mediated pulmonary edema formation has been reported in response to various triggers including acid aspiration and positive pressure ventilation. Thus, TRPV4 is a promising target for preventing or treating lung injury, but its ubiquitous expression requires investigating potential off‐target effects during therapeutic modulation.

Methods

The present study is working toward this aim by comparing TRPV4 expression and function in human endothelial cells from five different vascular beds: pulmonary (HPMEC), cerebral (HCMEC) and adipose (HAMEC) microvascular as well as pulmonary artery (HPAEC) and coronary artery (HCAEC). Response to the TRPV4 agonist GSK1016790A was assessed by ratiometric Fura‐2 imaging of intracellular calcium concentration [Ca2+]i, measuring transendothelial electrical resistance (TEER), and fluorescence imaging of cytoskeletal actin and VE‐cadherin. TRPV4 protein expression was densitometrically quantified by Western blot, normalized to GAPDH for comparison between the five cell types.

Results

Agonist treatment increased [Ca2+]i and decreased TEER in all endothelial cell types studied, while vehicle (dimethylsulfoxide) had no effect. Interestingly, there was strong inverse correlation between the [Ca2+]i response and decrease in TEER amongst the three microvascular cell types, HPMEC, HAMEC and HCMEC, with the [Ca2+]i and reduction of TEER increasing in the order HPMEC < HAMEC < HCMEC. This effect was corroborated by fluorescence imaging that showed TRPV4 agonism caused intercellular adherens junctions to become disrupted and gaps to form within the endothelial monolayer. In some cases, endothelial cells significantly contracted and became rounded, losing surface VE‐cadherin and forming actin stress fibers. The degree of this effect varied between microvascular cells, again in the increasing order HPMEC < HAMEC < HCMEC. Furthermore, these observations correlated with quantification of Western blot showing HCMECs had highest expression of TRPV4 protein. Notably, while macrovascular HPAECs and HCAECs showed quantitatively similar responses as microvascular endothelial cells, they did not fit the linear regression between [Ca2+]i and TEER response.

Conclusion

These results demonstrate quantitative heterogeneity in endothelial TRPV4 function in different vascular beds, and identify TRPV4 as a major regulator of microvascular endothelial cell permeability, while confirming the established differences in barrier function between micro‐ and macrovascular endothelial cells.

Support or Funding Information

Canadian Institutes of Health Research (CIHR)

Ontario Research Fund (ORF)
N‐cadherin strengthens VE‐cadherin adhesion through Trio/Rac1 signaling
Authors: Kruse Kevin Jonathan , Huang Fei , Sun Ying , Vogel Steve , Malik Asrar , Komarova Yulia
Published: November 2023

The vascular endothelium is comprised of a monolayer of endothelial cells (ECs) lining the blood vessels, which functions as a semi‐permeable barrier between blood and the surrounding tissue. Vascular Endothelial (VE)‐cadherin, which forms homotypic adhesions between ECs at adherens junctions (AJs), is the main adhesive molecule that restricts the passage of protein rich fluids across the endothelial monolayer. Along with VE‐cadherin, ECs express Neural (N)‐cadherin, which is excluded from AJs but forms heterotypic adhesions between ECs and mural cells at the abluminal surface of the endothelium. While the role of VE‐cadherin adhesion in regulating endothelial barrier function has been well established, the role of N‐cadherin in ECs remains mainly unknown. We have demonstrated that inducible deletion of Cdh2 gene (encoding N‐cadherin in endothelial cells of adult mice) results in increased permeability of the endothelial vessel wall to albumin in the lung, brain, and kidney. Consistent with these results, accumulation of VE‐cadherin at AJs in endothelial cells of N‐cadherin EC‐KO mice in vivo was significantly reduced. To investigate N‐cadherin adhesion‐mediated signaling in endothelial monolayers, we covalently attached the extracellular domain of N‐cadherin to an Ni‐NTA surface in an oriented manner. N‐cadherin adhesion‐mediated signaling promoted recruitment of VE‐cadherin to AJs. Depletion of N‐cadherin in endothelial cells abolished this effect, suggesting that N‐cadherin adhesion‐mediated signaling promotes assembly of VE‐cadherin adhesion. Using a combination of N‐cadherin coated biomimetic platforms with mass spectroscopy, we isolated and analyzed N‐cadherin complexes. We found that a Rac1 activator, Trio, is recruited to N‐cadherin complexes to activate Rac1 signaling at AJs. This was consistent with formation of lamellipodia protrusions above AJs and increased Rac1 activity as determined by a Rac1 FRET biosensor. Depletion of Trio decreased recruitment of VE‐cadherin to AJs and resulted in a loss of Rac1 activity downstream of N‐cadherin adhesion. These data cumulatively demonstrate that N‐cadherin promotes assembly of VE‐cadherin adhesion through Trio/Rac1 signaling.

Support or Funding Information

NIH R01 HL103922

AHA 16PRE27260230
Characterization of exosomes isolated from cultured vascular endothelial and smooth muscle cells
Authors: Boyer Michael , Baggett Ariele , Scalia Rosario , Eguchi Satoru , Rizzo Victor
Published: November 2023

Exosomes are small nanovesicles derived from endosomal compartments termed multivesicular bodies. Upon biogenesis, the multivesicular bodies fuse with the plasma membrane, releasing the exosomes, which contain functional nucleic acids and proteins. Despite their well‐documented existence, not much is known about vascular exosomes. The basic architecture of a blood vessel consists of the intima, media, and adventitia. The luminal surface of the intima consists of a confluent monolayer of endothelial cells (ECs), while the medial layer is characterized by presence of vascular smooth muscle cells (VSMCs). We characterized the exosomes released by these cell types in culture in order to better understand the packaging of these vesicles and their capacity to participate in potential cell‐to‐cell communication. Rat aortic ECs exosomes were generated in serum‐free media for 48 hours while rat aortic VSMC exosomes were generated in serum‐free media for 72 hours. Media harvested from both was ultracentrifuged at 10,000×g to remove microparticles followed by centrifugation of the supernatant at 100,000×g to pellet exosomes. Exosome pellet was washed once using PBS and spun at 100,000×g. Transmission electron microscopic analysis of VSMC exosomes confirmed particle morphology with diameters ranging from 60–150 nm. Quantitative evaluations of particle size and concentration were further performed using NTA NanoSight. Average sizes of EC exosomes and VSMC exosomes were 161.9±49.9nm and 176.7±66.4nm, respectively. The concentrations of EC and VSMC exosomes were 2.24×1010 particles/mL/day and 7.63×1010 particles/mL/day, respectively. Western blotting analysis was performed to characterize common and specific markers for vascular exosomes. We found common exosome makers in both ECs and VSMCs, such as flotillin‐1 and CD81. ECs specifically expressed VE‐cadherin and TSG‐101 whereas VSMC expressed syntenin‐1. From our data, we conclude that exosomes are constitutively released from these cell types and play a potential role in vascular cell‐to‐cell communication. The methods herein provide useful information regarding the characterization of vascular exosomes in cardiovascular physiology.
Physical training improves cardiac structure and function, antioxidant capacity, and exercise tolerance in spontaneously hypertensive rats
Authors: Okoshi Marina Politi , Pagan Luana , Damatto Ricardo , Cezar Marcelo , Campos Dijon , Lima Aline , Damatto Felipe , Gomes Mariana , Caldonazo Tulio , Okoshi Katashi
Published: November 2023

Introduction

Chronic hemodynamic overload such as hypertension induces genetic, molecular, cellular, and interstitial alterations which clinically manifest as changes in heart size, shape, and function, a process known as cardiac remodeling. Pressure overload caused by hypertension may produce imbalance between reactive oxygen species (ROS) production and antioxidant capacity. Exercise plays an important role in mitigating cardiovascular risk factors such as hypertension. The aim of this study was to evaluate the influence of physical training on cardiac structures and function, physical capacity, and myocardial oxidative stress in spontaneously hypertensive rats (SHR).

Methods

Thirteen month old SHR were divided into two groups: sedentary (SED, n=18) and exercised (EX, n=22). Physical training was performed 5 times per week for 16 weeks on a treadmill. Physical performance was assessed by exercise test on a treadmill with a gradual speed increase. Systolic arterial pressure (SAP) was measured by tail cuff method. Echocardiogram (Echo) was performed to evaluate in vivo cardiac structures and left ventricular (LV) function. In vitro myocardial function was analyzed in LV papillary muscle preparations. Cardiomyocyte size was measured in LV histological sections. Myocardial antioxidant enzyme activity was quantified by spectrophotometry. NADPH oxidase activity was analyzed by the lucigenin reduction method. Statistics: Student's t test (p<0.05).

Results

Physical capacity was higher in EX. SAP did not differ between groups at the end of the experiment (SED 194 ± 22 vs. EX 188 ± 12 mmHg). Echo showed reduced diastolic posterior wall thickness (SED 1.63 ± 0.10 vs. EX 1.53 ± 0.08 mm), left atrium diameter (SED 6.57 ± 0.51 vs. EX 6.18 ± 0.49 mm), left atrium diameter‐to‐aorta diameter ratio (SED 1.49 ± 0.11 vs. EX 1.42 ± 0.13), and LV relative wall thickness (SED 0.43 ± 0.05 vs. EX 0.40 ± 0.04) in EX group. The in vitro myocardial functional study showed better performance in EX (positive derivative of tension developed: SED 52.2 ± 12.4 vs. EX 63.4 ± 9.49 g/mm2/s). Cardiomyocyte size and NADPH oxidase activity did not differ between groups. Antioxidant enzymes superoxide dismutase and catalase activity was higher in EX.

Conclusion

Physical training improves exercise capacity and induces beneficial effects on cardiac structures and function and myocardial antioxidant capacity in spontaneously hypertensive rats.

Support or Funding Information

Support: FAPESP, CNPq, and CAPES
Effects of Eccentric and Concentric Cycling Exercise Regimens on Hemodynamic and Hemorheologic Properties in Sedentary Males
Authors: Huang Chi‐Yao , Wang Jong‐Shyan
Published: November 2023

Erythrocyte rheological properties significantly contribute to the dynamic regulation of vascular resistance to flow shear force, whereas impaired rheological functions of erythrocytes lead to circulatory disorders and exercise intolerance. This study investigated whether eccentric (ECE) and concentric (CCE) cycling exercise regimens influence hemorheological/hemodynamic responses to hypoxic stress in sedentary males. Twenty‐two healthy sedentary men were randomized to either ECE (n=11) or CCE (n=11) group. These subjects progressively performed ECE or CCE at 45% to 70% VO2max on a bicycle ergometer for 40 min/day, 5 days/week for 6 weeks. Erythrocyte rheological and central/peripheral hemodynamic characteristics at rest and after hypoxia exercise test (HE, 100W under 12% O2 for 40 min) were determined by laser diffraction ektacytometer and bioreactance‐based device/near infrared spectrometer, respectively. The result demonstrated that HE reduced erythrocyte deformability and increased erythrocyte aggregability under shear flow whereas CCE rather than ECE attenuated the extents of erythrocyte rheological impairment caused by HE. Although cardiac hemodynamic responses to exercise in the ECE group were smaller than those in the CCE group, the percentages of blood distributed to frontal cerebral lobe and vastus lateralis muscle in ECE group were larger than those in CCE group. Hence, we conclude that CCE effectively increases the resistance to hemorheological impairment evoked by HE, whereas ECE prominently enhances cerebral/muscular hemodynamic adaptions to exercise in sedentary males.
Heart Rate Recovery Improvement Is Greater After Evening Than Morning Aerobic Training In Treated Hypertensive Men
Authors: de Brito Leandro Campos , Peçanha Tiago , Fecchio Rafael , Rezende Rafael , Sousa Patricia , Silva Giovânio , Abreu Andrea , de Mion Decio Campos , Halliwill John , Forjaz Claudia
Published: November 2023

Introduction

In hypertensive individuals, aerobic training improves heart rate recovery (HRR), which reflects an improvement on cardiovascular autonomic regulation. However, autonomic function is influenced by time of day, being possible to suppose that training at different times of day might promote different autonomic adaptations, which need to be investigated.

Objective

To compare the effect of aerobic training performed in the morning and in the evening on HRR indexes of hypertensive men.

Methods

Forty treated hypertensive men were allocated into four groups: morning control (MC, n=9); morning training (MT, n=12); evening control (EC, n=9); evening training (ET, n=10). Training groups performed cycle ergometer exercise 3 times/week for 45 min at an intensity that progressed from the heart rate (HR) at anaerobic threshold to the HR 10% below the respiratory compensation point. Control groups performed stretching exercise 3 times/week for 30 min. At the beginning of the study and after 10 weeks, all subjects underwent, two maximal exercise tests, in a random order: one conducted in the morning (7 – 9 a.m.) and another in the evening (8 – 10 p.m.). T30 (short‐term time‐constant of HRR – parasympathetic reactivation marker) and HRR300s (HR reduction at 300 s of recovery – sympathetic withdrawal marker) were measured. A 2‐way ANOVA for repeated measures was employed at each time of day assessment, considering the main factors: group (MC, MT, EC, ET) and condition (before vs after the intervention), p≤ 0.05.

Results

For evening assessment, T30 did not change for any group, HR300s did not change in the control groups (MC and EC), but improved significantly in the training groups and this improvement was greater in the ET than MT (MT −45±11 vs. −49±10 bpm and ET −45±13 vs. −53±10 bpm, p<0.04). For morning assessment, there were no changes for either T30 or HRR300s, in any group.

Conclusion

Aerobic training improves sympathetic withdrawal after a maximal exercise test performed in the evening, and this adaptation is more evident when training is performed in the evening.

Support or Funding Information

Financial support: FAPESP: 2014/21667‐6. FAPESP: 2016/19090‐8.
Regulation of Autophagy during Chronic Contractile Activity‐Induced Muscle Adaptations
Authors: Kim Yuho , Triolo Matthew , Hood David A
Published: November 2023

Autophagy is integral in the remodeling of skeletal muscle in response to various stimuli such as energy status, exercise, and/or other cellular stress. However, it currently remains obscure how autophagy is regulated in skeletal muscle over the course of training adaptations. In this study, we examined autophagic regulation in skeletal muscle of rats exposed to chronic contractile activity (CCA; 6 hours/day, 9V, 10 Hz continuous, 0.1 ms pulse duration) for 1, 3, and 7 days (N=8/each group). CCA resulted in muscle mitochondrial adaptation by day 7, as shown by the increase in PGC‐1α, a master regulator of mitochondrial biogenesis. This was supported by significant increases in other mitochondrial markers such as COX‐I and COX‐IV protein levels, as well as COX activity. Notably, the ratio of LC3 II/LC3 I, an indicator of autophagy, decreased by day 7 largely due to a significant increase in LC3 I. Furthermore, autophagic induction marker p62 appeared to be elevated on day 3 and returned to basal levels by day 7. We found that the lysosomal system is concomitantly upregulated in response to training whereby TFEB, a primary regulator of lysosomal biogenesis, increased 2‐fold by day 7 along with other lysosomal markers including LAMP1, LAMP2A, and MCOLN1. Our findings suggest that, in response to chronic exercise, autophagy is upregulated prior to mitochondrial adaptations, and the lysosomal system may play an important role in mediating autophagy and mitochondrial turnover in skeletal muscle during adaptations to a higher mitochondrial content.

Support or Funding Information

This work is supprted by Natural Sciences and Engineering Research Council of Canada (NSERC).
One‐Step Real Time RT‐PCR for the Detection of Exercise‐Inducing Circulating MicroRNAs in Sedentary Males
Authors: Chen Kuan‐Ming Jacky , Huang Ching‐Hui , Lin Ke‐Ting , Wang Jong‐Shyan
Published: November 2023

Circulating microRNAs (c‐miRNAs) derived from endothelium and skeletal muscle can response to acute exercise and exercise training. However, the commonly used protocols are usually costly and time consuming. Hence, this study developed a four‐primers‐based miRNA quantification method, and simultaneously performed both reverse transcription and PCR by a one‐step operation on a real‐time system. Moreover, we designed the specific primers for two “exercise‐inducing” c‐miRNAs: Hsa‐miR‐133a‐3p is distinctly expressed in cardiac and skeletal muscles and hsa‐miR‐126‐3p is dominant expressed in endothelium. Additionally, we also developed primers targeting to the synthetic internal control miRNA, cel‐miR‐39‐3p, which is added during RNA extraction. The results showed that excellent linearity (R2=0.9998) between the Ct values and the logarithms (log) of miRNA amount was observed in the range from 6.1 attomole to 6.3 femtomole of cel‐miR‐39‐3p. Furthermore, maximal graded exercise significantly increased has‐mir‐126‐3p (52±28%, p<0.05) and hsa‐miR‐133a‐3p (113±35%, p<0.05) in healthy sedentary males (n=12). Therefore, we conclude that one step RT‐qPCR is reliable and efficient, and has the superiority in the high throughput routing assay of c‐miRNAs. According to the methodology, acute strenuous exercise increases the releases of muscle/endothelium‐related miRNAs into the peripheral blood compartment in sedentary males.
Physiological cardiac hypertrophy of exercise training is absent in mice deficient in adiponectin
Authors: Muller‐Delp Judy Marie , Dieseldorf‐Jones Karissa Marie , Pinto Jose Marie , Burodonovich Kyle , Hotta Kazuki , Delp Michael , Behnke Bradley
Published: November 2023

Adiponectin is known to exert protective effects in the post‐ischemic myocardium; however, its role in physiological cardiac hypertrophy induced by exercise training remains unknown. We tested the hypothesis that adiponectin is necessary in exercise training‐induced physiological cardiac hypertrophy. Adult C57BL/6 wild‐type (WT) or homozygous adiponectin knockout (AdipoKO) mice were obtained at 10 wks of age and underwent treadmill exercise training (12 m/min, 5° incline, 1 hr/day, 5 days/wk for 8 wks) or remained sedentary in cages. At the beginning and end of the exercise training or cage confinement period, echocardiographic assessment of cardiac function was performed with the Vevo 2100 high‐resolution imaging system. M‐mode imaging was used to evaluate systolic and diastolic dimensions, posterior and anterior wall thickness, fractional shortening and ejection fraction. Pulsed‐wave doppler was used to measure early (E wave) and late (A wave) mitral valve inflow, and to calculate isovolumic relaxation time. In WT mice, exercise training increased left ventricular (LV) mass, and anterior and posterior wall thickness, without a change in chamber diameter. End‐systolic volume decreased with exercise training, contributing to increased ejection fraction. Fractional shortening also increased with exercise training in WT mice. In contrast, in WT and KO sedentary mice, LV mass and anterior and posterior wall thickness did not change over the 8‐wk period. In sedentary WT mice, chamber diameter did not change, but in sedentary Adipo KO mice, chamber diameter increased over 8 wks. In Adipo KO mice, 8 weeks of exercise training did not produce the adaptations that occurred in WT mice. As in sedentary KO mice, LV mass and anterior and posterior wall thickness did not change over the 8‐wk period of training. Ejection fraction and fractional shortening decreased and end‐systolic volume increased during the 8‐wk training period in Adipo Ko mice. Similar to sedentary Adipo KO mice, chamber diameter increased in exercise trained Adipo KO mice. These data indicate that the outward hypertrophy and increased systolic function that occurs with exercise training in young adult mice is absent in age‐matched adiponectin‐deficient mice. Thus, these results suggest that adiponectin is required for the physiological hypertrophy that is induced by exercise training in the healthy, adult heart.

Support or Funding Information

NIH R21 AG044858
The Effect of an Antioxidant Cocktail on Indices of Cerebral and Peripheral Vascular Function in Healthy College‐Age Men
Authors: Curtis Bryon M , Patik Jordan C , Vranish Jennifer R , Kaur Jasdeep , Young Benjamin E , Fadel Paul J , Brothers R. Matthew
Published: November 2023

The detrimental effect of systemic oxidative stress on vascular function has been well documented, yet there is disagreement in the literature regarding the capacity of oral antioxidants to mitigate these effects. However, the majority of these studies have assessed the role of oxidative stress using a single antioxidant treatment (i.e. Vitamin C only). Recently it was reported that an oral antioxidant cocktail (AOX) consisting of vitamin C (2g), vitamin E (150IU), and coenzyme Q10 (100mg) significantly reduced oxidative stress, muscle sympathetic nerve activity, and blood pressure in relatively young and healthy adults. Whether this AOX also improves indices of vascular function remains unknown. Thus, the purpose of this current investigation was to test the hypothesis that an AOX would augment indices of cerebral and peripheral vascular function. 7 relatively young healthy men (age: 24 ± 5 yr) participated in this protocol. All measures were obtained in the morning following an overnight fast during 2 separate visits to the laboratory separated by ~ 1 week, with AOX or a placebo (three sugar pills) being administered in random order. Cerebral vascular function was assessed as the increase in cerebral vascular conductance (CVCI: middle cerebral artery blood velocity (MCAVmean)/mean arterial pressure (MAP)) before and during rebreathing‐induced hypercapnia. Peripheral vascular function was assessed as flow‐mediated dilation (FMD) of the brachial artery following a 5 min period of cuff occlusion. Arterial stiffness was also assessed via augmentation index (AIX@75) and pulse‐wave velocity (PWV), using brachial pulse wave analysis and applanation tonometry, respectively. The increase in CVCI during the highest common elevation in end‐tidal carbon dioxide achieved between the two days was similar (placebo: 130 ± 10% of baseline, AOX: 128 ± 3% of baseline; P=0.77). Likewise, FMD (placebo: 5.3 ± 2.2% of baseline, AOX: 5.5 ± 1.6% of baseline; P=0.55), AIX@75 (placebo: −8.8 ± 14.2%, AOX: −5.7 ± 8.3%; P=0.33), and PWV (placebo: 6.3 ± 0.9 m/s, AOX: 6.1 ± 0.9 m/s; P=0.55) were not different between AOX and placebo study visits. Contrary to our hypothesis, these preliminary findings suggest that AOX does not affect indices of cerebral or peripheral vascular function in relatively young and healthy men.
Effects of Hybrid Exercise Program on Subclinical Vascular Markers in Young Patients with Permanent Lower‐Limb Disability
Authors: Suksom Daroonwan , Srihirun Kanang , Siripatt Apanchanit , Siripanya Saowalak , Tanaka Hirofumi
Published: November 2023

Patients with permanent lower limb disability rely on wheel chair for transportation and daily activities. These patients suffer from a lack of physical activity and experience markedly elevated risks of cardiometabolic diseases. In the present study, we investigated the effects of hybrid upper body exercise program on physical fitness and vascular functions in young patients with permanent lower limb disability. Twenty nine males and females with permanent lower limb disability aged 26.0±1.4 years were randomly assigned into the sedentary time control (CON; n=15) and the exercise training (ET; n=14) groups. The supervised exercise training program consisted of a variety of upper limb exercises, including stretching exercises, moderate intensity aerobic exercise incorporating elements of Muay Thai and resistance exercise with rubber strings for 40 min/day, 3 days/wk, for 12 weeks. Before and after the exercise interventions, physical fitness and blood biochemistry were assessed in all participants. A variety of vascular functions including arterial wall thickness, carotid intima‐media thickness (IMT), vascular reactivity, flow‐mediated dilatation (FMD), and brachial‐ankle pulse wave velocity (baPWV), an index of arterial stiffness, were measured noninvasively. At baseline, two groups were not different in anthropometric and vascular functional measures. After 12 wks, there were no significant changes in body fat, heart rate at rest, and systolic blood pressure in both groups. Diastolic blood pressure decreased significantly (p<0.05) only in the ET group. Forearm muscle strength increased significantly (p<0.05) in both CON and ET groups. The ET group experienced greater increases in flexibility and maximal oxygen consumption than the CON group (all p<0.05). IMT and baPWV did not change significantly in both groups. FMD increased significantly (p<0.05) only in the ET group. These results indicate that aerobic exercise training combined with resistance exercise training program had beneficial effects in improving flexibility, cardiovascular fitness, and macrovascular functions in patients with permanent lower limb disability.

Support or Funding Information

Supported by Physical Activities Research Center, Thai Health Promotion Foundation.
Sympathetic Nervous System Activation Reduces Contraction‐induced Rapid Vasodilation in the Leg of Humans Independent of Age
Authors: Hughes William E , Kruse Nicholas T , Casey Darren P
Published: November 2023

Aging is associated with attenuated vasodilation and hyperemia following a single skeletal muscle contraction in both the arm and leg. We previously demonstrated that enhanced sympathetic vasoconstrictor tone contributes to the blunted skeletal muscle contraction‐induced rapid onset vasodilation (ROV) in the forearm of older adults. However, evidence suggests that limb‐specific differences in the regulation of vascular tone exist with aging. Therefore, we sought to examine whether elevated sympathetic tone in the leg contributes to the age‐related reductions in contraction‐induced ROV. Healthy, young (n=13; 24±1yr; 7M/6F) and older (n=10; 67±1yr; 6M/4F) adults performed single muscle contractions in the right leg [20% and 40% work rate maximum (WRmax)] under control (no sympathetic stimulus) and enhanced sympathetic nervous system activity (via a cold pressor test; CPT) conditions. CPT testing consisted of placing the left foot in an ice‐water bath (4° C) for 4 minutes. Femoral artery diameter and mean blood velocity were measured using Doppler ultrasound. Leg vascular conductance (VC; ml· min−1· 100mmHg−1) was calculated using blood flow (mL· min−1) and mean arterial pressure (mmHg). Under control conditions, peak (ΔVC from baseline) and total (area under the curve over 30 cardiac cycles post contraction) vasodilator responses were attenuated in older adults across exercise intensities (P<0.05). Increased sympathetic vasoconstrictor tone via CPT reduced peak and total VC responses in both young and older adults across exercise intensities (P<0.05). The magnitude (%) of reduction did not differ between young vs. older adults for peak (20% WRmax: −25±5% vs. −22±4%, P=0.57 and 40% WRmax: −21±6% vs. −29±6%, P=0.37) or total VC (20% WRmax: −28±5% vs. −37±7%, P=0.29 and 40% WRmax: −22±8% vs. −35±7%, P=0.20). Due to differences in WRmax between age groups, comparisons in the ROV response were also made in a subset of subjects (9 young/8 older) matched for an approximate absolute workload (~10W). Workload matched responses revealed that age‐associated reductions in peak ΔVC and total VC under control conditions still persisted (P<0.05). Moreover, there were no differences in the magnitude of reduction in peak (−20±7% vs. −24±5%, P=0.34) or total VC (−22±8% vs. −29±4%, P=0.23) between young vs. older adults during the CPT trials. Our data demonstrate that 1) independent of age, sympathetic stimulation via CPT reduces parameters of ROV in the leg; and 2) the substantial reductions in leg ROV with aging does not appear to be explained by elevated sympathetic vasoconstrictor tone.

Support or Funding Information

Funded by NIH HL‐105467 (DPC)
Combined Effect of Heating and Electrical Stimulation on Endothelial Vasodilator Function
Authors: Iwamoto Erika , Oiwa Shotaro , Takami Jiro , Nagaoka Ryohei , Ito Shota , Neki Toru , Katayose Masaki
Published: November 2023

Endothelial dysfunction contributes to the progression of atherosclerotic disease. Recent studies suggest electrical stimulation (ES) has a beneficial effect on endothelial function. Additionally, local heating also enhances endothelial function via an increase in skin blood flow and shear stress. Interestingly, ES alone can lead to a small increase in skin blood flow, whereas the combination of ES and local heating could generate a synergistic effect on skin blood flow. Therefore, the aim of this study was to test the hypothesis that combined local heating and ES provide the additive improvement on endothelial function than heating and ES alone. On three separate visits, brachial artery flow‐mediated dilation (FMD), an index of endothelium‐dependent vasodilator function, was assessed before and immediately after 30‐min of exposure to electrical stimulation (ES), heating (Heat), or combined electrical stimulation and heating (ES+Heat) in seven young male subjects (Age; 22.3±1.8 years, BMI; 22.1±0.6 kg/m2, Mean±SE). ES was delivered by an electrical stimulator and surface electrodes (5×5cm) placed bilaterally over the right brachioradialis and extensor carpi ulnaris muscles. Heat was performed using a heating pad (42–43□) wrapped around the right forearm. Brachial blood flow and shear rate and forearm skin blood flow were measured throughout each intervention. Skin blood flow at 30 min was increased (% change from baseline) with Heat (300±64%, p=0.001) and ES+Heat (345±69%, p<0.001), but not ES alone (98±20%, p=0.182). Brachial shear rate at 30 min of ES+Heat was higher than that in Heat (ES+Heat vs. Heat. 168±13 vs. 101±14 sec−1, p=0.026). However, brachial shear rate in ES+Heat vs. ES alone did not differ (168±13 vs. 122±16 sec−1, p=0.162). Importantly, ES+Heat induced a significant increase in FMD after the intervention (Pre vs. Post. 4.5±0.4 vs. 6.7±0.7%, p=0.042), whereas FMD did not change with Heat alone (5.2±0.3% vs. 6.1±0.6%, p=0.342) and ES alone (4.8±0.4 vs. 5.0±0.8%, p=0.804). These results demonstrated that combined heating and electrical stimulation could be an effective method to increase endothelial vasodilator function.

Support or Funding Information

This study was supported in part by Grant‐in‐Aid for Scientific Research from the Japanese Ministry of Education, Science, Sports, and Culture (Grant No. 25750208, 16K16432)
Effects of Aerobic Capacity on Arterial Stiffness in Individuals with Multiple Sclerosis
Authors: Grigoriadis Georgios , Rosenberg Alexander J. , Wee Sang Ouk , Schroeder Elizabeth C. , Hilgenkamp Thessa I.M. , Griffith Garett , Baynard Tracy
Published: November 2023

INTRODUCTION

Individuals with Multiple Sclerosis (MS) exhibit a greater risk of cardiovascular disease than individuals without MS, and increased arterial stiffness is one possible risk factor. Higher aerobic capacity has been associated with lower arterial stiffness in healthy individuals and helps explain lower risk profiles. Individuals with MS in general have low aerobic capacities and the effect of MS may abolish expected relationships between fitness and arterial stiffness.

PURPOSE

To determine the relationship between peak oxygen consumption (VO2peak) and carotid arterial stiffness in individuals with MS.

METHODS

Thirteen individuals with MS (43 ± 9 yrs; 25.0 ± 3.7 kg/m2) underwent an individualized incremental treadmill test to volitional exhaustion with measures of oxygen uptake. Carotid arterial stiffness was measured by ultrasonography prior to the treadmill test, and echo‐tracking software was used to calculate the β‐stiffness index, pressure‐strain elasticity modulus (Ep) and arterial compliance (AC). Bivariate correlations were implemented to examine the linear relationship between VO2peak and carotid arterial stiffness. Partial correlations were performed to control for body weight.

RESULTS

Negative correlations were observed between absolute VO2peak and β‐stiffness index, (p<0.05) and Ep (p<0.05), whereas a positive correlation was found with AC (p<0.05). However, the significance between VO2peak and carotid stiffness variables was eliminated when controlling for body weight.

CONCLUSION

The findings suggest that aerobic capacity is negatively associated with carotid arterial stiffness and positively associated with arterial compliance, while body weight influences these relationships in an expected manner. Thus, aerobic training and/or weight loss might be an effective treatment to decrease arterial stiffness and consequently risk of cardiovascular disease in a population with MS.

Arterial Stiffness Variables
Absolute VO2peak Bivariate Correlation
Absolute VO2peak Partial Correlation

β‐stiffness index
−0.604*
−0.421

Ep (kPa)
−0.682*
−0.529

AC (mm22/kPa)
0.672*
0.508

Significant correlation: p<0.05
Genetic Risk Factors of Chronic Mountain Sickness
Authors: Richalet Jean‐Paul , Gazal Steven , Espinoza Jose R , Austerlitz Frédéric , Macarlupu Jose Luis , Leon‐Velarde Fabiola , Marchant Dominique , Gouya Laurent
Published: November 2023

Chronic mountain sickness (CMS) is a pathological condition resulting from the loss of adaptation to high altitude. The syndrome is characterized by an excessive number of red blood cells (Excessive Erythropoiesis) associated with a high concentration of hemoglobin, hypoxemia and sometimes pulmonary hypertension. In the Peruvian Andes, the estimated prevalence of this condition is higher than 10% in the adult population living above 2500 m. The pathophysiology is not yet clearly established. Alteration of the control of ventilation, especially during sleep could induce a severe hypoxemia that would trigger excessive secretion of erythropoietin (EPO), leading to increased red cell production. We collected clinical and physiological data and blood samples in a cohort of 143 CMS patients and 101 control subjects living at high altitude in Cerro de Pasco (4300m). Leukocytes DNA was extracted by salting out procedure, DNA was quantified and qualified with NanoDrop™ 2000. We performed a genome wide association study using an Illumina HumanOmni5 array (4,301,332 SNPs). CMS was associated with low arterial O2 saturation and high body mass index. We evidenced several genes that could be related to a susceptibility to develop CMS or pulmonary hypertension (ATM, NPAT, PPARGC1A, ATP9A, WWOX). These pathways revealed as submitted to recent positive selection. Moreover, the admixture level of European low lander ancestry in the genome of this population seemed to influence the occurrence of CMS and the polymorphism of selected genes. A replication study is planned to confirm our preliminary results.

Support or Funding Information

Laboratory of Excellence GrEx
Chronic intermittent hypoxia decreases the levels of corticotropin‐releasing hormone receptor 2 in the nucleus of the solitary tract in rats
Authors: Wang Lei , Mifflin Steve
Published: November 2023

Corticotropin‐releasing hormone (CRH) has been suggested to play a role in the nucleus of the solitary tract (NTS) to regulate sympathetic activity and cardiovascular function but the distribution of CRH receptors in the NTS is not fully understood. In this study, we used RNAscope in situ hybridization and CD IGS rats to examine the mRNA levels of CRH receptor type 1 (CRHR1) and CRH receptor type 2 (CRHR2) in regions of the NTS (13.68 mm – 14.76 mm caudal to bregma) implicated in the regulation of sympathetic and cardiovascular function. The results showed that both CRHR1 and CRHR2 were expressed in the NTS. In general, there was higher mRNA levels of CRHR2 compared to CRHR1 in the NTS with CRHR2 being 319% ± 69% greater than CRHR1. The higher levels of CRHR2 compared to CRHR1 was mainly observed in the middle portion of the NTS we examined (13.8 mm – 14.28 mm caudal to bregma). We investigated whether CRHR1 and CRHR2 levels were influenced by chronic intermittent hypoxia (CIH), a model of sleep apnea associated with sympathetic excitation and hypertension in rats. We found that CIH did not affect the mRNA levels of CRHR1 but significantly decreased the mRNA levels of CRHR2 in the NTS by 34% ± 14%. These results demonstrate that both CRHR1 and CRHR2 mRNAs are expressed in the NTS and suggest that dys‐regulation of CRHR2 may contribute to CIH‐induced hypertension.

Support or Funding Information

NIH HL088052
Vessel Reactivity and Blood Flow in Rats Exposed to Neonatal Supplemental Oxygen
Authors: Vellookunnel Shilpa , Chandrasekar Shreya , Sturgeon Madison , Murphy Austin , Hoover Michael , Bates Melissa
Published: November 2023

Premature babies make up 12.8% of live births per year. Because their lungs are poorly developed, supplemental oxygen is a necessary treatment. Recent studies in our laboratory in a rat model of prematurity show that aortic pulse wave velocities were higher in rats exposed to neonatal supplemental oxygen, indicating significant aortic stiffening. This study aims to determine if supplemental oxygen also affects the downstream vasculature reactivity. We hypothesized that exposure to supplemental oxygen during the neonatal period will decrease vessel reactivity and we will observe smaller changes in blood flow with hypoxic and hypercapnic (vasodilator) challenges. Twelve month old rats exposed to 80% and 21% oxygen for eight days during the neonatal period were ventilated with hypoxia (12% O2), hypercapnia (5% CO2), and room air in the lab. After 10 minutes of exposure, 10 μm neutron‐activated BioPAL microspheres were injected into the left ventricle and allowed to circulate. The brain, liver, kidneys, spleen and heart were removed, hydrolyzed, and vacuum filtered. Microspheres were used to quantify changes in visceral blood flow. 80% O2 exposed rats and 21% O2 rats showed no significant difference in change in blood flow to the kidney, but further brain and visceral vascular beds are still to be measured. If a significant difference is found in the other vasculature, this would suggest supplemental oxygen exposure would decrease vessel reactivity in premature infants.

Support or Funding Information

The University of Iowa Start‐Up Fund
Ventilatory acclimatization to hypoxia in deer mice native to high altitudes
Authors: Ivy Catherine M , Scott Graham R
Published: November 2023

Hypoxia at high altitudes constrains O2 supply to support metabolism, thermoregulation in the cold, and the aerobic scope needed for exercise. Many highland taxa appear to have physiological specializations for overcoming these challenges, but relatively little is known about the importance of hypoxia acclimation responses in high‐altitude natives, such as ventilatory acclimatization to hypoxia (VAH) and erythropoiesis. Highland taxa often possess a high haemoglobin‐O2 binding affinity, which safeguards arterial O2 saturation (SaO2) and tissue O2 delivery in hypoxia, but could foreseeably affect hypoxia acclimation responses. We examined this issue by comparing captive populations of deer mice (Peromyscus maniculatus) from high and low altitudes. Mice from each population were acclimated to normoxia and moderate hypoxia (12 kPa O2, simulating the PO2 at the native altitude of highlanders at 4300m) for 6–8 weeks. Highland mice were also acclimated to more severe hypoxia (9 kPa, the PO2 at ~7000m), which induces the same SaO2 in highlanders that lowlanders experience at 12 kPa. In lowlanders, hypoxia acclimation augmented the hypoxic ventilatory response (HVR), increased SaO2 in hypoxia, blunted the hypoxic depression of body temperature, increased blood [haemoglobin], and induced right ventricle hypertrophy (a sign of maladaptive pulmonary hypertension). Hypoxia acclimation had little effect on the HVR in highlanders, such that the hypoxic control of breathing appeared to be fixed like that in hypoxia‐acclimated lowlanders. Right ventricle hypertrophy did not occur in either moderate or severe hypoxia in highlanders, suggesting that they have blunted hypoxic pulmonary vasoconstriction and hypertension. The increase in blood [haemoglobin] was lower in highlanders than in lowlanders at 12 kPa, but highlanders mounted a robust increase in severe hypoxia (9 kPa), suggesting that differences in SaO2 and not the erythropoietic process contribute to differences in blood [haemoglobin] between populations. Therefore, high‐altitude adaptation appears to have blunted several hypoxia acclimation responses in deer mice.

Support or Funding Information

Supported by NSERC of Canada.
Perinatal Supplemental Oxygen Alters the Ventilatory and Pulmonary Vascular Responses to Hypoxia in Adult Rats
Authors: Hoover Michael , Greiner Tyler J , Rotella Diane , Vellookunnel Shilpa , Chandrasekar Shreya , Bates Melissa
Published: November 2023

Ascent to altitude is associated with increased ventilation and pulmonary vasoconstriction. These physiological responses are related in healthy subjects such that a high ventilatory drive is associated with blunted pulmonary vasoconstriction. Adults born prematurely and given supplemental oxygen at birth have a blunted ventilatory response to hypoxia. We hypothesized that the hypoxic ventilatory and pulmonary vasoconstrictor responses would be unrelated following neonatal exposure to supplemental oxygen. To test our hypothesis, we used a well‐established rat model of 80% O2 (OXY) exposure for 14 days post‐natally, with 21% O2 exposure as a control (CON). Six‐to‐nine months later, we assessed the ventilatory response to graded hypoxia using barometric plethysmography. We also catheterized the right and left ventricles to evaluate the hemodynamic response to 10 minutes of 12% O2 (hypoxia). We found that, to our surprise, OXY rats did not demonstrate a depressed ventilatory response to hypoxia. However, these animals experienced increased right ventricular systolic pressure in response to 12% O2. This was driven primarily by an increase in cardiac output and not increased vascular resistance. There was no relationship between the hypoxic ventilatory drive and right ventricular pressure. In CON animals, the increase in right ventricular pressure with hypoxia was driven primarily by vasoconstriction and, as expected, there was a relationship between the ventilatory and pressure responses. These data suggest that neonatal supplemental oxygen alters the hemodynamic response to hypoxia, possibly through enhanced sympathetic drive. The relationship between ventilation and pulmonary pressure may not translate to individuals born prematurely.

Support or Funding Information

The University of Iowa Start‐Up Fund