Aerobic exercise training increases neuronal nitric oxide release and bioavailability and decreases noradrenaline release in mesenteric artery from spontaneously hypertensive rats

Tai Chi training as a primary care plan for the prevention and management of hypertension: an opinion and positioning article

Hypertension is a prevalent chronic condition worldwide that can impact patients' quality of life. Oral antihypertensive drugs are widely used to manage high blood pressure, primarily by regulating the renin-angiotensin-aldosterone system. Nevertheless, limited efficacy and low compliance represent significant obstacles, arising primarily from dose, duration, and medication type restrictions. Furthermore, the prolonged use of antihypertensive medication may result in dependence and adverse effects, without any substantial improvement in achieving targeted blood pressure leves. As a result, research has focused on using exercise therapy to treat hypertension. Tai Chi, a widely-practiced Chinese health exercise, has evolved into a form of exercise therapy that might help alleviate the risk associated with hypertension. Therefore, this article aims to outline the role of Tai Chi in preventing and managing hypertension.

The effect of aerobic training on motor function and muscle architecture in children with Duchenne muscular dystrophy: A randomized controlled study

OBJECTIVE

To explore the effects of aerobic training adding to home-based exercise program on motor function and muscle architectural properties in children with Duchenne muscular dystrophy.

DESIGN

This is a prospective randomized controlled study.

SETTING

Pediatric neuromuscular clinic in a tertiary care center.

SUBJECTS

Children with Duchenne muscular dystrophy.

INTERVENTIONS

Children were randomly divided into two groups whereby 12-weeks aerobic training was additionally given in treatment group in contrast to the control group which received only home-based exercise program.

MAIN MEASURES

Motor Function Measure and Six Minute Walk Test were used for clinical evaluation, and muscle architectural properties (thickness, pennation angle and fascicle length) were measured by ultrasound imaging. Both groups were assessed at baseline and after 12-weeks of training.

RESULTS

Median age of children was 7.9 years in the treatment group and 8.6 years in the control group (p > 0.05). Significant improvements were obtained for Motor Function Measure and Six Minute Walk Test from baseline to 12-weeks in the treatment group; Motor Function Measure total score changed from 83.2 (6.1) to 86.9 (4.0) vs. 82.3 (10.2) to 80.4 (9.4) points in the control group (p  =  0.006); 6 Minute Walk Test distance changed from 395.3 (46.6) to 413.0 (52.3) vs. 421.7 (64.4) to 393.8 (68.2) meters in the control group (p < 0.001). However, muscle architectural parameters did not change during study period (p > 0.05).

CONCLUSION

Aerobic training may be of additional value in improving motor function and performance with no remarkable effect on muscle architectural properties.

Supplementation with the Symbiotic Formulation Prodefen® Increases Neuronal Nitric Oxide Synthase and Decreases Oxidative Stress in Superior Mesenteric Artery from Spontaneously Hypertensive Rats

In recent years, gut dysbiosis has been related to some peripheral vascular alterations linked to hypertension. In this work, we explore whether gut dysbiosis is related to vascular innervation dysfunction and altered nitric oxide (NO) production in the superior mesenteric artery, one of the main vascular beds involved in peripheral vascular resistance. For this purpose, we used spontaneously hypertensive rats, either treated or not with the commercial synbiotic formulation Prodefen^® (10⁸ colony forming units/day, 4 weeks). Prodefen^® diminished systolic blood pressure and serum endotoxin, as well as the vasoconstriction elicited by electrical field stimulation (EFS), and enhanced acetic and butyric acid in fecal samples, and the vasodilation induced by the exogenous NO donor DEA-NO. Unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in rats supplemented with Prodefen^®. Both neuronal NO release and neuronal NOS activity were enhanced by Prodefen^®, through a hyperactivation of protein kinase (PK)A, PKC and phosphatidylinositol 3 kinase-AKT signaling pathways. The superoxide anion scavenger tempol increased both NO release and DEA-NO vasodilation only in control animals. Prodefen^® caused an increase in both nuclear erythroid related factor 2 and superoxide dismutase activities, consequently reducing both superoxide anion and peroxynitrite releases. In summary, Prodefen^® could be an interesting non-pharmacological approach to ameliorate hypertension.

Effects of chronic cholinergic stimulation associated with aerobic physical training on cardiac morphofunctional and autonomic parameters in spontaneously hypertensive rats

We investigated hemodynamic, cardiac morphofunctional, and cardiovascular autonomic adaptations in spontaneously hypertensive rats (SHRs) after aerobic physical training associated with chronic cholinergic stimulation. Fifty-four SHRs were divided into two groups: trained and untrained. Each group was further subdivided into three smaller groups: vehicle, treated with pyridostigmine bromide at 5 mg/kg/day, and treated with pyridostigmine bromide at 15 mg/kg/day. The following protocols were assessed: echocardiography, autonomic double pharmacological blockade, heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS). Physical training and pyridostigmine bromide reduced BP and HR and increased vagal participation in cardiac autonomic tonic balance. The associated responses were then potentialized. Treatment with pyridostigmine bromide increased HRV oscillation of both low frequency (LF: 0.2-0.75 Hz) and high frequency (HF: 0.75-3 Hz). However, the association with physical training attenuated HF oscillations. Additionally, treatment with pyridostigmine bromide also increased LF oscillations of BPV. Both treatment groups promoted morphofunctional adaptations, and associated increased ejection volume, ejection fraction, cardiac output, and cardiac index. In conclusion, the association of pyridostigmine bromide and physical training promoted greater benefits in hemodynamic parameters and increased vagal influence on cardiac autonomic tonic balance. Nonetheless, treatment with pyridostigmine bromide alone seems to negatively affect BPV and the association of treatment negatively influences HRV.

Effect of treatment with carvacrol and aerobic training on cardiovascular function in spontaneously hypertensive rats

NEW FINDINGS

What is the central question of this study? Can two non-drug therapies, carvacrol and aerobic physical training, together have additive effects on the reduction of cardiovascular risks and control of arterial hypertension? What is the main finding and its importance? The oral use of carvacrol (20 mg/kg/day) can control sustained hypertension in spontaneously hypertensive rats, and when this use is associated with aerobic physical training, there is a more pronounced effect on the reduction of blood pressure values, making these therapies an adjunct option in the drug treatment of hypertension.

ABSTRACT

Systemic arterial hypertension is considered the foremost cardiovascular risk factor, and it is important to examine different therapies that help prevent and treat it, especially when associated with other cardiovascular risk factors. In this context, it is known that both carvacrol and aerobic physical training benefit the cardiovascular system. This study investigated the effects of treatment with carvacrol combined with aerobic exercise on hypertensive rats with cardiovascular risk parameters. We used an experimental design with six groups: normotensive control (Wistar rats); hypertensive control (spontaneously hypertensive rats, SHR); positive control rats treated with amlodipine (Aml-20 mg); rats treated with carvacrol (Carv-20 mg); rats trained with exercise (Exer); and rats treated with carvacrol and exercise (ExerCarv). The treatment lasted for 4 weeks, monitoring heart rate and systolic blood pressure (SBP). At the end of the treatment, vascular reactivity tests were performed in addition to biochemical measurements of urea, creatinine, aspartate aminotransferase, alanine aminotransferase, triglycerides, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, atherogenic indexes, relative heart weight and histopathological analysis of cardiac perivascular tissue. Significant reductions in SBP were observed after the training period, with the ExerCarv group showing a greater magnitude of reduction (∆SBP = 88 ± 10.0 mmHg, 42%). This group also experienced reductions in atherogenic indices and improvement in all analysed lipid parameters, with no differences observed in the Exer group. The findings indicated that the interaction between aerobic exercise and carvacrol offers a greater BP reduction. Exercise is particularly effective for controlling biochemical parameters of cardiovascular risk, regardless of carvacrol use.

Vasomotor action of androgens in the mesenteric artery of hypertensive rats. Role of perivascular innervation

Androgens may exert cardiovascular protective actions by regulating the release and function of different vascular factors. In addition, testosterone (TES) and its 5-reduced metabolites, 5α- and 5β-dihydrotestosterone (5α- and 5β-DHT) induce vasorelaxant and hypotensive effects. Furthermore, hypertension has been reported to alter the release and function of the neurotransmitters nitric oxide (NO), calcitonin gene-related peptide (CGRP) and noradrenaline (NA). Since the mesenteric arteries possess a dense perivascular innervation and significantly regulate total peripheral vascular resistance, the objective of this study was to analyze the effect of TES, 5α- and 5β-DHT on the neurogenic release and vasomotor function of NO, CGRP and NA. For this purpose, the superior mesenteric artery from male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats was used to analyze: (i) the effect of androgens (10 nM, incubated for 30 min) on the neurogenic release of NO, CGRP and NA and (ii) the vasoconstrictor-response to NA and the vasodilator responses to the NO donor, sodium nitroprusside (SNP) and exogenous CGRP. The results showed that TES, 5α- or 5β-DHT did not modify the release of NO, CGRP or NA induced by electrical field stimulation (EFS) in the arteries of SHR; however, in the arteries of WKY rats androgens only caused an increase in EFS-induced NO release. Moreover, TES, and especially 5β-DHT, increased the vasodilator response induced by SNP and CGRP in the arteries of SHR. These findings could be contributing to the hypotensive/antihypertensive efficacy of 5β-DHT previously described in conscious SHR and WKY rats, pointing to 5β- DHT as a potential drug for the treatment of hypertension.

A Blunted Sympathetic Function and an Enhanced Nitrergic Activity Contribute to Reduce Mesenteric Resistance in Hyperthyroidism

We aimed to determine whether an experimental model of hyperthyroidism could alter the function of sympathetic and nitrergic components of mesenteric innervation. For this purpose, male Wistar rats were divided into (1) control rats (CT) and (2) rats infused with L-Thyroxine (HT). Body weight gain and adipose tissue accumulation were lower in HT rats, while systolic blood pressure and citrate synthase activity in the soleus muscle were increased by HT. In segments from the superior mesenteric artery, the application of an electrical field stimulation (EFS) induced a vasoconstrictor response, which was lower in arteries from HT animals. The alpha-adrenoceptor antagonist phentolamine diminished EFS-induced vasoconstriction to a lower extent in HT arteries, while the purinergic receptor antagonist suramin reduced contractile response to EFS only in segments from CT. In line with this, noradrenaline release, tyrosine hydroxylase expression and activation and dopamine β hydroxylase expression were diminished in HT. The unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in segments from HT rats. NO release was enhanced in HT, probably due to an enhancement in neuronal NOS activity, in which a hyperactivation of both PKC and PI3K-AKT signaling pathways might play a relevant role. In conclusion, perivascular mesenteric innervation might contribute to reduce the vascular resistance observed in hyperthyroidism.

Enhanced sympathetic neurotransduction in the superior mesenteric artery in a rat model of heart failure: role of noradrenaline and ATP

Heart failure (HF) is associated with neurohumoral activation, which in turn leads to an increased peripheral resistance. In mesenteric vasculature, perivascular innervation plays relevant role maintaining vascular tonus and resistance. Therefore, we aimed to determine the possible alterations in superior mesenteric artery (SMA) perivascular innervation function in HF rats. HF was induced by coronary artery occlusion in male Wistar rats, and sham-operated (SO) rats were used as controls. After 12 wk, a greater vasoconstrictor response to electrical field stimulation (EFS) was observed in endothelium-intact and endothelium-denuded SMA of HF rats. Alpha-adrenoceptor antagonist phentolamine diminished this response in a higher magnitude in HF than in SO animals. However, the noradrenaline (NA) reuptake inhibitor desipramine increased EFS-induced vasoconstriction more in segments from HF rats. Besides, EFS-induced NA release was greater in HF animals, due to a higher tyrosine hydroxylase expression and activity. P2 purinoceptor antagonist suramin reduced EFS-induced vasoconstriction only in segments from SO rats, and adenosine 5'-triphosphate (ATP) release was lower in HF than in SO. Moreover, nitric oxide (NO) synthase inhibitor N^ω-nitro-L-arginine methyl ester (L-NAME) enhanced EFS-induced vasoconstriction in a similar extent in both groups. HF was not associated with changes in EFS-induced NO release or the vasodilator response to NO donor sodium nitroprusside. In conclusion, HF postmyocardial infarction enhanced noradrenergic function and diminished purinergic cotransmission in SMA and did not change nitrergic innervation. The net effect was an increased sympathetic participation on the EFS-induced vasoconstriction that could help to understand the neurotransduction involved on the control of vascular tonus in HF.NEW & NOTEWORTHY This study reinforces the pivotal role of noradrenergic innervation in the regulation of mesenteric vascular tone in a rat model of heart failure. Moreover, our results highlight the counteracting role of ATP and NA reuptake, and help to understand the signaling pathways involved on the control of vascular tonus and resistance in heart failure postmyocardial infarction.

Aortic Response to Strength Training and Spirulina platensis Dependent on Nitric Oxide and Antioxidants

Studies have shown that supplementation with Spirulina platensis improves vascular reactivity. However, it is unclear whether in association with strength training this effect can be enhanced. Thus, this study aimed to determine the effects of strength training and S. platensis on the reactivity of the aorta from Wistar rat and the possible mechanisms involved. The animals were supplemented with S. platensis and divided into sedentary (SG, SG50, SG150, and SG500) and trained groups (TG, TG50, TG150, and TG500). Nitrite, malondialdehyde (MDA) and antioxidant activity were determined by biochemical assays. To evaluate vascular response, cumulative concentration—response curves to phenylephrine (PHE) and acetylcholine (ACh) were constructed. L-NAME was used to assess the participation of nitric oxide (NO). It was observed that the PHE contractile potency was reduced in TG50, TG150, and TG500 groups compared to SG50, SG150, and SG500 groups, respectively. However, the presence of L-NAME increased the contractile response in all groups. Strength training potentiated the increase in relaxing activity induced by S. platensis, where the pCE₅₀ values of ACh increased in TG150 and TG500. These responses were accompanied by increased nitrite production, MDA reduction and increased antioxidant activity in the aorta of both TG150 and TG500 groups. Thus, the present study demonstrated that combined with strength training, S. platensis potentiates vascular improvement through the participation of NO and reduction of oxidative stress.

Chronic Exercise Improves Mitochondrial Function and Insulin Sensitivity in Brown Adipose Tissue

The aim of the present work was to study the consequences of chronic exercise training on factors involved in the regulation of mitochondrial remodeling and biogenesis, as well as the ability to produce energy and improve insulin sensitivity and glucose uptake in rat brown adipose tissue (BAT). Male Wistar rats were divided into two groups: (1) control group (C; n = 10) and (2) exercise-trained rats (ET; n = 10) for 8 weeks on a motor treadmill (five times per week for 50 min). Exercise training reduced body weight, plasma insulin, and oxidized LDL concentrations. Protein expression of ATP-independent metalloprotease (OMA1), short optic atrophy 1 (S-OPA1), and dynamin-related protein 1 (DRP1) in BAT increased in trained rats, and long optic atrophy 1 (L-OPA1) and mitofusin 1 (MFN1) expression decreased. BAT expression of nuclear respiratory factor type 1 (NRF1) and mitochondrial transcription factor A (TFAM), the main factors involved in mitochondrial biogenesis, was higher in trained rats compared to controls. Exercise training increased protein expression of sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) and AMP-activated protein kinase (pAMPK/AMPK ratio) in BAT. In addition, training increased carnitine palmitoyltransferase II (CPT II), mitochondrial F1 ATP synthase α-chain, mitochondrial malate dehydrogenase 2 (mMDH) and uncoupling protein (UCP) 1,2,3 expression in BAT. Moreover, exercise increased insulin receptor (IR) ratio (IRA/IRB ratio), IRA-insulin-like growth factor 1 receptor (IGF-1R) hybrids and p42/44 activation, and decreased IGF-1R expression and IR substrate 1 (p-IRS-1) (S307) indicating higher insulin sensitivity and favoring glucose uptake in BAT in response to chronic exercise training. In summary, the present study indicates that chronic exercise is able to improve the energetic profile of BAT in terms of increased mitochondrial function and insulin sensitivity.

Thyroid hormones affect nitrergic innervation function in rat mesenteric artery: Role of the PI3K/AKT pathway

We aimed to determine the influence of nitrergic innervation function on the decreased mesenteric arterial tone induced by high levels of triiodothyronine (T3), as a model of acute thyroiditis, as well as the mechanism/s implicated. We analysed in mesenteric segments from male Wistar rats the effect of 10 nmol/L T3 (2 h) on the vasomotor response to electrical field stimulation (EFS) in the presence/absence of specific neuronal NOS (nNOS) inhibitor L-NPA, or superoxide anion scavenger tempol. Nitric oxide (NO) release was measured in the presence/absence of tempol or PI3K inhibitor LY294002. Superoxide anion and peroxynitrite releases, nNOS, PI3K, AKT and superoxide dismutase (SOD) 1 and 2 expressions, nNOS and AKT phosphorylation, and SOD activity were analysed. T3 decreased EFS-induced vasoconstriction. L-NPA increased EFS-induced vasoconstriction more markedly in T3-incubated segments. T3 increased NO release. Tempol decreased EFS-induced vasoconstriction and augmented NO release only in segments without T3. LY294002 decreased NO release in T3-incubated segments. T3 diminished superoxide anion and peroxynitrite formation, enhanced SOD-2 expression, nNOS and AKT phosphorylations and SOD activity, and did not modify nNOS, PI3K, AKT and SOD-1 expressions. In conclusion, these results show a compensatory mechanism aimed at reducing the enhanced blood pressure that appears during acute thyroiditis.

Effects of a Single Bout of Resistance Exercise in Different Volumes on Endothelium Adaptations in Healthy Animals

Background:

Resistance exercise (RE) has been recommended for patients with cardiovascular diseases. Recently, a few studies have demonstrated that the intensity of a single bout of RE has an effect on endothelial adaptations to exercise. However, there is no data about the effects of different volumes of RE on endothelium function.

Objective:

The aim of the study was to evaluate the effects of different volumes of RE in a single bout on endothelium-dependent vasodilatation and nitric oxide (NO) synthesis in the mesenteric artery of healthy animals.

Methods:

Male Wistar rats were divided into three groups: Control (Ct); low-volume RE (LV, 5 sets x 10 repetitions) and high-volume RE (HV, 15 sets x 10 repetitions). The established intensity was 70% of the maximal repetition test. After the exercise protocol, rings of mesenteric artery were used for assessment of vascular reactivity, and other mesenteric arteries were prepared for detection of measure NO production by DAF-FM fluorescence. Insulin responsiveness on NO synthesis was evaluated by stimulating the vascular rings with insulin (10 nM).

Results:

The maximal relaxation response to insulin increased in the HV group only as compared with the Ct group. Moreover, the inhibition of nitric oxide synthesis (L-NAME) completely abolished the insulin-induced vasorelaxation in exercised rats. NO production showed a volume-dependent increase in the endothelial and smooth muscle layer. In endothelial layer, only Ct and LV groups showed a significant increase in NO synthesis when compared to their respective group under basal condition. On the other hand, in smooth muscle layer, NO fluorescence increased in all groups when compared to their respective group under basal condition.

Conclusions:

Our results suggest that a single bout of RE promotes vascular endothelium changes in a volume-dependent manner. The 15 sets x 10 repetitions exercise plan induced the greatest levels of NO synthesis.

Fundamentos:

O exercício resistido (ER) tem sido recomendado para pacientes com doenças cardiovasculares. Recentemente, alguns estudos demonstraram que a intensidade de uma sessão de ER exerce um efeito sobre a disfunção endotelial. No entanto, não há dados sobre os efeitos de diferentes volumes de ER sobre a função endotelial.

Objetivo:

O objetivo deste estudo foi avaliar os efeitos de diferentes volumes de ER, realizados em uma única sessão, sobre a vasodilatação dependente do endotélio e síntese de óxido nítrico (NO) em artéria mesentérica de animais saudáveis.

Métodos:

Ratos Wistar machos foram divididos em três grupos: Controle (Ct); baixo volume (BV, 5 séries x 10 repetições) e alto volume de ER (AV, 15 séries x 10 repetições). Foi estabelecida a intensidade de 70% do teste de repetição máxima. Após o protocolo de exercício, anéis de artéria mesentérica foram utilizados na avaliação da reatividade vascular, e outras artérias mesentéricas foram preparadas para a detecção da produção de NO por fluorescência com para do DAF-FM. A resposta à insulina pela síntese de NO foi avaliada estimulando-se os anéis vasculares com insulina (10nM).

Resultados:

A resposta máxima do relaxamento induzido por insulina foi aumentada somente no grupo AV em comparação ao grupo Ct. Além disso, a inibição da síntese do NO (L-NAME), aboliu completamente o relaxamento vascular induzido por insulina em ratos exercitados. A produção de NO mostrou um aumento dependente do volume no endotélio e no músculo liso. No endotélio, apenas os grupos Ct e BV mostraram aumento significativo na síntese de NO quando comparado aos seus respectivos grupos sob condição basal. No entanto, no músculo liso, a fluorescência foi aumentada em todos os grupos quando comparados aos seus respectivos grupos sob a condição basal.

Conclusões:

Nossos resultados sugerem que uma única sessão de ER foi capaz de promover adaptações no endotélio vascular. Além disso, nós observamos que este efeito é volume-dependente e o volume de 15 séries x10 repetições induziu o maior aumento na síntese de NO.

Beneficial and harmful effects of exercise in hypertensive patients: the role of oxidative stress

Oxidative stress has been implicated in the development and progression of hypertension. This review presents a comprehensive summary of original investigations focused on exercise-induced oxidative stress in hypertensive individuals. Single bouts of exercise can induce an acute state of oxidative stress. Chronic low-to-moderate exercise training improves the antioxidative defense and reduces the disease severity. However, the data that are currently available on the chronic intensive interval training-induced modification of the redox state in hypertensive patients are insufficient to draw adequate conclusions.

Aerobic exercise training protects against endothelial dysfunction by increasing nitric oxide and hydrogen peroxide production in LDL receptor-deficient mice

BACKGROUND

Endothelial dysfunction associated with hypercholesterolemia is an early event in atherosclerosis characterized by redox imbalance associated with high superoxide production and reduced nitric oxide (NO) and hydrogen peroxide (H2O2) production. Aerobic exercise training (AET) has been demonstrated to ameliorate atherosclerotic lesions and oxidative stress in advanced atherosclerosis. However, whether AET protects against the early mechanisms of endothelial dysfunction in familial hypercholesterolemia remains unclear. This study investigated the effects of AET on endothelial dysfunction and vascular redox status in the aortas of LDL receptor knockout mice (LDLr(-/-)), a genetic model of familial hypercholesterolemia.

METHODS

Twelve-week-old C57BL/6J (WT) and LDLr(-/-) mice were divided into sedentary and exercised (AET on a treadmill 1 h/5 × per week) groups for 4 weeks. Changes in lipid profiles, endothelial function, and aortic NO, H2O2 and superoxide production were examined.

RESULTS

Total cholesterol and triglycerides were increased in sedentary and exercised LDLr(-/-) mice. Endothelium-dependent relaxation induced by acetylcholine was impaired in aortas of sedentary LDLr(-/-) mice but not in the exercised group. Inhibition of NO synthase (NOS) activity or H2O2 decomposition by catalase abolished the differences in the acetylcholine response between the animals. No changes were noted in the relaxation response induced by NO donor sodium nitroprusside or H2O2. Neuronal NOS expression and endothelial NOS phosphorylation (Ser1177), as well as NO and H2O2 production, were reduced in aortas of sedentary LDLr(-/-) mice and restored by AET. Incubation with apocynin increased acetylcholine-induced relaxation in sedentary, but not exercised LDLr(-/-) mice, suggesting a minor participation of NADPH oxidase in the endothelium-dependent relaxation after AET. Consistent with these findings, Nox2 expression and superoxide production were reduced in the aortas of exercised compared to sedentary LDLr(-/-) mice. Furthermore, the aortas of sedentary LDLr(-/-) mice showed reduced expression of superoxide dismutase (SOD) isoforms and minor participation of Cu/Zn-dependent SODs in acetylcholine-induced, endothelium-dependent relaxation, abnormalities that were partially attenuated in exercised LDLr(-/-) mice.

CONCLUSION

The data gathered by this study suggest AET as a potential non-pharmacological therapy in the prevention of very early endothelial dysfunction and redox imbalance in familial hypercholesterolemia via increases in NO bioavailability and H2O2 production.

Increased Nitric Oxide Bioavailability and Decreased Sympathetic Modulation Are Involved in Vascular Adjustments Induced by Low-Intensity Resistance Training

Resistance training is one of the most common kind of exercise used nowadays. Long-term high-intensity resistance training are associated with deleterious effects on vascular adjustments. On the other hand, is unclear whether low-intensity resistance training (LI-RT) is able to induce systemic changes in vascular tone. Thus, we aimed to evaluate the effects of chronic LI-RT on endothelial nitric oxide (NO) bioavailability of mesenteric artery and cardiovascular autonomic modulation in healthy rats. Wistar animals were divided into two groups: exercised (Ex) and sedentary (SED) rats submitted to the resistance (40% of 1RM) or fictitious training for 8 weeks, respectively. After LI-RT, hemodynamic measurements and cardiovascular autonomic modulation by spectral analysis were evaluated. Vascular reactivity, NO production and protein expression of endothelial and neuronal nitric oxide synthase isoforms (eNOS and nNOS, respectively) were evaluated in mesenteric artery. In addition, cardiac superoxide anion production and ventricle morphological changes were also assessed. In vivo measurements revealed a reduction in mean arterial pressure and heart rate after 8 weeks of LI-RT. In vitro studies showed an increased acetylcholine (ACh)-induced vasorelaxation and greater NOS dependence in Ex than SED rats. Hence, decreased phenylephrine-induced vasoconstriction was found in Ex rats. Accordingly, LI-RT increased the NO bioavailability under basal and ACh stimulation conditions, associated with upregulation of eNOS and nNOS protein expression in mesenteric artery. Regarding autonomic control, LI-RT increased spontaneous baroreflex sensitivity, which was associated to reduction in both, cardiac and vascular sympathetic modulation. No changes in cardiac superoxide anion or left ventricle morphometric parameters after LI-RT were observed. In summary, these results suggest that RT promotes beneficial vascular adjustments favoring augmented endothelial NO bioavailability and reduction of sympathetic vascular modulation, without evidence of cardiac overload.

Aerobic exercise training increases nitrergic innervation function and decreases sympathetic innervation function in mesenteric artery from rats fed a high-fat diet

INTRODUCTION

We investigated whether high-fat diet (HFD)-induced obesity was associated with modifications in mesenteric innervation function, the mechanisms involved, and the possible effects of aerobic exercise training on these changes.

MATERIALS AND METHODS

Male Wistar rats were divided into three groups: rats fed a standard diet (control group); rats fed a HFD (35% fat) for 8 weeks; and HFD rats submitted to aerobic exercise training (8 weeks, 5 times per week for 50  min). Segments of isolated mesenteric arteries were exposed to electric field stimulation (EFS) with or without phentolamine, suramin, or Nω nitro-L-arginine methyl ester. Noradrenaline, ATP, and nitric oxide release, and total and phosphorylated neuronal nitric oxide synthase (nNOS, P-nNOS) expression were also measured.

RESULTS

EFS contraction was greater in sedentary HFD than in control rats. Phentolamine reduced EFS contractions more markedly in HFD rats. Suramin decreased EFS contractions only in control rats. Phentolamine + suramin practically abolished EFS-induced contraction in control rats, whereas it did not modify it in the HFD rats. Noradrenaline release was greater and ATP was lower in HFD rats. Nω nitro-L-arginine methyl ester increased contractions to EFS only in segments from control rats. Nitric oxide release and nNOS and P-nNOS expressions were lower in arterial segments from HFD rats than from control rats. None of these changes in sedentary HFD rats was present in the trained HFD rats.

CONCLUSIONS

Enhanced sympathetic and diminished nitrergic components contributed to increased vasoconstrictor responses to EFS in sedentary HFD rats. All these changes were avoided by aerobic exercise training, suggesting that aerobic exercise could reduce peripheral vascular resistance in obesity.

Effects of endurance, circuit, and relaxing training on cardiovascular risk factors in hypertensive elderly patients

Recommendations for prevention of cardiovascular diseases (CVDs) risk factors among older adults highlighted the importance of exercise-based interventions, including endurance training (ET). However, the evidence of efficacy of other interventions based on short-bouts of exercise (circuit training, CT), and the practice of breath-control and meditation (relaxing training, RT) is growing. The aim of this study was to elucidate if CT or RT are equally effective in CVD risk factors reduction compared to ET. To this purpose, in 40 elderly participants, with clinically diagnosed grade 1 hypertension, resting blood pressure, blood glucose, and cholesterol levels, peak oxygen uptake ([Formula: see text]), mechanical efficiency and quality of life were evaluated before and after 12 weeks of ET, CT, and RT treatments. Resting blood pressure reduced significantly in all groups by ∼11 %. In ET, blood cholesterol levels (-18 %), [Formula: see text] (+8 %), mechanical efficiency (+9 %), and quality of life scores (+36 %) ameliorated. In CT blood glucose levels (-11 %), [Formula: see text] (+7 %) and quality of life scores (+35 %) were bettered. Conversely, in RT, the lower blood pressure went along only with an improvement in the mental component of quality of life (+42 %). ET and CT were both appropriate interventions to reduce CVDs risk factors, because blood pressure reduction was accompanied by decreases in blood glucose and cholesterol levels, increases in [Formula: see text], mechanical efficiency, and quality of life. Although RT influenced only blood pressure and quality of life, this approach would be an attractive alternative for old individuals unable or reluctant to carry out ET or CT.

Alterations in perivascular innervation function in mesenteric arteries from offspring of diabetic rats

BACKGROUND AND PURPOSE

We have reported that exposure to a diabetic intrauterine environment during pregnancy increases blood pressure in adult offspring, but the mechanisms involved are not completely understood. This study was designed to analyse a possible role of perivascular sympathetic and nitrergic innervation in the superior mesenteric artery (SMA) in this effect.

EXPERIMENTAL APPROACH

Diabetes was induced in pregnant Wistar rats by a single injection of streptozotocin. Endothelium-denuded vascular rings from the offspring of control (O-CR) and diabetic rats (O-DR) were used. Vasomotor responses to electrical field stimulation (EFS), NA and the NO donor DEA-NO were studied. The expressions of neuronal NOS (nNOS) and phospho-nNOS (P-nNOS) and release of NA, ATP and NO were determined. Sympathetic and nitrergic nerve densities were analysed by immunofluorescence.

KEY RESULTS

Blood pressure was higher in O-DR animals. EFS-induced vasoconstriction was greater in O-DR animals. This response was decreased by phentolamine more in O-DR animals than their controls. L-NAME increased EFS-induced vasoconstriction more strongly in O-DR than in O-CR segments. Vasomotor responses to NA or DEA-NO were not modified. NA, ATP and NO release was increased in segments from O-DR. nNOS expression was not modified, whereas P-nNOS expression was increased in O-DR. Sympathetic and nitrergic nerve densities were similar in both experimental groups.

CONCLUSIONS AND IMPLICATIONS

The activity of sympathetic and nitrergic innervation is increased in SMA from O-DR animals. The net effect is an increase in EFS-induced contractions in these animals. These effects may contribute to the increased blood pressure observed in the offspring of diabetic rats.

Endothelial and Neuronal Nitric Oxide Activate Distinct Pathways on Sympathetic Neurotransmission in Rat Tail and Mesenteric Arteries

Nitric oxide (NO) seems to contribute to vascular homeostasis regulating neurotransmission. This work aimed at assessing the influence of NO from different sources and respective intracellular pathways on sympathetic neurotransmission, in two vascular beds. Electrically-evoked [³H]-noradrenaline release was assessed in rat mesenteric and tail arteries in the presence of NO donors or endothelial/neuronal nitric oxide synthase (NOS) inhibitors. The influence of NO on adenosine-mediated effects was also studied using selective antagonists for adenosine receptors subtypes. Location of neuronal NOS (nNOS) was investigated by immunohistochemistry (with specific antibodies for nNOS and for Schwann cells) and Confocal Microscopy. Results indicated that: 1) in mesenteric arteries, noradrenaline release was reduced by NO donors and it was increased by nNOS inhibitors; the effect of NO donors was only abolished by the adenosine A₁ receptors antagonist; 2) in tail arteries, noradrenaline release was increased by NO donors and it was reduced by eNOS inhibitors; adenosine receptors antagonists were devoid of effect; 3) confocal microscopy showed nNOS staining in adventitial cells, some co-localized with Schwann cells. nNOS staining and its co-localization with Schwann cells were significantly lower in tail compared to mesenteric arteries. In conclusion, in mesenteric arteries, nNOS, mainly located in Schwann cells, seems to be the main source of NO influencing perivascular sympathetic neurotransmission with an inhibitory effect, mediated by adenosine A₁ receptors activation. Instead, in tail arteries endothelial NO seems to play a more relevant role and has a facilitatory effect, independent of adenosine receptors activation.

Alterations in perivascular sympathetic and nitrergic innervation function induced by late pregnancy in rat mesenteric arteries

Background and Purpose

We investigated whether pregnancy was associated with changed function in components of perivascular mesenteric innervation and the mechanism/s involved.

Experimental Approach

We used superior mesenteric arteries from female Sprague-Dawley rats divided into two groups: control rats (in oestrous phase) and pregnant rats (20 days of pregnancy). Modifications in the vasoconstrictor response to electrical field stimulation (EFS) were analysed in the presence/absence of phentolamine (alpha-adrenoceptor antagonist) or L-NAME (nitric oxide synthase-NOS- non-specific inhibitor). Vasomotor responses to noradrenaline (NA), and to NO donor DEA-NO were studied, NA and NO release measured and neuronal NOS (nNOS) expression/activation analysed.

Key Results

EFS induced a lower frequency-dependent contraction in pregnant than in control rats. Phentolamine decreased EFS-induced vasoconstriction in segments from both experimental groups, but to a greater extent in control rats. EFS-induced vasoconstriction was increased by L-NAME in arteries from both experimental groups. This increase was greater in segments from pregnant rats. Pregnancy decreased NA release while increasing NO release. nNOS expression was not modified but nNOS activation was increased by pregnancy. Pregnancy decreased NA-induced vasoconstriction response and did not modify DEA-NO-induced vasodilation response.

Conclusions and Implications

Neural control of mesenteric vasomotor tone was altered by pregnancy. Diminished sympathetic and enhanced nitrergic components both contributed to the decreased vasoconstriction response to EFS during pregnancy. All these changes indicate the selective participation of sympathetic and nitrergic innervations in vascular adaptations produced during pregnancy.

Impact of exercise training on redox signaling in cardiovascular diseases

Reactive oxygen and nitrogen species regulate a wide array of signaling pathways that governs cardiovascular physiology. However, oxidant stress resulting from disrupted redox signaling has an adverse impact on the pathogenesis and progression of cardiovascular diseases. In this review, we address how redox signaling and oxidant stress affect the pathophysiology of cardiovascular diseases such as ischemia-reperfusion injury, hypertension and heart failure. We also summarize the benefits of exercise training in tackling the hyperactivation of cellular oxidases and mitochondrial dysfunction seen in cardiovascular diseases.

Opposite effect of mast cell stabilizers ketotifen and tranilast on the vasoconstrictor response to electrical field stimulation in rat mesenteric artery

OBJECTIVES

We analyzed whether mast cell stabilization by either ketotifen or tranilast could alter either sympathetic or nitrergic innervation function in rat mesenteric arteries.

METHODS

Electrical field stimulation (EFS)-induced contraction was analyzed in mesenteric segments from 6-month-old Wistar rats in three experimental groups: control, 3-hour ketotifen incubated (0.1 αmol/L), and 3-hour tranilast incubated (0.1 mmol/L). To assess the possible participation of nitrergic or sympathetic innervation, EFS contraction was analyzed in the presence of non-selective nitric oxide synthase (NOS) inhibitor L-NAME (0.1 mmol/L), α-adrenergic receptor antagonist phentolamine (0.1 µmol/L), or the neurotoxin 6-hydroxydopamine (6-OHDA, 1.46 mmol/L). Nitric oxide (NO) and superoxide anion (O2.(-) levels were measured, as were vasomotor responses to noradrenaline (NA) and to NO donor DEA-NO, in the presence and absence of 0.1 mmol/L tempol. Phosphorylated neuronal NOS (P-nNOS) expression was also analyzed.

RESULTS

EFS-induced contraction was increased by ketotifen and decreased by tranilast. L-NAME increased the vasoconstrictor response to EFS only in control segments. The vasodilator response to DEA-NO was higher in ketotifen- and tranilast-incubated segments, while tempol increased vasodilator response to DEA-NO only in control segments. Both NO and O2(-) release, and P-nNOS expression were diminished by ketotifen and by tranilast treatment. The decrease in EFS-induced contraction produced by phentolamine was lower in tranilast-incubated segments. NA vasomotor response was decreased only by tranilast. The remnant vasoconstriction observed in control and ketotifen-incubated segments was abolished by 6-OHDA.

CONCLUSION

While both ketotifen and tranilast diminish nitrergic innervation function, only tranilast diminishes sympathetic innnervation function, thus they alter the vasoconstrictor response to EFS in opposing manners.