Oxidative stress and nitric oxide synthase in skeletal muscles of rats with post-infarction, compensated chronic heart failure

NOS3 Polymorphisms Can Influence the Effect of Multicomponent Training on Blood Pressure, Nitrite Concentration and Physical Fitness in Prehypertensive and Hypertensive Older Adult Women

Associations of endothelial nitric oxide synthase (NOS3) polymorphisms with hypertension and response to exercise training in prehypertensive and hypertensive older adult women remain unclear. This study used a multicomponent program (various capacities and motor skills) in the physical training intervention. It analyzed the influence of NOS3 polymorphisms [−786T > C, 894G > T (Glu298Asp), and intron 4b/a] on the response of blood pressure (BP), nitrite concentration, and physical fitness in older adult women. Fifty-two participants aged between 50 and 80 underwent body mass index, BP, 6-min walk, elbow flexion, and sit and stand-up tests to assess physical fitness. The intervention duration was 12 weeks, twice a week, on non-consecutive days. Each session lasted 90 min, maintaining an intensity between 13 (moderate) and 15 (intense), controlled by the Subjective Effort Perception Scale. Plasma/blood samples were collected to assess nitrite concentration and genotyping. The statistical analysis included Fisher’s exact test and linear mixed-effects models. The multicomponent training’s positive effect was observed with a similar response in both prehypertensive and hypertensive groups. However, carriers of different genotypes demonstrated different responses to training: the decreases in systolic and diastolic BP and increases in nitrite expected from the physical training were smaller in variant genotype than ancestral genotype carriers, especially in the hypertensive group. At positions −786T > C and Glu298Asp, only the ancestral genotypes showed a decrease in diastolic BP (Δ% = −8.1, and Δ% = −6.5, respectively) and an increase on nitrite (Δ% = 19.1, and Δ% = 24.1, respectively) in the hypertensive group. Our results show that the benefits of a multicomponent training intervention seem to be genotype-dependent. It should be possible to consider genetic variants when selecting an exercise treatment intervention.

Multicomponent Training Changes Blood Pressure and Redox Status in Older Women: Influence of β2 Adrenergic Receptor Haplotypes

The β2 adrenergic receptor (β2-AR) plays an important role in vascular smooth muscle. However, the interaction between Arg16Gly and Gln27Glu β2-AR polymorphisms, and exercise training has not yet been established. This study evaluated the influence of these β2-AR polymorphisms on body composition, aerobic capacity, blood pressure, lipid profile, nitric oxide, and redox status at baseline and in response to an exercise program in women aged 50-79 years. Genotype and haplotypes were analyzed in association with the previously mentioned variables before and after the multicomponent training (12 weeks, 2 sessions/week, 90 min/session, and exercise intensity between 13 and 15 on the Borg scale). Individuals who carry β2-AR Arg16Arg/Gln27Gln genotypes presented more improvements in blood pressure, body composition, aerobic capacity, and redox status in response to a multicomponent training program compared with individuals who do not carry this haplotype. In some years, the genetic profile may be used to predict which exercise program can induce more health benefits for each person.

Neuronal nitric oxide synthase regulation of skeletal muscle functional hyperemia: exercise training and moderate compensated heart failure

Nitric oxide (NO) modulates oxygen delivery-utilization matching in resting and contracting skeletal muscle. Recent reports indicate that neuronal NO synthase (nNOS)-mediated vasoregulation during contractions is enhanced with exercise training and impaired with chronic heart failure (HF). Consequently, we tested the hypothesis that selective nNOS inhibition (S-methyl-l-thiocitrulline; SMTC, 2.1 μmol/kg) would produce attenuated reductions in muscle blood flow during moderate/heavy submaximal exercise in sedentary HF rats compared to their healthy counterparts. In addition, SMTC was expected to evoke greater reductions in exercising muscle blood flow in trained compared to sedentary healthy and HF rats. Blood flow during submaximal treadmill running (20 min/m, 5% grade) was determined via radiolabeled microspheres pre- and post-SMTC administration in healthy sedentary (Healthy + Sed, n = 8), healthy exercise trained (Healthy + ExT, n = 8), HF sedentary (HF + Sed, left ventricular end-diastolic pressure (LVEDP) = 12 ± 1 mmHg, n = 8), and HF exercise trained (HF + ExT, LVEDP = 16 ± 2 mmHg, n = 7) rats. nNOS contribution to exercising total hindlimb blood flow (ml/min/100 g) was not increased by training in either healthy or HF groups (Healthy + Sed: 105 ± 11 vs. 108 ± 16; Healthy + ExT: 96 ± 9 vs. 91 ± 7; HF + Sed: 124 ± 6 vs. 110 ± 12; HF + ExT: 107 ± 13 vs. 101 ± 8; control vs. SMTC, respectively; p > .05 for all). Similarly, SMTC did not reduce exercising blood flow in the majority of individual hindlimb muscles in any group (p > .05 for all, except for the semitendinosus and adductor longus in HF + Sed and the adductor longus in HF + ExT; p < .05). Contrary to our hypothesis, we find no support for either upregulation of nNOS function contributing to exercise hyperemia after training or its dysregulation with chronic HF.

Effects of l-arginine supplementation associated with continuous or interval aerobic training on chronic heart failure rats

OBJECTIVE

Chronic heart failure (CHF) is related with exercise intolerance and impaired nitric oxide (NO) production, which can lead to several functional capacity alterations. Considering the possible superiority of aerobic interval training compared to continuous training and the capacity of l-arginine to restore the NO pathway, the aim of the present study was to investigate whether these treatments are beneficial to exercise capacity, muscle mass preservation and hemodynamic, inflammatory and oxidative stress parameters in CHF rats.

METHODS

Thirty-eight male Wistar rats post 6weeks of myocardial infarction (MI) surgery were randomly assigned into 6 CHF groups: sedentary (SED, n=6); SED+Arg (n=7); ACT (n=8); ACT+Arg (n=5); AIT (n=7); AIT+Arg (n=5). Exercise test capacity (ETC) was performed pre and post 8weeks of intervention. Supplemented rats received Arg (1g/kg) by oral gavage (7×/week). Exercise training was performed on a rat treadmill (5×/week). Hemodynamic variables, tissue collection, congestion, inflammatory cytokines, and oxidative parameters were evaluated at the end of protocols.

RESULTS

All trained groups showed a superior exercise capacity compared to SED groups on the post-intervention test (p<0.0001). Pulmonary congestion was attenuated in AIT and AIT+Arg compared with the SED group (p<0.05). Left ventricular end-diastolic pressure (LVEDP) was lower in ACT+Arg, AIT, and AIT+Arg groups than SED group (p<0.05). Association of AIT with Arg supplementation was able to improve hemodynamic responses (left ventricular systolic pressure (LVSP), systolic blood pressure (SBP), +dP/dt_max, and -dP/dt_max (p<0.05), likewise, decrease muscular and renal lipid peroxidation and tumor necrosis factor (TNF)-α, and increase interleukin (IL)-10/TNF-α plasmatic levels (p<0.01). Groups that associated aerobic exercise with Arg supplementation (ACT+Arg and AIT+Arg) revealed higher gastrocnemius mass compared to the SED group (p<0.01).

CONCLUSIONS

Both aerobic training protocols were capable to improve aerobic capacity, and the association with Arg supplementation was important to attenuate muscle loss. Moreover, interval training associated with Arg supplementation elicits greater improvements in hemodynamic parameters, contributing to reduction in pulmonary congestion, and demonstrated particular responses in the inflammatory profile and in the antioxidant status.

Effect of Multicomponent Training on Blood Pressure, Nitric Oxide, Redox Status, and Physical Fitness in Older Adult Women: Influence of Endothelial Nitric Oxide Synthase (NOS3) Haplotypes

The purpose of this study was to verify the influence of the genotype or haplotype (interaction) of the NOS3 polymorphisms [-786T>C, 894G>T (Glu298Asp), and intron 4b/a] on the response to multicomponent training (various capacities and motor skills) on blood pressure (BP), nitrite concentration, redox status, and physical fitness in older adult women. The sample consisted of 52 participants, who underwent body mass index and BP assessments. Physical fitness was evaluated by six-minute walk, elbow flexion, and sit and stand up tests. Plasma/blood samples were used to evaluate redox status, nitrite concentration, and genotyping. Associations were observed between isolated polymorphisms and the response of decreased systolic and diastolic BP and increased nitrite concentration and antioxidant activity. In the haplotype analysis, the group composed of ancestral alleles (H1) was the only one to present improvement in all variables studied (decrease in systolic and diastolic BP, improvement in nitrite concentration, redox status, and physical fitness), while the group composed of variant alleles (H8) only demonstrated improvement in some variables of redox status and physical fitness. These findings suggest that NOS3 polymorphisms and physical training are important interacting variables to consider in evaluating redox status, nitric oxide availability and production, and BP control.

Maternal nicotine exposure leads to decreased cardiac protein disulfide isomerase and impaired mitochondrial function in male rat offspring

Smoking throughout pregnancy can lead to complications during gestation, parturition and neonatal development. Thus, nicotine replacement therapies are a popular alternative thought to be safer than cigarettes. However, recent studies in rodents suggest that fetal and neonatal nicotine exposure alone results in cardiac dysfunction and high blood pressure. While it is well known that perinatal nicotine exposure causes increased congenital abnormalities, the mechanisms underlying longer-term deficits in cardiac function are not completely understood. Recently, our laboratory demonstrated that nicotine impairs placental protein disulfide isomerase (PDI) triggering an increase in endoplasmic reticulum stress, leading us to hypothesize that this may also occur in the heart. At 3 months of age, nicotine-exposed offspring had 45% decreased PDI levels in the absence of endoplasmic reticulum stress. Given the association of PDI and superoxide dismutase enzymes, we further observed that antioxidant superoxide dismutase-2 levels were reduced by 32% in these offspring concomitant with a 26-49% decrease in mitochondrial complex proteins (I, II, IV and V) and tissue inhibitor of metalloproteinase-4, a critical matrix metalloprotease for cardiac contractility and health. Collectively, this study suggests that perinatal nicotine exposure decreases PDI, which can promote oxidative damage and mitochondrial damage, associated with a premature decline in cardiac function.

Influence of Estimated Training Status on Anti and Pro-Oxidant Activity, Nitrite Concentration, and Blood Pressure in Middle-Aged and Older Women

The purpose of this study was to compare the association between anti and pro-oxidant activity, nitrite concentration, and blood pressure (BP) in middle-aged and older women with different levels of estimated training status (TS). The sample consisted of 155 females (50-84 years) who were submitted to a physical examination to evaluate estimated TS through the "Functional Fitness Battery Test," BP measurements, and plasma blood samples to evaluate pro-oxidant and antioxidant activity and nitrite concentrations. Participants were separated by age into a middle-aged group (<65 years) and an older (≥65 years) group and then subdivided in each group according to TS. Blood biochemistry was similar between groups. On the other hand, protein oxidation was lower in participants with higher TS, independent of age. Older females with higher TS presented higher nitrite concentrations, lower lipoperoxidation, and lower values of BP compared with those with lower TS. Lower GPx activity was observed in participants with higher TS compared with middle-aged with lower TS. Thus, our results suggest that good levels of TS may be associated with lower oxidative stress and higher nitrite concentration and may contribute to maintain normal or reduced blood pressure values.

Training Status as a Marker of the Relationship between Nitric Oxide, Oxidative Stress, and Blood Pressure in Older Adult Women

The purpose of this study was to evaluate the influence of functional fitness and oxidative capacity on the nitric oxide concentration associated with hemodynamic control in older adult women. The sample consisted of 134 women (65.73 ± 6.14 years old). All subjects underwent a physical examination to assess body mass index, waist-hip ratio, body fat measurement by dual energy X-ray absorptiometry, and blood pressure (BP). Training status (TS) was evaluated by indirect determination of maximal oxygen uptake by a treadmill test using Balke protocol modified for older adults. Functional fitness was also evaluated through a “Functional Fitness Battery Test” to determine the general fitness functional index (GFFI). All participants were separated according to the functional fitness (TS1, very weak and weak; TS2, regular; TS3, good and very good). Plasma blood samples were used to evaluate prooxidant and antioxidant activity and nitrite and nitrate concentrations. The general results of this study showed that good levels of TS were related to lower levels of lipoperoxidation and protein damage, higher levels of antioxidant, and higher concentration of nitrite and nitrate. This combination may be responsible for the lower levels of BP in subjects with better TS.

Ultrasound modulates skeletal muscle cytokine levels in rats with heart failure

Heart failure is a multisystemic disorder that leads to an imbalance between pro- and anti-inflammatory cytokines. Therapeutic ultrasound (TU) has been reported to modulate the inflammatory process. The aim of this study was to evaluate the effect of TU on pro- and anti-inflammatory cytokine levels in soleus muscle and plasma of rats with heart failure. Thirty male Wistar rats (230-260 g) were submitted to ligation of the left coronary artery or sham surgery. Six weeks after surgery, TU was administered directly to the right lower limb. The results indicate that TU promotes reduction of pro-inflammatory cytokine levels (tumor necrosis factor α, interleukin-6) and increases anti-inflammatory cytokine levels (interleukin-10) in the soleus muscle of rats with heart failure. This is the first study to find that TU can modulate cytokine levels in rats with heart failure. Additionally, this is a first report that TU can modulate interleukin-10 levels in the soleus muscle.

N-acylhydrazone improves exercise intolerance in rats submitted to myocardial infarction by the recovery of calcium homeostasis in skeletal muscle

AIMS

This work investigated the effects of 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294) treatment on the contractile response of soleus (SOL) muscle from rats submitted to myocardial infarction (MI).

MAIN METHODS

Following coronary artery ligation, LASSBio-294 (2mg/kg, i.p.) or vehicle was administrated once daily for 4 weeks.

KEY FINDINGS

The run time to fatigue for sham rats was 17.9 ±2.6 min, and it was reduced to 3.3 ± 0.8 min (P<0.05) in MI rats. In MI rats treated with LASSBio-294, the time to fatigue was 15.1 ± 3.6 min. During the contractile test, SOL muscles from sham rats showed a response of 7.12 ± 0.54N/cm(2) at 60 Hz, which was decreased to 5.45 ± 0.49 N/cm(2) (P<0.05) in MI rats. The contractility of SOL muscles from the MI-LASSBio-294 group was increased to 9.01 ± 0.65N/cm(2). At 16 mM caffeine, the contractility was reduced from 2.31 ± 0.33 to 1.60 ± 0.21 N/cm(2) (P<0.05) in the MI group. In SOL muscles from MI-LASSBio-294 rats, the caffeine response was increased to 2.62 ± 0.33 N/cm(2). Moreover, SERCA2a expression in SOL muscles was decreased by 0.31-fold (31%) in the MI group compared to the Sham group (P<0.05). In the MI-LASSBio-294 group, it was increased by 1.53-fold (153%) compared to the MI group (P<0.05). Meanwhile, the nuclear density in SOL muscles was increased in the MI group compared to the Sham group. Treatment with LASSBio-294 prevented this enhancement of cellular infiltrate.

SIGNIFICANCE

LASSBio-294 treatment prevented the development of muscular fatigue and improved exercise intolerance in rats submitted to MI.

The relationship between training status, blood pressure and uric acid in adults and elderly

Background

Hypertension can be generated by a great number of mechanisms including elevated uric acid (UA) that contribute to the anion superoxide production. However, physical exercise is recommended to prevent and/or control high blood pressure (BP). The purpose of this study was to investigate the relationship between BP and UA and whether this relationship may be mediated by the functional fitness index.

Methods

All participants (n = 123) performed the following tests: indirect maximal oxygen uptake (VO₂max), AAHPERD Functional Fitness Battery Test to determine the general fitness functional index (GFFI), systolic and diastolic blood pressure (SBP and DBP), body mass index (BMI) and blood sample collection to evaluate the total-cholesterol (CHOL), LDL-cholesterol (LDL-c), HDL-cholesterol (HDL-c), triglycerides (TG), uric acid (UA), nitrite (NO2) and thiobarbituric acid reactive substances (T-BARS). After the physical, hemodynamic and metabolic evaluations, all participants were allocated into three groups according to their GFFI: G1 (regular), G2 (good) and G3 (very good).

Results

Baseline blood pressure was higher in G1 when compared to G3 (+12% and +11%, for SBP and DBP, respectively, p<0.05) and the subjects who had higher values of BP also presented higher values of UA. Although UA was not different among GFFI groups, it presented a significant correlation with GFFI and VO₂max. Also, nitrite concentration was elevated in G3 compared to G1 (140±29 μM vs 111± 29 μM, for G3 and G1, respectively, p<0.0001). As far as the lipid profile, participants in G3 presented better values of CHOL and TG when compared to those in G1.

Conclusions

Taking together the findings that subjects with higher BP had elevated values of UA and lower values of nitrite, it can be suggested that the relationship between blood pressure and the oxidative stress produced by acid uric may be mediated by training status.

Effects of chronic heart failure on neuronal nitric oxide synthase-mediated control of microvascular O2 pressure in contracting rat skeletal muscle

Chronic heart failure (CHF) impairs nitric oxide (NO)-mediated regulation of the skeletal muscle microvascular O(2) delivery/V(O(2)) ratio (which sets the microvascular O(2) pressure, PO(2)mv). Given the pervasiveness of endothelial dysfunction in CHF, this NO-mediated dysregulation is attributed generally to eNOS. It is unknown whether nNOS-mediated PO(2)mv regulation is altered in CHF. We tested the hypothesis that CHF impairs nNOS-mediated PO(2)mv control. In healthy and CHF (left ventricular end diastolic pressure (LVEDP): 6 ± 1 versus 14 ± 1 mmHg, respectively, P < 0.05) rats spinotrapezius muscle blood flow (radiolabelled microspheres), PO(2)mv (phosphorescence quenching), and V(O(2)) (Fick calculation) were measured before and after 0.56 mg kg(-1)i.a. of the selective nNOS inhibitor S-methyl-l-thiocitrulline (SMTC). In healthy rats, SMTC increased baseline PO(2)mv (

CONTROL

29.7 ± 1.4, SMTC: 34.4 ± 1.9 mmHg, P < 0.05) by reducing V(O(2)) (↓20%) without any effect on blood flow and speeded the mean response time (MRT, time to reach 63% of the overall kinetics response,

CONTROL

24.2 ± 2.0, SMTC: 18.5 ± 1.3 s, P < 0.05). In CHF rats, SMTC did not alter baseline PO(2)mv (

CONTROL

25.7 ± 1.6, SMTC: 28.6 ± 2.1 mmHg, P > 0.05), V(O(2)) at rest, or the MRT (CONTROL: 22.8 ± 2.6, SMTC: 21.3 ± 3.0 s, P > 0.05). During the contracting steady-state, SMTC reduced blood flow (↓15%) and V(O(2)) (↓15%) in healthy rats such that PO(2)mv was unaltered (

CONTROL

19.8 ± 1.7, SMTC: 20.7 ± 1.8 mmHg, P > 0.05). In marked contrast, in CHF rats SMTC did not change contracting steady-state blood flow, V(O(2)), or PO(2)mv (

CONTROL

17.0 ± 1.4, SMTC: 17.7 ± 1.8 mmHg, P > 0.05). nNOS-mediated control of skeletal muscle microvascular function is compromised in CHF versus healthy rats. Treatments designed to ameliorate microvascular dysfunction in CHF may benefit by targeting improvements in nNOS function.

Novel biomarkers of bladder decompensation after partial bladder obstruction

AIMS

Partial bladder outlet obstruction (PBOO) results in marked contractile, biochemical, and histological alterations in the bladder. Our aim was to determine the time course of progressive PBOO in the rabbit and to find parameters that marked the shift to decompensation.

MATERIALS AND METHODS

Twenty-four rabbits were subjected to 1, 2, 4, and 8 weeks of PBOO. Sham operated rabbits served as controls. At each time period, cystometry was performed and individual bladder strips were used for contractility studies. Full-thickness sections of bladder body from each rabbit were fixed in formalin and used to determine the vascular density and nerve density. The balance of the bladder body was separated between muscle and mucosa and was analyzed for superoxide dismutase (SOD) and catalase (CAT) activities.

RESULTS

Bladder weight increased progressively and all contractile responses were reduced significantly over the course of obstruction. Markedly increased bladder weight and very large bladder volumes indicated decompensation. Nerve density was marked decreased in decompensated bladders. Similarly, SOD activity in muscle decreased progressively and was markedly lower in decompensated bladders. Although CAT activity of the muscle increased after 2-4 weeks of obstruction, it decreased markedly in decompensated bladders.

CONCLUSION

This study shows that prolonged PBOO causes progressive deterioration in the rabbit bladder with decompensation after 8 weeks. Markedly decreased nerve density and severely reduced SOD and CAT activities are associated with the shift from compensated to decompensated function of the bladder. They may be excellent biomarkers of decompensation.

Effects of Congestive Heart Failure on Ca 2+ Handling in Skeletal Muscle During Fatigue

Skeletal muscle weakness and decreased exercise capacity are major symptoms reported by patients with congestive heart failure (CHF). Intriguingly, these skeletal muscle symptoms do not correlate with the decreased heart function. This suggests that CHF leads to maladaptive changes in skeletal muscles, and as reported most markedly in slow-twitch muscles. We used rats at 6 weeks after infarction to measure expression of key proteins involved in SR Ca 2+ release and uptake in slow-twitch soleus muscles. We also measured force and myoplasmic free [Ca 2+ ] ([Ca 2+ ] i ) in intact single fibers of soleus muscles. CHF rats showed clear signs of severe cardiac dysfunction with marked increases in heart weight and left ventricular end-diastolic pressure compared with sham operated rats (Sham). There were small, but significant, changes in the content of proteins involved in cellular Ca 2+ handling in CHF muscles: slight increases in SR Ca 2+ release channels (ie, the ryanodine receptors) and in SR Ca 2+ -ATPase. Tetanic force and [Ca 2+ ] i were not significantly different between CHF and Sham soleus fibers under resting conditions. However, during the stimulation period there was a decrease in tetanic force without changes in [Ca 2+ ] i in CHF fibers that was not observed in Sham fibers. The fatigue-induced changes recovered rapidly. We conclude that CHF soleus fibers fatigue more rapidly than Sham fibers because of a reversible fatigue-induced decrease in myofibrillar function.