Effects of exercise-induced oxidative stress on nitric oxide release and antioxidant activity

The Association of Self-Reported Muscle-Strengthening Activities With Carotid Intima-Media Thickness in Older Adults: Cooper Center Longitudinal Study

The purpose of the current investigation was to examine the cross-sectional associations of participation in muscle-strengthening activities (MSAs) with carotid intima-media thickness (CIMT) among older adults. The data are from 2,557 older adult participants enrolled in an observational cohort who reported no history of cardiovascular disease. MSA was determined using a questionnaire. Carotid ultrasound was performed to measure the CIMT of the common carotid artery bilaterally. Logistic regression models were constructed to estimate the association of MSA with CIMT after adjustment for potential confounders. The participants were aged 68.6 ± 7.0 years, and the majority were male (71.7%) and White (96.5%); 18% had abnormal CIMT. Meeting the physical activity guidelines for MSA was inversely associated with abnormal CIMT after adjustment for age and sex. However, this observed inverse relation became statistically null after further adjustment for cardiovascular disease risk factors, including aerobic physical activity.

Vigorous exercise training improves reactivity of cerebral arterioles and reduces brain injury following transient focal ischemia

OBJECTIVE

Our objective was to examine whether vigorous exercise training (VExT) could influence nitric oxide synthase (NOS)-dependent vasodilation and transient focal ischemia-induced brain injury. Rats were divided into sedentary (SED) or VExT groups.

MATERIALS AND METHODS

Exercise was carried out 5 days/week for a period of 8-10 weeks. First, we measured responses of pial arterioles to an eNOS-dependent (ADP), an nNOS-dependent (NMDA) and a NOS-independent (nitroglycerin) agonist in SED and VExT rats. Second, we measured infarct volume in SED and VExT rats following middle cerebral artery occlusion (MCAO). Third, we measured superoxide levels in brain tissue of SED and VExT rats under basal and stimulated conditions.

RESULTS

We found that eNOS- and nNOS-dependent, but not NOS-independent vasodilation, was increased in VExT compared to SED rats, and this could be inhibited with L-NMMA in both groups. In addition, we found that VExT reduced infarct volume following MCAO when compared to SED rats. Further, superoxide levels were similar in brain tissue from SED and VExT rats under basal and stimulated conditions.

CONCLUSIONS

We suggest that VExT potentiates NOS-dependent vascular reactivity and reduces infarct volume following MCAO via a mechanism that appears to be independent of oxidative stress, but presumably related to an increase in the contribution of nitric oxide.

Influence of exercise training on ischemic brain injury in type 1 diabetic rats

While exercise training (ExT) appears to influence cerebrovascular function during type 1 diabetes (T1D), it is not clear whether this beneficial effect extends to protecting the brain from ischemia-induced brain injury. Thus our goal was to examine whether modest ExT could influence transient focal ischemia-induced brain injury along with nitric oxide synthase (NOS)-dependent dilation of cerebral (pial) arterioles during T1D. Sprague-Dawley rats were divided into four groups: nondiabetic sedentary, nondiabetic ExT, diabetic (streptozotocin; 50 mg/kg ip) sedentary, and diabetic ExT. In the first series of studies, we measured infarct volume in all groups of rats following right MCA occlusion for 2 h, followed by 24 h of reperfusion. In a second series of studies, a craniotomy was performed over the parietal cortex, and we measured responses of pial arterioles to an endothelial NOS (eNOS)-dependent, a neuronal NOS (nNOS)-dependent, and a NOS-independent agonist in all groups of rats. We found that sedentary diabetic rats had significantly larger total, cortical, and subcortical infarct volumes following ischemia-reperfusion than sedentary nondiabetic, nondiabetic ExT, and diabetic ExT rats. Infarct volumes were similar in sedentary nondiabetic, ExT nondiabetic, and ExT diabetic rats. In contrast, ExT did not alter infarct size in nondiabetic compared with sedentary nondiabetic rats. In addition, ExT diabetic rats had impaired eNOS- and nNOS-dependent, but not NOS-independent, vasodilation that was restored by ExT. Thus ExT of T1D rats lessened ischemic brain injury following middle cerebral artery occlusion and restored impaired eNOS- and nNOS-dependent vascular function. Since the incidence of ischemic stroke is increased during T1D, we suggest that our finding are significant in that modest ExT may be a viable preventative therapeutic approach to lessen ischemia-induced brain injury that may occur in T1D subjects.

The effects of progressive exercise on cardiovascular function in elite athletes: focus on oxidative stress

Some side-effects of excessive physical training are ascribed to reactive oxygen species production. In this work we investigated the effects of progressively imposed maximal physical effort (levels I to V), using progressive maximal exercise test, on peripheral blood lactate, NO (through NO2-), superoxide anion (O2-) and methemoglobin (MetHb) in a group of 19 elite soccer players. Blood lactate (mmol/L) was increased (4.55, level V vs. resting level, 1.95). The basal production of NO2- was in the direct relation with O2 consumption. Significant increase (p<0.05) in O2- values at effort level I (4.18) as compared to the resting value (4.01), and the significant increase (p<0.01 or p<0.05) in the MetHb (%) was found between II (18.79) and III (19.63) or between II and IV (19.24) effort levels, respectively. The regression lines of NO2- and O2- crossed at the level of the respiratory compensation point (RC), suggesting that RC could be of a crucial importance not only in the anaerobic and aerobic metabolism but in mechanisms of signal transductions as well. The results could be of the theoretical interest and also useful in designing an athlete training strategy.

Exercise training normalizes impaired NOS-dependent responses of cerebral arterioles in type 1 diabetic rats

Our goal was to examine whether exercise training (ExT) could normalize impaired nitric oxide synthase (NOS)-dependent dilation of cerebral (pial) arterioles during type 1 diabetes (T1D). We measured the in vivo diameter of pial arterioles in sedentary and exercised nondiabetic and diabetic rats in response to an endothelial NOS (eNOS)-dependent (ADP), an neuronal NOS (nNOS)-dependent [N-methyl-D-aspartate (NMDA)], and a NOS-independent (nitroglycerin) agonist. In addition, we measured superoxide anion levels in brain tissue under basal conditions in sedentary and exercised nondiabetic and diabetic rats. Furthermore, we used Western blot analysis to determine eNOS and nNOS protein levels in cerebral vessels/brain tissue in sedentary and exercised nondiabetic and diabetic rats. We found that ADP and NMDA produced a dilation of pial arterioles that was similar in sedentary and exercised nondiabetic rats. In contrast, ADP and NMDA produced only minimal vasodilation in sedentary diabetic rats. ExT restored impaired ADP- and NMDA-induced vasodilation observed in diabetic rats to that observed in nondiabetics. Nitroglycerin produced a dilation of pial arterioles that was similar in sedentary and exercised nondiabetic and diabetic rats. Superoxide levels in cortex tissue were similar in sedentary and exercised nondiabetic rats, were increased in sedentary diabetic rats, and were normalized by ExT in diabetic rats. Finally, we found that eNOS protein was increased in diabetic rats and further increased by ExT and that nNOS protein was not influenced by T1D but was increased by ExT. We conclude that ExT can alleviate impaired eNOS- and nNOS-dependent responses of pial arterioles during T1D.

Exercise training restores impaired dilator responses of cerebral arterioles during chronic exposure to nicotine

Our goal was to determine whether exercise training (ExT) alleviates impaired nitric oxide synthase (NOS)-dependent dilation of pial arterioles during chronic exposure to nicotine. We measured dilation of cerebral (pial) arterioles in sedentary and exercised control and nicotine-treated (2 mg·kg(-1)·day(-1) for 4 wk via an osmotic minipump) rats to an endothelial NOS (eNOS)-dependent (ADP), a neuronal NOS (nNOS)-dependent [N-methyl-D-aspartic acid (NMDA)], and a NOS-independent (nitroglycerin) agonist. In addition, we harvested brain tissue from sedentary and exercised control and nicotine-treated rats to measure the production of superoxide anion and measured superoxide dismutase-1 (SOD-1) protein in cerebral microvessels using Western blot. We found that eNOS-and nNOS-dependent, but not NOS-independent, vasodilation was impaired in nicotine-treated compared with control rats. In addition, the production of superoxide anion (lucigenin chemiluminescence) was increased, and SOD-1 protein decreased, in rats treated with nicotine compared with control rats. Further, although ExT did not significantly affect eNOS- or nNOS-dependent vasodilation in control rats, ExT restored impaired eNOS- and nNOS-dependent responses in nicotine-treated rats. In addition, the increase in superoxide anion production observed in nicotine-treated rats was reduced by ExT, and SOD-1 protein was increased in nicotine-treated rats by ExT. We suggest that ExT restores impaired NOS-dependent dilation of pial arterioles during chronic exposure to nicotine by a mechanism related to the formation of superoxide anion.

Influence of exercise on dilatation of the basilar artery during diabetes mellitus

Our goal was to examine whether exercise training alleviates impaired nitric oxide synthase (NOS)-dependent dilatation of the basilar artery in Type 1 diabetic rats. To test this hypothesis, we measured in vivo diameter of the basilar artery in sedentary and exercised nondiabetic and diabetic rats in response to NOS-dependent (acetylcholine) and -independent (nitroglycerin) agonists. To determine the potential role for nitric oxide in vasodilatation in sedentary and exercised nondiabetic and diabetic rats, we examined responses after NG-monomethyl-l-arginine (l-NMMA). We found that acetylcholine produced dilatation of the basilar artery that was similar in sedentary and exercised nondiabetic rats. Acetylcholine produced only minimal vasodilatation in sedentary diabetic rats. However, exercise alleviated impaired acetylcholine-induced vasodilatation in diabetic rats. Nitroglycerin produced dilatation of the basilar artery that was similar in sedentary and exercised nondiabetic and diabetic rats. l-NMMA produced similar inhibition of acetylcholine-induced dilatation of the basilar artery in sedentary and exercised nondiabetic and diabetic rats. Finally, we found that endothelial NOS (eNOS) protein in the basilar artery was higher in diabetic compared with nondiabetic rats and that exercise increased eNOS protein in the basilar artery of nondiabetic and diabetic rats. We conclude that 1) exercise can alleviate impaired NOS-dependent dilatation of the basilar artery during diabetes mellitus, 2) the synthesis and release of nitric oxide accounts for dilatation of the basilar artery to acetylcholine in sedentary and exercised nondiabetic and diabetic rats, and 3) exercise may exert its affect on cerebrovascular reactivity during diabetes by altering levels of eNOS protein in the basilar artery.

Impact of high-intensity exercise on nitric oxide exchange in healthy adults

PURPOSE

After exercise, exhaled NO concentration has been reported to decrease, remain unchanged, or increase. A more mechanistic understanding of NO exchange dynamics after exercise is needed to understand the relationship between exercise and NO exchange.

METHODS

We measured several flow-independent NO exchange parameters characteristic of airway and alveolar regions using a single breath maneuver and a two-compartment model (maximum flux of NO from the airways, J'(awNO), pL x s-1; diffusing capacity of NO in the airways, D(awNO), pL x s-1 x ppb-1; steady state alveolar concentration, C(alv,ss), ppb; mean airway tissue NO concentration, C(awNO), ppb), as well as serum IL-6 at baseline, 3, 30, and 120 min after a high-intensity exercise challenge in 10 healthy adults (21-37 yr old).

RESULTS

D(awNO) (mean +/- SD) increased (37.1 +/- 44.4%), whereas J'(awNO) and C(awNO) decreased (-7.27 +/- 11.1%, -26.1 +/- 24.6%, respectively) 3 min postexercise. IL-6 increased steadily after exercise to 481% +/- 562% above baseline 120 min postexercise.

CONCLUSION

High-intensity exercise acutely enhances the ability of NO to diffuse between the airway tissue and the gas phase, and exhaled NO might be used to probe both the metabolic and physical properties of the airways.

Inhibitory effects of voluntary wheel exercise on apoptosis in splenic lymphocyte subsets of C57BL/6 mice

Two-month-old mice were placed in cages with (Ex) or without exercise running wheels with free access to the wheel 24 h/day for 10 mo. An equal amount of food for both groups was provided daily. Ex mice ran an average of 33.67 km/wk initially, and exercise decreased gradually with age. Ex mice had gained an average of 43.5% less body weight at the end of the experiment. Although serum lipid peroxides were not altered by exercise, superoxide dismutase and glutathione peroxidase activities in serum were significantly increased. Flow cytometric analysis of spleen cells revealed an increased percentage of CD8+ T cells and a decreased percentage of CD19+ B cells in Ex mice (P < 0.05). Exercise decreased apoptosis in total splenocytes and CD4+ cells incubated with medium alone or with H(2)O(2), dexamethasone, tumor necrosis factor-alpha (TNF-alpha), or anti-CD3 monoclonal antibody (P < 0.05) and CD8+ cells with medium alone or with TNF-alpha (P < 0.05). Even though exercise did not alter the intracellular cytokines (TNF-alpha and interleukin-2) or Fas ligand, it did significantly lower interferon-gamma in CD4+ and CD8+ cells (P < 0.05). In summary, voluntary wheel exercise appears to decrease H(2)O(2)-induced apoptosis in immune cells as well as decrease interferon-gamma production.

Minerals, trace elements and related biological variables in athletes and during physical activity

This review concerns various minerals (sodium, potassium, calcium, magnesium, phosphorus), trace elements (zinc, manganese, selenium, copper, iron, cobalt, iodine, chromium, fluorine, lead, cadmium) and other biological variables (nitric oxide, L-carnitine, glutamine, serum transferrin receptor, biopyrrins) in relation to hemorheologic effects, stress, immune response and infections during physical and sports activities. In athletes, macroelements in the ionized form contribute to heart and muscle contractions, oxidative phosphorylation and the synthesis and activation of enzymatic systems. Zinc (Zn) protects against the effects of increased free reactive oxygen species such as copper (Cu) and manganese (Mn) (Cu-Zn superoxide dismutases; Mn superoxide dismutase). Selenium in glutathione peroxidase protects the cardiovascular system and the muscles, and helps combat allergic and inflammatory diseases. Copper and iron are involved in many aspects of energy metabolism and are important components in the synthesis of hemoglobin, myoglobin and cytochromes. Fluorine and Cu protect the ligaments and tendons. Physical activity appears to be beneficial to urban residents who are exposed to metal pollution (lead, cadmium). The data cited in this review are often contradictory and incomplete. It is still unclear in many cases how minerals are involved in physiological changes, and much work remains.

Epinephrine upregulates superoxide dismutase in human coronary artery endothelial cells

Regular exercise resulting in release of catecholamines is an oxidant stress, and yet it protects humans from acute cardiac events. We designed this study to examine the effect of epinephrine on free radical release and endogenous superoxide dismutase (SOD) gene and protein expression in human coronary artery endothelial cells (HCAECs). HCAECs were incubated with epinephrine (10(-9) to 10(-5) M) alone or with the water-soluble analog of vitamin E (trolox) (10(-5) M), the lipid-soluble vitamin E (5 x 10(-5) M), or the beta(1)-adrenergic blocker atenolol (10(-5) M). At 1 and 24 h of incubation with epinephrine, superoxide anion generation increased by 102 and 81% in the HCAECs. There was a marked increase in both MnSOD and Cu/ZnSOD mRNA and protein, as determined by RT-PCR and Western Analysis, respectively. Both MnSOD and Cu/ZnSOD activities were also increased. Pretreatment of HCAECs with trolox and vitamin E decreased superoxide anion generation (p <.05 vs. epinephrine alone) and blocked the subsequent upregulation of SOD mRNA and protein. Treatment of cells with the beta-blocker atenolol also blocked the upregulation of SOD (p <.05 vs. epinephrine alone). These observations suggest that epinephrine via beta(1)-adrenoceptor activation causes superoxide anion generation, and the superoxide subsequently upregulates the endogenous antioxidant species SOD. These observations may be the basis of long-term benefits of exercise.

Potential role of oxidized lipids and lipoproteins in antioxidant defense

The atherogenic oxidative modification of low-density lipoprotein is suggested to occur in the aortic intima. There is reasonable evidence to suggest that antioxidants might be beneficial in preventing or retarding the progression of atherosclerosis. Exercise, estrogens, and substitution of polyunsaturated fat for saturated fat are beneficial in the prevention of atherosclerosis. Yet, paradoxically, they are capable of inducing an oxidative stress. To reconcile with this paradox, we postulate that under certain conditions an oxidative stress might be beneficial by inducing antioxidant enzymes in arterial cells. However, those with genetic deficiency in antioxidant enzymes or those who poorly respond to oxidative stress or those with overwhelming plasma oxidative stress might need additional antioxidant protection.

Antioxidants: what role do they play in physical activity and health?

Exercise appears to increase reactive oxygen species, which can result in damage to cells. Exercise results in increased amounts of malondialdehyde in blood and pentane in breath; both serve as indirect indicators of lipid peroxidation. However, not all studies report increases; these equivocal results may be due to the large intersubject variability in response or the nonspecificity of the assays. Some studies have reported that supplementation with vitamins C and E, other antioxidants, or antioxidant mixtures can reduce symptoms or indicators of oxidative stress as a result of exercise. However, these supplements appear to have no beneficial effect on performance. Exercise training seems to reduce the oxidative stress of exercise, such that trained athletes show less evidence of lipid peroxidation for a given bout of exercise and an enhanced defense system in relation to untrained subjects. Whether the body's natural antioxidant defense system is sufficient to counteract the increase in reactive oxygen species with exercise or whether additional exogenous supplements are needed is not known, although trained athletes who received antioxidant supplements show evidence of reduced oxidative stress. Until research fully substantiates that the long-term use of antioxidants is safe and effective, the prudent recommendation for physically active individuals is to ingest a diet rich in antioxidants.

Oxidative stress, acute and regular exercise: are they really harmful in the diabetic patient?

Oxidative stress has been involved in the pathogenic process of a variety of diseases including diabetes mellitus. The production of oxidative reactive products has been involved in biochemical changes in bio-molecules that might produce tissue damage directly related to some of the main vascular complications in the diabetic patient. On the other hand, exercise, paradoxically, is a well-recognized model of oxidative stress and also an important therapeutic tool in diabetes management. Therefore, the relationship between oxidative stress and exercise in diabetic patients implies an interesting biochemical paradox due to some of the negative effects of exercise principally by the increase of oxidative species in plasma. The effect of oxidative stress during an acute exercise and after an aerobic training period on those patients remains unknown and needs to be studied.

Superoxide Anion Generation, Superoxide Dismutase Activity, and Nitric Oxide Release in Human Internal Mammary Artery and Saphenous Vein Segments

BACKGROUND: Internal mammary artery (IMA) as conduit for a coronary artery bypass graft (CABG) stays patent longer and more often than saphenous vein (SV). However, the precise differences in the biology of IMA and SV are unclear. METHODS AND RESULTS: To examine inherent difference in superoxide anion, superoxide dismutase (SOD) and nitric oxide (NO) formation in IMA and SV as a basis for differences in patency rates, we measured these parameters in vascular segments of patients undergoing CABG. Superoxide anion generation was measured by lucigenin chemiluminescence and reduction of cytochrome c, SOD by inhibition of pyrogallol auto-oxidation, and No as nitrite/nitrate fluorometrically using 2-3-diaminonaphthalene as a probe. Generation of superoxide anion, SOD activity, and No formation were all greater in the IMA than in the SV segments (IMA:SV = 2.6:1, 2.9:1, 1, and 3.0:1, respectively, all P <.010. There was a positive correlation between superoxide anion generation and SOD activity (r = 0.65, P <.05; r = 0.70, P <.05 in IMA and SV, respectively) and NO release (r = 0.68, P <.05; r = 0.75, P <.03 in IMA and SV, respectively). Western blot analysis showed no differences in SOD and NO synthase protein expression in IMA and SV segment homogenates. To examine whether greater superoxide anion generation, SOD activity, and NO formation are unique to IMA, we studied pulmonary artery (PA) and pulmonary vein (PV) segments taken from patients undergoing lung resection. Superoxide anion generation, SOD activity, and NO formation were also found to be greater in PA than in PV segments. CONCLUSIONS: Inherently greater superoxide anion generation and subsequently increased formation of SOD and NO release in IMA (vs SV) may be a factor in the greater patency of the former as CABG conduit. Because both IMA and PA are exposed to pulsatile stretch and cary blood at higher pressure than the SV and PV, it is likely that these 2 factorsd account for the observed differences.

Impact of treadmill exercise on early apoptotic cells in mouse thymus and spleen

Lymphocyte apoptosis occurs in response to stressors such as thermal injury, trauma, sepsis, and surgery. This study evaluated the effect of a single bout of physical exercise stress on the induction of apoptosis in murine thymocytes and splenic lymphocytes. Female C57BL/6 mice, treadmill exercised at a submaximal intensity (35 m/min, 6% grade) for 90 min or serving as controls (walking on treadmill at 12 m/min, 6% grade, 5 min), were sacrificed 5 min or 120 min after completion of exercise. The percent of apoptotic, necrotic, and viable thymocytes and splenocytes were determined by flow cytometry using annexin V FITC and propidium iodide. There was a significantly higher percent of viable splenocytes in the mice sampled 120 min after cessation of exercise than treadmill control animals (p<0.05). In the thymus, there was a significantly lower percent of apoptotic (p<0.5) and a significantly higher percent of viable (p<0.05) cells in exercised mice sampled at 120 min after exercise relative to controls. Absolute numbers of thymocytes and splenocytes did not differ by exercise treatment condition. Plasma corticosterone levels were elevated immediately after exercise and were negatively correlated with the percent of viable lymphocytes in the spleen. During the time frame sampled, submaximal exercise is associated with a lower % of thymocytes expressing early markers of apoptosis, despite elevated plasma corticosterone levels. Retention of self-reactive, viable thymocytes which would normally be deleted or selective trafficking of apoptotic thymocytes out of the thymus may be involved in the exercise effect. Additional studies are necessary to identify the mechanisms for this shift in proportions of apoptotic and viable cells in lymphoid compartments with exercise.