Prooxidant-antioxidant equilibrium in rowers: effect of a single dose of vitamin E

AIM: The purpose of this research was to explain whether a single dose of vitamin E influences on disturbances of pro-oxidant-antioxidant equilibrium induced a laboratory 2,000 m rowing test. METHODS: The athletes were divided into two groups: vitamin E (1.000 mg alfa-tocopherol acetate) and P (placebo: cod-liver oil) supplemented 3 h before exercise. In the subjects' blood levels of following parameters were estimated: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), lipid peroxidation products (TBARS) and protein carbonyls (PC). Creatine kinase (CK) and beta-glucuronidase (betaG) activities were also measured as markers of muscle damage. RESULTS: The applied exercise at maximal intensity (lactate: vitamin E=14.39+/-1.77 mmol/L, P=14.09+/-1.4 mmol/L) caused significant changes in the tested parameters in both groups: SOD (vitamin E ?30%, P ?50%), CAT (vitamin 70%, P 12%), GPx (vitamin 49%, P 45%), TBARS (vitamin 70%, P 71%), PC (vitamin 41%, P 78%), CK (vitamin 19%, P 32%), betaG (vitamin 42%, P 47%). The P/A ratio (TBARS/SOD+CAT+GPx) was significantly lower in vitamin E in comparison with placebo, but after 30 min and 24 h restitution it returned to pre-exercise level. Between P/A ratio and PC concentration there was observed positive correlation (P<0.001). No effect of vitamin E on CK and betaG activities were observed. CONCLUSIONS: A single dose of 1,000 mg vitamin E enhances oxidative defense thus attenuates oxidative damage but it is not so much relevant to recommend the antioxidant supplementation by rowers.     

Biochemical assessments of total antioxidant status in active and nonactive female adults with intellectual disability

Long-term physical activity is known to increase the antioxidant defense (AOD) system, whereas sedentary lifestyle is associated with oxidative stress (OS). The underlying molecular mechanisms are incompletely understood. The aim of this prospective, nonrandomized study was to evaluate and compare the relationship between long-term physical activity and inactivity and plasma antioxidant status in female adults with intellectual disability (ID) that were diagnosed after birth. A total of 21 adults with ID were examined. The following AOD was examined: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), vitamin E, and vitamin A. Inactive persons with ID had significantly lower SOD (p<0.05), CAT (p<0.05), and GPX (p<0.05). All plasma vitamin levels were significantly higher in physically active subjects (vitamin A: 1.42 +/- 0.05 mmol/l, vitamin E: 31.32 +/- 2.62 mmol/l) than in sedentary control subjects (vitamin A: 1.02 +/- 0.03 mmol/l, vitamin E: 18.88 +/- 2.23 mmol/l) p<0.01. These results suggest that regular physical activity is associated with preserved AODs in adults with ID. As opposed to a physically active lifestyle, an inactive results in low levels of antioxidants.     

Oxidative stress levels in rats following exposure to oxygen at 3 atm for 0-120 min

BACKGROUND: Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. We previously defined the pressure-related oxidative effects of HBO in several tissues of rats. This study was performed to elucidate the relationship of HBO exposure time to its oxidative effects. METHODS: A total of 49 rats were randomly divided into 5 groups. Study groups were subjected to 3 atm HBO for 30, 60, 90, and 120 min except the control group. Their blood and lungs were removed immediately after exposure and used for analysis. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels were determined to reflect oxidant and antioxidant status. RESULTS: TBARS levels were found to increase in a time-dependent manner in both erythrocytes [median (min-max); from 0.65 (0.39-0.84) with 30 min HBO exposure up to 1.26 (1.00-1.44) nmol x g(-1) hemoglobin after 120 min] and lung tissue [from 2140 (1550-2510) up to 5465 (5090-5950) nmol x g(-1) protein]. Similarly, SOD activity also presented a dose-dependent course from 0.06 (0.05-0.10) to 0.18 (0.14-0.26) U x g(-1) hemoglobin in erythrocytes and from 16,660 (3479-25,994) to 52,522.5 (41,362-65,799) U x g(-1) protein in lung tissue. In contrast, GSH-Px activity reflected an irregular trend; its levels were mostly found to be increased, but they were decreased at one stage (in the erythrocytes of 30-min exposed rats). CONCLUSIONS: The results of this study exhibited a clear relationship of HBO-induced oxidative action to exposure time. This action was most pronounced from 90 to 120 min of exposure.     

活血生肌类中药对大鼠急性骨骼肌钝挫伤后氧化应激的影响

目的:观察活血生肌类中药对大鼠骨骼肌钝挫伤后组织修复过程中氧化应激的影响。方法:72只雄性SD大鼠随机分为中药治疗组、生理盐水组、自然愈合组,每组24只。采用打击装置造成大鼠右侧腓肠肌中段钝挫伤模型,分别于各组损伤局部注射黄芪丹参注射液、生理盐水和不作处理。另6只作为空白对照(未经任何处理)。于损伤后1、4、7和14天取大鼠腓肠肌测定丙二醛(MDA)含量和过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-px)活性。结果:与生理盐水组和自然愈合组相比,中药治疗组腓肠肌SOD、GSH-px活性在伤后第4、7天显著升高(P<0.05),而CAT活性无明显变化(P>0.05)。中药治疗组腓肠肌MDA含量在伤后第4、7天显著低于生理盐水组和自然愈合组(P<0.05)。结论:活血生肌类中药可明显减轻骨骼肌钝挫伤愈合过程中的氧化性损伤,并显著提高骨骼肌SOD和GSH-px的活性。     

The prophylactic effect of vitamin C on oxidative stress indexes in rat eyes following exposure to radiofrequency wave generated by a BTS antenna model

Abstract

Purpose: This study was conducted to evaluate the effect of radiofrequency wave (RFW)-induced oxidative stress in the eye and the prophylactic effect of vitamin C on this organ by measuring the antioxidant enzymes activity including: glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT), and malondialdehyde (MDA).

Materials and methods: Thirty-two adult male Sprague-Dawley rats were randomly divided into four experimental groups and treated daily for 45 days as follows: Control, vitamin C (L-ascorbic acid 200 mg/kg of body weight/day by gavage), test (exposed to 900 MHz RFW) and the treated group (received vitamin C in addition to exposure to RFW). At the end of the experiment all animals were sacrificed, their eyes were removed and were used for measurement of antioxidant enzymes and MDA activity.

Results: The results indicate that exposure to RFW in the test group decreased antioxidant enzymes activity and increased MDA compared with the control groups (P < 0.05). In the treated group vitamin C improved antioxidant enzymes activity and reduced MDA compared to the test group (P < 0.05).

Conclusions: It can be concluded that RFW causes oxidative stress in the eyes and vitamin C improves the antioxidant enzymes activity and decreases MDA.     

Oxidative stress in half and full Ironman triathletes

INTRODUCTION: Ultraendurance athletes who maintain a very high volume of exercise may, as a result of greater production of reactive oxygen species (ROS), be particularly susceptible to oxidative damage. PURPOSE: This study sought to examine and compare pre- and postrace markers of oxidative stress in ultraendurance athletes training for, and competing in, either a half or a full Ironman triathlon. METHODS: Resting and postexercise blood was sampled from 16 half Ironman triathletes, 29 full Ironman triathletes, and age-matched, relatively inactive controls. Blood was analyzed for markers of oxidative stress (malondialdehyde (MDA) concentration) and antioxidant status (glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities). RESULTS: Compared with controls, the half Ironman triathletes had significantly (P < 0.001) higher erythrocyte GPX activity at rest, whereas the Ironman triathletes had significantly (P < 0.05) lower resting plasma MDA and significantly (P < 0.05) greater resting activities of GPX and CAT compared with controls. As a result of the half Ironman triathlon, there was a significant (P < 0.05) increase in MDA and significant (P < 0.05) decreases in erythrocyte GPX, SOD, and CAT activities. These changes also occurred in response to the Ironman triathlon; MDA significantly (P < 0.05) increased, and there were significant (P < 0.001) decreases in GPX, CAT, and SOD activities. Users of antioxidant supplements in both the half and full Ironman races had significantly (P < 0.05) elevated MDA after races compared with nonsupplementers. CONCLUSION: The present investigation indicates that training for and competing in half and full Ironman triathlons has different effects on erythrocyte antioxidant enzyme activities and oxidative stress.     

Exercise-induced oxidative stress in G6PD-deficient individuals

PURPOSE: This study was designed to investigate whether individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency can exercise without greater perturbations in their redox status compared with non-G6PD-deficient individuals. METHODS: Nine males with established G6PD deficiency and nine males with normal G6PD activity performed two exhaustive treadmill exercise protocols of different duration (the shorter one lasting 12 min and the longer one 50 min). Several hematological parameters, reduced glutathione (GSH), oxidized glutathione (GSSG), thiobarbituric acid reactive substances (TBARS), protein carbonyls, catalase, and total antioxidant capacity (TAC) were measured in the blood before and after each exercise bout. RESULTS: Both GSH and GSSG were significantly higher in the control group compared with the G6PD-deficient group at baseline (0.404 +/- 0.101 vs 0.195 +/- 0.049 mmol.L(-1) for GSH and 0.047 +/- 0.012 vs 0.012 +/- 0.006 mmol.L(-1) for GSSG; P < 0.05); as a result, their ratio was not significantly different between the two groups (P > 0.05). All other oxidative stress indices were not different between groups at rest (P > 0.05). Exercise of both durations affected significantly (P < 0.05) and similarly the levels of all oxidative stress indices either in the G6PD-deficient group or in the control group. Only the long exercise affected GSH status significantly (P < 0.05), whereas both short and long exercise increased the levels of TBARS, protein carbonyls, catalase activity, and TAC to a similar extent (P < 0.05). CONCLUSION: G6PD-deficient individuals are able to exercise until exhaustion without higher oxidative stress compared with non-G6PD-deficient individuals. Exercise duration is an important determinant of the magnitude of exercise-induced changes for GSH, GSSG, and GSH/GSSG, but not for TBARS, protein carbonyls, catalase activity, or TAC.     

Plasma glutathione peroxidase activity as a potential indicator of hypoxic stress in breath-hold diving

INTRODUCTION: Diving mammals can cope with oxidants which are produced in excess during the reoxygenation of hypoxic tissues. This study addresses the question of whether antioxidants can adapt and whether it allows humans to tolerate the hypoxic stress induced by a single breath-holding in the course of a dynamic diving exercise and protect them from oxidative insult. METHODS: There were 20 male subjects who performed submaximal apnea dynamic diving (ADD). Nine control subjects stayed out of the water and breathed normally. Venous blood samples were collected 1 h before and immediatly after ADD. RESULTS: ADD induced a significant increase in plasma glutathione peroxidase (GPx-3) activity (from 397.5 +/- 44.4 to 410 +/- 43 U x L(-1)), blood reduced glutathione (GSH) (from 1060 +/- 302 to 1292 +/- 213 micromol x L(-1)), and in plasma creatine kinase activity (from 215 +/- 137 to 235 +/- 152 U x L(-1)). The activity of the erythrocyte superoxide dismutase and glutathione peroxidase, as well as the blood oxidized glutathione and the plasma thiobarbituric acid reactive substances concentrations, were maintained at their basal level. The level of training, characterized by the duration and distance of the dive, had no effect on the markers used. CONCLUSION: GPx-3 and GSH could constitute the most readily mobilizable antioxidants that would then contribute to the buffering against a sudden increase in the generation of radical oxygen species. These biomarkers could be used as tools for establishing oxidative stress during hypoxia. The response of GPx-3 to hypoxia could be of physiological relevance.     

Effets d’un exercice de type anaérobie sur le statut antioxydant enzymatique au cours de la récupération chez les judokas

Aim

To evaluate the effect of the anaerobic exercise on the enzymatic antioxidant statute in judokas’ regional level, because the effects of anaerobic exercise on the free radicals and antioxidants are relatively rare and have some divergences.

Materials and methods

We made this study on ten male judokas (age = 18.1 ± 1.6 years; weight = 77.2 ± 11.6 kg; height = 176.4 ± 4.6 cm), which carried out 30 seconds anaerobic capacity test (Wingate test). Blood samples were taken, by an intravenous catheter, at rest (R), immediately after the Wingate test (P0) then five minutes later (P5), 10 minutes later (P10) then 20 minutes later (P20). The measured parameters are: the superoxide dismutase (SOD), the glutathion peroxidase (GPx) and the total antioxidant statute (SAT).

Results

The concentration of the SOD increases significantly (p < 0.05) at (P0); and regains the baseline values at (P20). The concentration of GPx increases significantly (p < 0.05) in (P0); in (P10) GPx reaches the baseline values. No significant effect of the anaerobic exercise was observed on the concentration of the SAT. Positive correlation was observed between the SOD and GPx to p < 0.05.

Conclusion

The anaerobic exercise modifies the activity of the antioxidant enzymes with different kinetics.     

Exercise does not induce oxidative stress in trained heart transplant recipients

PURPOSE: The objectives of this study were twofold: 1) to determine the effect of incremental exercise to volitional fatigue on plasma levels of lipid peroxidation (malondialdehyde) in heart transplant recipients (HRT) and 2) to examine blood antioxidant capacity in HTR by assessment of antioxidant enzyme activities and vitamin E levels. METHODS: Seven endurance-trained HTR (mean +/- SD; age 39.7 +/- 12.8 yr) and seven endurance-trained healthy, age-matched control subjects (HC) (mean age 40.6 +/- 10.7 yr) performed a symptom-limited incremental exercise test on a cycle ergometer. Venous blood samples were obtained at rest, exercise, and during recovery and analyzed for plasma levels of malondialdehyde (MDA) as well as markers of blood antioxidant capacity. After exercise and during recovery, all dependent measures were corrected for plasma volume changes induced by exercise. Significance was established at (P < 0.05). RESULTS: No group differences existed in plasma levels of MDA at rest. Further, graded exercise did not alter plasma levels of MDA in either group. Resting erythrocyte glutathione peroxidase (GPX) activity was significantly lower and erythrocyte superoxide dismutase (SOD) activity was higher in HTR compared with HC. Finally, at rest, no group differences existed in plasma GPX activity or vitamin E levels. CONCLUSIONS: Graded exercise to fatigue does not promote an increase in oxidative stress in blood of exercise trained HTR. Therefore, physical exercise does not appear to pose an oxidative-stress risk for these patients.     

Determination of circulating hemoglobin mass and related quantities by using capillary blood

PURPOSE: A standardized carbon monoxide (CO) rebreathing procedure with measurements of CO-hemoglobin, hemoglobin concentration ([Hb]), and hematocrit (Hct) enables to determine total Hb mass (Hb(tot)), blood, erythrocyte, and plasma volume (BV, EV, and PV). These calculations are normally based on venous blood samples. However, micromethods also allow determinations from capillary blood. METHODS: The accuracy of using capillary blood for Hb(tot), BV, EV, and PV determination was evaluated in 42 men (age: 25.1 +/- 4.0 yr, body mass: 80.3 +/- 9.6 kg) by comparison of capillary and venous data. RESULTS: Capillary Hb(tot) (962 +/- 110 g) did not differ from venous values (959 +/- 106 g). Hb(tot) values were highly correlated (r = 0.987, P < 0.001, SEE 18 g). Also, capillary and venous BV, PV, and EV were highly correlated (0.94 < r < 0.98), but slightly different (-2.7 to 0.9%) because of higher capillary than venous [Hb] and Hct. Coefficients of variation of repeated Hb(tot), EV, PV, and BV measurements (3.0-5.2%) were similar in capillary and venous blood. CONCLUSION: Calculation of Hb(tot) using capillary blood is as accurate and reliable as using venous blood.     

Lipid peroxidation in judoists using oral contraceptives

12 female judoists using oral contraceptives (OCU) containing 0.03?mg ethinylestradiol and 3?mg drospirenone for 20±12 months (mean±SD) were compared with a control group of 14 judoist noncontraceptive users (NCU) in order to evaluate resting (T1) and postexercise (T2) lipid peroxidation (LPO) and antioxidant parameters. Data were collected 20?min before and 10?min after a morning session of judo training and included determination of lag phase (Lp) before free radical-induced oxidation, glutathione peroxidase (GPx), α-tocopherol, retinol, and oxidative stress markers related to LPO. Significantly higher resting oxidative stress (+125.8 and +165.2% for malondialdehyde and lipid peroxides, respectively) and lower values of Lp and GPx (?-?23.4 and -?12.1%, respectively) were observed in the OCU compared with NCU. The judo training session induced an increase in plasma LPO whatever the treatment. We noted significant increases in Lp (+14.7%; p<0.05 vs. preexercise) and GPx (22.1%; p<0.05 vs. preexercise) only in the NCU group. We suggest that a judo training session favourably altered some antioxidants in NCU but not in OCU. As excessive oxidative stress is linked to the development of several chronic diseases, the use of agents to reduce antioxidants may be reasonable in OCU.     

Effects of blood transfusions on some hematological variables in endurance athletes

Selected hematological variables (blood hemoglobin concentration [Hb], serum (s-) iron, s-bilirubin, s-ferritin, blood lactate, and s-erythropoietin [Epo]) were analyzed before and for 4 wk after autologous blood transfusions. A group of well-trained (8 male and 4 female) former endurance athletes was phlebotomized and 3-4 months later reinfused with the freezer-stored autologous red blood cells (RBC) from 1350 ml of blood. The [Hb] increased significantly (P less than 0.001 for both sexes) from 146.7 +/- 5.31 and 131.7 +/- 11.20 g. l-1 immediately before reinfusion to maximum values of 163.5 +/- 7.47 and 155.9 +/- 11.43 g.l-1 (mean +/- SD) in males and females, respectively, 2 d after reinfusion. S-iron increased transiently 5 h after reinfusion. S-bilirubin remained unchanged throughout the study. S-ferritin increased gradually (P less than 0.02) from 48 +/- 32.91 mmol.l-1 before reinfusion to a maximum of 80.8 +/- 39.52 mmol.l-1 2 wk after reinfusion. S-[Epo] increased transiently (P less than 0.01) from 8.83 +/- 2.51 (mean +/- SD) to 12.36 +/- 5.64 U.l-1, (mean +/- SD) 5 h after reinfusion. Subsequently, there was a significant marked decrease in s-[Epo] to 5.85 +/- 1.32 U.l-1, (mean +/- SD) 1 d after reinfusion (P less than 000.1, as compared to before reinfusion). Thereafter, s-[Epo] remained low throughout the study. Blood lactate was significantly decreased only the first 2 d after reinfusion (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of [11C]acetate and [15O]O2 PET for the assessment of myocardial oxygen utilization in patients with chronic myocardial infarction

Carbon-11 acetate positron emission tomography (PET) has been widely used to assess regional oxidative metabolism of the heart. However, the accuracy of [11C]acetate PET in assessing oxidative metabolism in infarcted myocardium remains controversial. Thirteen patients with stable coronary artery disease and old myocardial infarction were studied. The 15O-based PET studies yielded regional blood flow (rMBF, ml/min/g) and oxygen consumption (rMMRO2, ml/min/g), which was compared with the myocardial clearance rate constant (kmono) of [11C]acetate in segments with rMBF > or = 75% (group A), 50%-74% (group B) or < 50% (group C) of the normal reference segment. Mean MBF was 0.96 +/- 0.08 ml/g/min in group A, 0.67 +/- 0.06 ml/g/min in group B and 0.42 +/- 0.07 ml/g/min in group C segments. The segmental rMMRO2 correlated linearly with kmono (r = 0.89, P < 0.001, y = 0.61x + 0.026). The kmono/rMMRO2 ratio was comparable in the group A and B segments (0.99 +/- 0.19 vs 1.07 +/- 0.21, P = NS). However, the ratio was significantly higher in the group C segments (1.28 +/- 0.35, P = 0.037). It is concluded that kmono of [11C]acetate correlates linearly with rMMRO2 determined by [15O]O2 inhalation. However, kmono appears to yield higher rMMRO2 estimates than the [15O]O2 method in low-flow areas.     

Arterial oxygen saturation and diving response during dynamic apneas in breath-hold divers

Competitive breath-hold divers try to achieve maximum times, depths, or distances underwater, thereby risking hypoxic syncope. In the present study, the cardiorespiratory responses to dynamic apnea (simultaneously initiated apneas and dynamic leg exercise) were investigated in 10 breath-hold divers. The divers performed 60 s dynamic apneas with the face in air (A) or face immersed in cold water (AFI). During apneas, the arterial oxygen saturation was reduced (A: −10%), but to a lesser extent during AFI (−6%, P <0.01), reaching a nadir 10–15 s post-apnea. Also, changes in end-tidal O₂ and CO₂ pressures ( P _etO₂/ P _etCO₂) were smaller during AFI than A (Δ P _etO₂: 8.2 vs 8.7 kPa, P <0.01; Δ P _etCO₂: 3.1 vs 3.2 kPa, P <0.05). The heart rate was lower during AFI than A (66 vs 78 bpm, P <0.01), reflecting an augmented diving response during AFI. The maximum safe breath-hold time under the conditions of the present study was calculated to be 101 and 106 s for A and AFI, respectively, consistent with the dynamic apnea times achieved by world-class apnea divers. It is concluded that the augmented diving response during face immersion apneas is associated with a slower reduction of the pulmonary (and arterial) oxygen store, probably delaying the occurrence of a hypoxic syncope.     

终末期肾病氧化应激状态的研究

为了解氧化应激状态及肾替代治疗对终末期肾病(ESRD)患者的影响 ,笔者比较了正常人、慢性肾功能不全 (CRF)、腹膜透析(CAPD)和血液透析 (HD)病人之间血浆还原型谷胱甘肽 (GSH)、维生素E、丙二醛 (MDA)和蛋白羰基含量及全血谷胱甘肽过氧化物酶(GPx)活性的差异。结果显示与正常人相比 ,CRF病人循环GSH浓度和GPx活性降低 (P均 <0 0 5 ) ,CAPD和HD病人循环GSH、维生素E浓度和GPx活性均明显降低 (P均 <0 0 5 ) ,而血浆MDA和蛋白羰基含量均显著升高 (P均 <0 0 5 ) ;HD患者血浆GSH和维生素E含量比CRF组降低(P均 <0 0 5 )。提示ESRD患者处于氧化应激状态 ,血液透析进一步加剧这种病理生理改变     

Reduction of Hb levels during the racing season in nonsideropenic professional cyclists

Hematological variables of 40 professional cyclists, all receiving intravenous iron supplementation, were followed during a 15-month period. Mean values for red blood cells (RBC), hemoglobin (Hb), and hematocrit (Ht) were significantly lower during the racing season (RS) than during the nonracing periods (NRP) (RBC: RS = 4.53 +/- 0.34 millions/mm3, NRP = 5.09 +/- 0.36 millions/mm3; line 7 of abstract: Hb: RS = 14.2 +/- 0.9 g/dl, MRS = 15.2 +/- 0.9 g/dl; Ht: RS = 40.7 +/- 2.7% NRP = 44.4 +/- 2.9%; P less than 0.001 for all). However, mean values for ferritin and mean corpuscular hemoglobin (MCH) were significantly higher during the racing season (ferritin: RS = 422 +/- 398 ng/ml, NRP = 311 +/- 321 ng/ml, P less than 0.05; MCH: RS = 31.5 +/- 1.3 pg, NRP = 30.0 +/- 1.4 pg; P less than 0.001). These results suggest that the reductions in RBC, Hb, and Ht found in professional cyclists during the racing season are not the consequence of a diminution of iron stores but rather of reduced erythropoiesis and increased RBC destruction.     

Static apnea effect on heart rate and its variability in elite breath-hold divers

BACKGROUND: The diving response includes cardiovascular adjustments known to decrease oxygen uptake and thus prolong apnea duration. As this diving response is in part characterized by a pronounced decrease in heart rate (HR), it is thought to be vagally mediated. METHODS: In five professional breath-hold divers (BHDs) and five less-trained controls (CTL), we investigated whether the diving response is in fact associated with an increase in the root mean square successive difference of the R-R intervals (RMSSD), a time-domain heart rate variability (HRV) index. HR behavior and arterial oxygen saturation (SaO2) were continuously recorded during one maximal apnea. Short-term changes in SaO2, HR, and RMSSD were calculated over the complete apnea duration. RESULTS: BHDs presented bi-phasic HR kinetics, with two HR decreases (32 +/- 17% and 20 +/- 10% of initial HR). The second HR decrease, which was concomitant to the pronounced SaO2 decrease, was also simultaneous to a marked increase in RMSSD. CTL showed only one HR decrease (50 +/- 10% of initial HR), which appeared before the concomitant SaO2 and RMSSD changes. When all subject data were combined, arterial desaturation was positively correlated with total apnea time (r = 0.87, P < 0.01). CONCLUSION: This study indicates that baroreflex stimulation and hypoxia may be involved in the bi-phasic HR response of BHDs and thus in their longer apnea duration.     

Reduced oxidative metabolic response in dysfunctional myocardium with preserved glucose metabolism but with impaired contractile reserve.

The recovery of function in myocardium defined as viable by (18)F-FDG PET may differ from that defined by dobutamine stress echocardiography (DSE). The aim of this study was to investigate the difference in the oxidative metabolic response between myocardial segments with preserved contractile reserve (CR) and those without CR, in segments with and without preserved glucose metabolism (GM), using (11)C-acetate PET. METHODS: Twenty patients with previous myocardial infarction (left ventricular ejection fraction, 37.1% +/- 16.5%) underwent dynamic (11)C-acetate PET at rest and during dobutamine (7.5 microg/kg/min) infusion. GM was evaluated using (18)F-FDG PET and CR was evaluated using DSE. Dysfunctional segments were divided into 3 groups: group A (n = 26) with preserved CR and GM, group B (n = 15) without CR but with preserved GM, and group C (n = 41) without CR and without preserved GM. RESULTS: Resting oxidative metabolism (k mono = monoexponential clearance rate) was preserved in group A and group B (0.052 +/- 0.011/min vs. 0.051 +/- 0.012/min, P = not significant) but was reduced in group C (0.040 +/- 0.015/min) (P < 0.03 vs. group A and group B). The change in k mono, as a measure of the metabolic response to low-dose dobutamine, was significantly higher in group A (0.018 +/- 0.012) than that in group B (0.0075 +/- 0.0096, P < 0.03) and group C (0.0080 +/- 0.012, P < 0.005). CONCLUSION: Viable segments based on (18)F-FDG PET have preserved resting oxidative metabolism. However, segments without CR but with preserved GM show a reduction in the oxidative metabolic response to low-dose dobutamine infusion. The decrease in CR may be related to the reduction in the metabolic response to inotropic stimulation despite preservation of tissue viability on (18)F-FDG PET.     

Effect of aerobic and anaerobic metabolism on free radical generation swimmers

PURPOSE: In this study, changes in antioxidant systems due to free radicals were investigated in short distance (100-m) and long-distance (800-m) swimmers, within whom the anaerobic and aerobic metabolisms dominate, respectively. METHODS: For this study, swimmers aged between 15 and -21 yr swam 800 m (N = 10) and 100 m (N = 9). Venous blood samples were taken before swimming, and at 1-, 20-, and 40-min intervals after swimming. Lactate, catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) levels were determined in the blood samples. RESULTS: The increase of lactate levels was statistically significant in the swimmers, both after the 100- and 800-m distances as compared with the preswimming levels (P < 0.001, P < 0.001). Catalase activity was increased in the first minute postswimming as compared with preswimming levels. Catalase activity then decreased at the 20- and 40-min intervals as compared with the 1-min postswimming interval, at both 100- and 800-m distances (P < 0.01, P < 0.001). GPx activity was also increased in the first minute after swimming as compared with preswimming levels. GPx activity then decreased at the 20- and 40-min intervals when compared with the 1-min postswimming level. This occurred in both 100- and 800-m swimmers (P < 0.001, P < 0.001). GSH activity was decreased in the first minute after swimming, compared with the preswimming levels. GSH activity then increased at the 20- and 40-min postswimming intervals, as compared with the first-minute level. Again, this occurred in both the 100- and 800-m swimmers (P < 0.001, P < 0.01). CONCLUSION: We concluded that both long-distance and particularly short-distance (100-m) swimming increased the activities of antioxidant defense enzymes.