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This paper reports a real-time study of the codynamical changes in the release of endogenous nitric oxide (NO) and oxygen ([O.sub.2]) consumption in a rot neocortex in vivo upon electrical stimulation using an amperometric NO/[O.sub.2] dual microsensor. Electrical stimulation induced transient cerebral hypoxia due to the increased metabolic demands that were not met by the blood volume inside the stimulated cortical region. A NO/ [O.sub.2] dual microsensor was successfully used to monitor the pair of real-time dynamic changes in the tissue NO and [O.sub.2] contents. At the onset of electrical stimulation, there was an immediate decrease in the cortical tissue [O.sub.2] followed by a subsequent increase in the cortical tissue NO content. The averages of the maximum normalized concentration changes induced by the stimulation were a 0.41 ([+ or -] 0.04)-fold decrease in the [O.sub.2] and a 3.6 ([+ or -] 0.9)-fold increase in the NO concentrations when compared with the corresponding normalized basal levels. The peak increase in NO was always preceded by the peak decrease in [O.sub.2] in all animals (n = 11). The delay between the maximum decrease in [O.sub.2] and the maximum increase in NO varied from 3.1 to 54.8 s. This rather wide variation in the temporal associations was presumably attributed to the sparse distribution of NOS-containing neurons and the individual animal's differences in brain vasculatures, which suggests that a sensor with fine spatial resolution is needed to measure the location-specific real-time NO and [O.sub.2] contents. In summary, the developed NO/[O.sub.2] dual mierosensor is effective for measuring the NO and [O.sub.2] contents in vivo. This study provides direct support for the dynamic role of NO in regulating the cerebral hemodynamics, particularly related to the tissue oxygenation. 10.1021/ac1013496

High-resistance interval training produces substantial gains in sprint and endurance performance of cyclists in the competitive phase of a season. Here, we report the effect of changing the cadence of the intervals. We randomized 18 road cyclists to 2 groups for 4 weeks of training. Both groups replaced part of their usual training with 8 30-minute sessions consisting of sets of explosive single-leg jumps alternating with sets of high-intensity cycling sprints performed at either low cadence (60-70 [min.sup.-1]) or high cadence (110-120 [min.sup.-1]) on a training ergometer. Testosterone concentration was assayed in saliva samples collected before and after each session. Cycle ergometry before and after the intervention provided measures of performance (mean power in a 60-s time trial, incremental peak power, 4-mM lactate power) and physiologic indices of endurance performance (maximum oxygen uptake, exercise economy, fractional utilization of maximum oxygen uptake). Testosterone concentration in each session increased by 97% [+ or -] 39% (mean [+ or -] between-subject SD) in the low-cadence group but by only 62% [+ or -] 23% in the high-cadence group. Performance in the low-cadence group improved more than in the high-cadence group, with mean differences of 2.5% (90% confidence limits, [+ or -]4.8%) for 60-second mean power, 3.6% ([+ or -]3.7%) for peak power, and 7.0% ([+ or -]5.9%) for 4-mM lactate power. Maximum oxygen uptake showed a corresponding mean difference of 3.2% ([+ or -]4.2%), but differences for other physiologic indices were unclear. Correlations between changes in performance and physiology were also unclear. Low-cadence interval training is probably more effective than high-cadence training in improving performance of well-trained competitive cyclists. The effects on performance may be related to training-associated effects on testosterone and to effects on maximum oxygen uptake. KEY WORDS athlete, economy, endurance, lactate threshold, peak power

Given that the physiology of heine oxygenase-1 (HO-1) encompasses mitochondrial biogenesis, we tested the hypothesis that the HO-1 product, carbon monoxide (CO), activates mitochondrial biogenesis in skeletal muscle and enhances maximal oxygen uptake ([??].sub.2max]) in humans. In l0 healthy subjects, we biopsied the vastus lateralis and performed [??].sub.2max] tests followed by blinded randomization to air or CO breathing (1 h/day at 100 parts/million for 5 days), a contralateral muscle biopsy on day 5, and repeat [??].sub.2max] testing on day 8. Six independent subjects underwent CO breathing and two muscle biopsies without exercise testing. Molecular studies were performed by real-time RT-PCR, Western blot analysis, and immunochemistry. After [??].sub.2max] testing plus CO breathing, significant increases were found in mRNA levels for nuclear respiratory factor-1, peroxisome proliferator-activated receptor-[gamma] coactivator-1[alpha], mitochondrial transcription factor-A (Tfam), and DNA polymerase [gamma](Pol[gamma]) with no change in mitochondrial DNA (mtDNA) copy number or [??].sub.2max]. Levels of myosin heavy chain I and nuclear-encoded HO-1, superoxide dismutase-2, citrate synthase, mitofusin-1 and -2, and mitochondrial-encoded cytochrome oxidase subunit-I (COX-I) and ATPase-6 proteins increased significantly. None of these responses were reproduced by [??].sub.2max] testing alone, whereas CO alone increased Tfam and Pol[gamma] mRNA, and COX-I, ATPase-6, mitofusin-2, HO-1, and superoxide dismutase protein. These findings provide evidence linking the HO/CO response involved in mitochondrial biogenesis in rodents to skeletal muscle in humans through a set of responses involving regulation of the mtDNA transcriptosome and mitochondrial fusion proteins autonomously of changes in exercise capacity. heme oxygenase-1; superoxide dismutase-2; peroxisome proliferator-activated receptor-[gamma] coactivator-1[alpha]; nuclear respiratory factor-1; oxygen uptake

A thermodynamic approach is used to derive a relation between cardiac output and rate of oxygen consumption. As an example, the relation is used to calculate the cardiac output of a young woman exercising on a treadmill. The results can be understood by undergraduates without any previous knowledge of human physiology.

Traditionally, the estimation of oxygen consumption (V[O.sub.2]) at work using heart rate (HR) has required the determination of individual HR/V[O.sub.2] calibration curves in a separate exercise test in a laboratory (V[O.sub.2]-TRAD). Recently, a new neural network-, and heart rate variability-based method has been developed (Firstbeat PRO heartbeat analysis software) for the estimation of V[O.sub.2] without individual calibration (V[O.sub.2]-HRV). In the present study, the V[O.sub.2]-values by the V[O.sub.2]-HRV were compared with the values by V[O.sub.2]-TRAD in 22 postal workers. Within individuals the correlation between the two methods was high (range 0.80-0.99). The V[O.sub.2]-TRAD gave higher values of V[O.sub.2] compared to V[O.sub.2]-HRV (19%) especially during low physical activity work when non-metabolic factors may increase HR. When assessed in different HR categories, the smallest difference (11%), and highest correlations (range 0.83-0.99) in V[O.sub.2] between the methods were observed at higher HR levels. The results indicate that the V[O.sub.2]-HRV is a potentially useful method to estimate V[O.sub.2] in the field without laboratory calibration. Keywords: Oxygen consumption; Heart rate; Heart rate variability

The purpose of the present study was to evaluate the reliability of the oxygen consumption/heart rate ([VO.sub.2]/HR) relationship used to estimate energy expenditure during a workday. Before and after a 6-10h work shift, the [VO.sub.2]/HR relationship was measured in 57 workers (28 female, 29 male) in our laboratory. [VO.sub.2] was similar before and after the shift at HR of 100 and 125 beats per minute (bpm). However, the [VO.sub.2]/HR relation and perceived exertion (RPE) became less accurate after a work shift as VO2 and RPE were, respectively, increased at HR above 150 and 125 bpm. Increase of RPE for a same exercise intensity was higher in female subjects. Our results suggest good reliability of the [VO.sub.2]/HR relationship at HR usually found in workplaces. Keywords. [VO.sub.2]/HR relationship; Cardiovascular drift; Perceived exertion

The purpose of this study was to develop an accurate metabolic prediction equation for elliptical crosstrainer (ECT) exercise. Male and female (n = 40) subjects (M [+ or -] SD, age: 30 [+ or -] 7 yr.; height: 173 [+ or -] 11 cm; weight: 72.3 [+ or -] 13.8 kg; body composition: 18.3 [+ or -] 6.9%) completed two randomized testing sessions. Steady-state oxygen uptake ([VO.sub.2]) was measured, while subjects exercised on the ECT at nine separate workloads each testing session. Multiple regression analysis to predict steady-state [VO.sub.2] from ECT resistance, ECT cadence, and subjects' body mass resulted in the following model ([R.sup.2] = .783): Steady-state V[O.sub.2] = 3.5 + 0.15(Cadence) + 1.22 (Resistance) - 0.11(Weight). Both the standard error of the estimate (SEE) and total error (TE) for the prediction of steady state [VO.sub.2] under all ECT workload conditions combined were 2.8 mL/kg/min. The SEE and TE values are similar to those previously reported in the literature regarding the accuracy of metabolic equations for other exercise modalities. These findings support the use of the equation developed in the present study to predict steady-state [VO.sub.2] for ECT exercise.

How animals manage their oxygen stores during diving and other breath-hold activities has been a topic of debate among physiologists for decades. Specifically, while the behavior of free-ranging diving animals suggests that metabolism during submersion must be primarily aerobic in nature, no studies have been able to determine their rate of oxygen consumption during submersion (V[O.sub.2]D) and hence prove that this is the case. In the present study, we combine two previously used techniques and develop a new model to estimate V[O.sub.2]D accurately and plausibly in a free-ranging animal and apply it to data for macaroni penguins (Eudyptes chrysolophus) as an example. For macaroni penguins at least, V[O.sub.2]D can be predicted by measuring heart rate during the dive cycle and the subsequent surface interval duration. Including maximum depth of the dive improves the accuracy of these predictions. This suggests that energetically demanding locomotion events within the dive combine with the differing buoyancy and locomotion costs associated with traveling to depth to influence its cost in terms of oxygen use. This will in turn effect the duration of the dive and the duration of the subsequent recovery period. In the present study, V[O.sub.2]D ranged from 4 to 28 ml x [min.sup.-1] x [kg.sup.-1], indicating that, at least as far as aerobic metabolism was concerned, macaroni penguins were often hypometabolic, with rates of oxygen consumption usually below that for this species resting in water (25.6 ml x [min.sup.-1] x [kg.sup.-1]) and occasionally lower than that while resting in air (10.3 ml x [min.sup.-1] x [kg.sup.-1]). penguin; model; oxygen stores; hypometabolism doi: 10.1152/ajpregu.00691.2006

The doubly labeled water (DLW) method for the measurement of the field metabolic rate (FMR) of free-ranging vertebrates has limitations that are most evident when dealing with very small mammals, such as the nectarivorous marsupial honey possum (Tarsipes rostratus), that exhibit high metabolic rates and elevated rates of water turnover. We tested the efficacy of the radioisotope rubidium-86 ([sup.86]Rb) as an alternative method for estimating FMR in this species in winter in Scott National Park in extreme southwestern Western Australia. We carried out a trial with 58 honey possums injected with a cocktail containing [sup.86]Rb, tritium, and oxygen-18 and correlated estimates of the FMR using the DLW method with repetitive measurements of the biological elimination rate constant ([k.sub.b]) of [sup.86]Rb. The 2 variables were significantly correlated and a linear regression explained 86% of the variation, which increased to 91% with a power curve fit to the data. Successive measurements of [k.sub.b] in individuals that were repeatedly recaptured over a 12-day period did not differ significantly, nor did the time interval between release and recapture affect the estimate of [k.sub.b]. The mean error involved in predicting the FMR from the kb for [sup.86]Rb was less than 5% and of the same order of magnitude as for the error inherent in the DLW method itself. Although the basic mechanism is unknown, the major advantages of the [sup.86]Rb method include the much longer time span over which animals may be recaptured and still provide reliable data, and the absence of the need to collect blood from the injected animals. We suggest that further research measuring the [k.sub.b]s of radioisotopes such as [sup.86]Rb in other species may lead to viable alternatives for the measurement of FMRs in very small mammals with high rates of metabolism and water turnover. Key words: doubly labeled water, field metabolic rate, marsupial, oxygen-18, rubidium-86, Tarsipes

The development and application of a methodology for measurement of oxygen within single mammalian cells are presented, which employ novel macromolecular near infrared (NIR) oxygen probes based on new metalloporphyrin dyes. The probes, which display optimal spectral characteristics and sensitivity to oxygen, excellent photostability, and low cytotoxicity and phototoxicity, are loaded into cells by simple transfection procedures and subsequently analyzed by high-resolution fluorescence microscopy. The methodology is demonstrated by sensing intracellular oxygen in different mammalian cell lines, including A549, Jurkat, and HeLa, and monitoring rapid and transient changes in response to mitochondrial uncoupling by valinomycin and inhibition by antimycin A. Furthermore, the effect of ryanodine receptor-mediated [Ca.sup.2+] influx on cellular oxygen uptake is shown by substantial changes in the level of intracellular oxygen. The results demonstrate the ability of this technique to measure small, rapid, and transient changes in intracellular oxygen in response to different biological effectors. Moreover, this technique has wide ranging applicability in cell biology and is particularly useful in the study of low oxygen environments (cellular hypoxia), mitochondrial and cellular (dys)function, and for therapeutic areas, such as cardiovascular and neurological research, metabolic diseases, and cancer. metalloporphyrin; mitochondrial function; uncoupling

Bioenergetic interpretations of energy transfer specify that rapid anaerobic, substrate-level adenosine triphosphate (ATP) turnover with lactate production is not appropriately represented by an oxygen uptake measurement. Two types of weight training, 60% of 1 repetition maximum (1RM) with repetitions to exhaustion and 80% of 1RM with limited repetitions, were compared to determine if blood lactate measurements, as an estimate of rapid substrate-level ATP turnover, provide a significant contribution to the interpretation of total energy expenditure as compared with oxygen uptake methods alone. The measurement of total energy expenditure consisted of blood lactate, exercise oxygen uptake, and a modified excess postexercise oxygen consumption (EPOC); oxygen uptake-only measurements consisted of exercise oxygen uptake and EPOC. When data from male and female subjects were pooled, total energy expenditure was significantly higher for reps to exhaustion (arm curl, +27 kJ; bench press, +27 kJ; leg press, +38 kJ; p < 0.03) and limited reps (arm curl, +12 kJ; bench press, +23 kJ; leg press, + 24 kJ; p < 0.05) when a separate measure of blood lactate was part of the interpretation. When the data from men and women were analyzed separately, blood lactate often made a significant contribution to total energy expenditure for reps to exhaustion (endurance-type training), but this trend was not always statistically evident for the limited reps (strength-type training) protocol. It is suggested that the estimation of total energy expenditure for weight training is improved with the inclusion, rather than the omission, of an estimate of rapid anaerobic substrate-level ATP turnover. KEY WORDS. anaerobic energy expenditure, excess postexercise oxygen consumption, exercise oxygen uptake

Byline: Ludger Bahlmann (1), Martin Misfeld (2), Stephan Klaus (1), Alexander Leptien (1), Matthias Heringlake (1), Peter Schmucker (1), Hans-Hinrich Sievers (2), Urban Ungerstedt (3), Ernst-Guenther Kraatz (2) Keywords: Coronary diseases; Oxygen consumption; Energy metabolism; Hypoxia; Cardioplegia; Mitochondria Abstract: Purpose Microdialysis allows the biochemical analysis of interstitial fluids of nearly every organ as a bedside procedure. This technique could be useful to reveal data about the myocardial metabolism during cardiopulmonary bypass in human coronary artery bypass graft (CABG) surgery. Methods In 17 patients undergoing CABG a myocardial microdialysis catheter (CMA 70, CMA/Microdialysis AB, Sweden) was inserted in the apical region of the beating heart. Microdialysis measurements were performed at timed intervals before, during, and after cardiopulmonary bypass (CPB). The concentrations of lactate and pyruvate were analyzed semi-continuously. Results During CPB the myocardial lactate- pyruvate- ratio (LPR) rose from an initial 11 (8--15) to 33 (29--41) (P Conclusion Using the microdialysis technique it was possible to analyze myocardial metabolic changes during CABG. The course of myocardial LPR as a sensitive indicator of the myocardial redox state showed profound changes during and after CPB. We propose the microdialysis technique as an additional monitoring tool in CABG. Author Affiliation: (1) Department of Anesthesiology, Medical University of Lubeck, Ratzeburger Allee 160, 23538 , Lubeck, Germany (2) Department of Cardiac Surgery, Medical University of Lubeck, Lubeck, Germany (3) Department of Pharmacology, Karolinska Institute, Stockholm, Sweden Article History: Registration Date: 27/01/2004 Received Date: 28/02/2003 Accepted Date: 15/10/2003 Online Date: 24/02/2004

We investigated the role of nitric oxide (NO) in the control of myocardial [O.sub.2] consumption in Fischer 344 rats. In Fischer rats at 4, 14, and 23 mo of age, we examined cardiac function using echocardiography, the regulation of cardiac 02 consumption in vitro, endothelial NO synthase (eNOS) protein levels, and potential mechanisms that regulate superoxide. Aging was associated with a reduced ejection fraction [from 75 [+ or -] 2% at 4 mo to 66 [+ or -] 3% (P < 0.05) at 23 mo] and an increased cardiac diastolic volume [from 0.60 [+ or -] 0.04 to 1.00 [+ or -] 0.10 ml (P < 0.01)] and heart weight (from 0.70 [+ or -] 0.02 to 0.90 [+ or -] 0.02 g). The NO-mediated control of cardiac [O.sub.2] consumption by bradykinin or enalaprilat was not different between 4 mo (36 [+ or -] 2 or 34 [+ or -] 3%) and 14 mo (29 [+ or -] 1 or 25 [+ or -] 3%) but markedly (P < 0.05) reduced in 23-mo-old Fischer rats (15 [+ or -] 3 or 7 [+ or -] 2%). The response to the NO donor S-nitroso-N-acetyl penicillamine was not different across groups (35%, 35%, and 44%). Interestingly, the eNOS protein level was not different at 4, 14, and 23 mo. The addition of tempol (1 mmol/l) to the tissue bath eliminated the depression in the control of cardiac [O.sub.2] consumption by bradykinin (25 [+ or -] 3%) or enalaprilat (28 [+ or -] 3%) in 23-mo-old Fischer rats. We next examined the levels of enzymes involved in the production and breakdown of superoxide. The expression of Mn SOD, Cu/Zn SOD, extracellular SOD, and p[67.sup.phox], however, did not differ between 4- and 23-mo-old rats. Importantly, there was a marked increase in gp[91.sup.phox], and apocynin restored the defect in NO-dependent control of cardiac [O.sub.2] consumption at 23 mo to that seen in 4-mo-old rats, identifying the role of NADPH oxidase. Thus increased biological activity of superoxide and not decreases in the enzyme that produces NO are responsible for the altered control of cardiac [O.sub.2] consumption by NO in 23-mo-old Fischer rats. Increased oxidant stress in aging, by decreasing NO bioavailability, may contribute not only to changes in myocardial function but also to altered regulation of vascular tone and the progression of cardiac or vascular disease. nitric oxide; Western blotting; tempol; mitochondria; SOD1; SOD2; SOD3; p[67.sup.phox]; gp[91.sup.phox]; apocynin

Research related to the effects of certain interventions on brain tissue oxygen monitoring was presented in part I: 'Research and Usefulness in Critical Care.' (1) In this article, we continue [...]

Objective The purpose of this study was to test a new handheld device, the BodyGem (HealtheTech Inc., Golden, CO), that measures resting metabolic rate (RMR). Subjects/design Sixty-three adults (43 women, 20 men) (mean±SD, age 41.3±11.2 years and body mass index, 26.5±6.6 kg/[m.sup.2]) were tested during two separate sessions within a 2-week period, and, in each session, two BodyGem and two Douglas bag RMR measurements were made in a random and counterbalanced order. Main outcome measures Resting oxygen consumption and energy expenditure. Statistical analyses performed A 2 (methods) X 4 (time points) repeated measures ANOVA, Pearson product-moment coefficients, Bland-Altman plots. Results Within session reliability for measurement of [O.sub.2], consumption was high on both days for the BodyGem (r=0.97). During the 4 single tests, BodyGem and Douglas bag [O.sub.2] consumption values were significantly correlated (r=0.81-0.87), with SEEs ranging from 22 to 28 mL * [min.sup.-1]. Mean [O.sub.2] consumption and RMR values for all 4 tests were 241±46 and 240±45 mL * [min.sup.-1] (r=0.91, SEE 18.7 mL * [min.sup.-1]) and 1,657±324 and 1,650±307 kcals * [day.sup.-1] (r=0.91, SEE 134 kcals * [day.sup.-1]) for the BodyGem and Douglas bag methods, respectively. Applications/conclusions These data indicate that the BodyGem is an accurate and reliable device for measuring oxygen consumption and calculating RMR during repeated tests within a day, single tests on separate days, or when measurements are averaged. J Am Diet Assoc. 2003;103:588-593., Energy expenditure is commonly divided into three components: resting metabolic rate (RMR), physical activity, and thermogenesis induced by food intake, exposure to cold, and other stressors (1). Measurement of energy [...]

Purpose: This study investigated the physiological responses of stroke survivors to a 16-week program of moderate aerobic and anaerobic exercise. Method: Forty participants who were a minimum of 6 months [...]

Regional myocardial blood flow (MBF) can be assessed noninvasively with dynamic positron emission tomography (PET) and [sup.13]N-ammonia or [sup.11]C-acetate. The latter can also be used to estimate the myocardial oxygen consumption (MVO2) from the same time-activity curve. In this work, we explore the feasibility of such techniques for evaluating myocardial parameters in normal and ischemic rats (~350 g) by dynamic imaging with the Sherbrooke small animal PET scanner. Scans were acquired in list mode for [sup.13]N-ammonia and [sup.11]C-acetate as two consecutive 15-min dynamic scans separated by a 5-min interval, without moving the rat from the scanner. Regions of interest (ROIs) were defined on four segments of the myocardium to extract the time-activity curves. Three-compartment models were applied to fit the [sup.13]N-ammonia and [sup.11]C-acetate data with three and four rate constants, respectively, plus blood volume. A reasonable agreement was observed between MBF estimates extracted from [sup.13]N-ammonia and [sup.11]C-acetate. MVO2 estimates, as given by the [k.sub.2] rate constant, were obtained with good reproducibility, indicating that myocardial metabolism can reliably be assessed concurrently with MBF using [sup.11]C-acetate. It is concluded that myocardial blood flow and oxygen consumption can be evaluated in rats with small animal PET scanners through high-rate, list-mode, dynamic imaging and kinetic modeling of [sup.13]N-ammonia and [sup.11]C-acetate. Index Terms--11C-acetate, 13N-ammonia, heart, myocardium, oxygen consumption, perfusion, positron emission tomography (PET), rat, small animal.

This article discusses the relationship between walking backwards, oxygen consumption, and motor learning. An analysis of energy metabolism and walking speed measurements is presented.

Byline: S. McLellan (1), T. Walsh (1), A. Burdess (1), A. Lee (1) Keywords: Pulmonary gas exchange Indirect calorimetry Oxygen consumption Carbon dioxide/metabolism Reproducibility of results Artificial respiration Abstract: Abstract Objective. To compare the M-COVX and the Deltatrac II metabolic monitors under clinical conditions. Design. Prospective clinical comparison. Setting. A general Intensive Care Unit of a university hospital. Patients. Twenty mechanically ventilated critically ill patients. Interventions. The monitors were compared at FiO.sub.2 0.3, 0.5, and 0.7 in each patient where possible. Measurements and results. Pulmonary gas exchange measurements were recorded using the two monitors sequentially (Deltatrac.sub.before, M-COVX, Deltatrac.sub.after). Each measurement consisted of five consecutive 1-min readings of VO.sub.2 and VCO.sub.2. We compared the Deltatrac.sub.before with the Deltatrac.sub.after and the mean of the Deltatrac with the M-COVX. There was no clinically significant bias between the two monitors for VO.sub.2 or VCO.sub.2 but the limits of agreement (LOA) were wide (bias +-95% LOA: VCO.sub.2 --13+-30 ml/min, --8+-36 ml/min, 7+-50 ml/min VO.sub.2 --7+-50 ml/min, --5+-56 ml/min, 6+-64 ml/min, at FiO.sub.2 0.3, 0.5, and 0.7, respectively). The Deltatrac before and after measurements displayed good agreement for VCO.sub.2 but poorer agreement for VO.sub.2 (bias+-95% LOA: VCO.sub.2 0+-18 ml/min, --6+-16 ml/min, --1+-12 ml/min VO.sub.2 2+-12 ml/min, 3+-38 ml/min, 10+-42 ml/min, at FiO.sub.2 0.3, 0.5, and 0.7, respectively). Using within-patient standard deviation as a measure of reproducibility suggested that for VO.sub.2 the M-COVX performed better than the Deltatrac at high FiO.sub.2, and for VCO.sub.2 Deltatrac was better at lower FiO.sub.2. Conclusions. The M-COVX is a suitable integrated device for measuring metabolic gas exchange in ventilated patients. Author Affiliation: (1) Department of Anaesthetics, Critical Care & Pain Medicine, Royal Infirmary of Edinburgh, Edinburgh EH3 9YW, Scotland, UK Article History: Received Date: 30/05/2001 Accepted Date: 02/04/2002 Article note: Electronic Publication

This article investigates the relationship between carbohydrate supplementation and exercise performance. An analysis of body mass index, heart rate and oxygen consumption measurements is presented.

Our goal was to determine whether mice genetically altered to lack either creatine kinase (M/MtC[K.sup.-/-]) or adenylate kinase (A[K.sup.-/-]) show altered properties in the dynamic regulation of myocardial oxygen consumption (M[Vo.sub.2]). We measured contractile function, oxygen consumption, and the mean response time of oxygen consumption to a step increase in heart rate [i.e., mitochondrial response time ([t.sub.mito])] in isolated Langendorff-perfused hearts from wild-type (n = 6), M/MtC[K.sup.-/-] (n = 6), and A[K.sup.-/-] (n = 4) mice. Left ventricular developed pressure was higher in M/MtC[K.sup.-/-] hearts (88.2 [+ or -] 6.8 mmHg) and lower in A[K.sup.-/-] hearts (46.7 [+ or -] 9.4 mmHg) compared with wild-type hearts (60.7 [+ or -] 10.1 mmHg) at the basal pacing rate. Developed pressure fell slightly when heart rate was increased in all three groups. Basal M[Vo.sub.2] at 300 beats/min was 19.1 [+ or -] 2.4, 19.4 [+ or -] 1.5, and 16.3 [+ or -] 1.9 [micro]mol * [min.sup.-1] * g dry [wt.sup.-1] for M/MtC[K.sup.-/-], A[K.sup.-/-], and wild type, respectively, which increased to 25.5 [+ or -] 3.7, 25.4 [+ or -] 2.6, and 22.0 [+ or -] 2.6 [micro]mol * [min.sup.-1] * [g.sup.-1], when heart rate was increased to 400 beats/min. The [t.sub.mito] was significantly faster in M/MtC[K.sup.-/-] hearts: 3.0 [+ or -] 0.3 versus 7.3 [+ or -] 0.6 and 8.0 [+ or -] 0.4 s for M/MtC[K.sup.-/-], A[K.sup.-/-], and wild type hearts, respectively. Our results demonstrate that M[Vo.sub.2] of M/MtC[K.sup.-/-] hearts adapts more quickly to an increase in heart rate and thereby support the hypothesis that creatine kinase acts as an energy buffer in the cytosol, which delays the energy-related signal between sites of ATP hydrolysis and mitochondria. oxygen consumption; mitochondria; metabolic wave

This article examines the relationship between exercise intensity and salivary hydrocortisone levels. An analysis of oxygen consumption, body composition, and heart rate measurements is presented.

This article discusses the relationship between gender, aerobic fitness, and energy metabolism in martial arts participants. An analysis of heart rate measurements, oxygen consumption, and weight loss is presented.

This article examines the impact of an exercise training program on potential firefighters' physical fitness ability levels. An analysis of recruits' oxygen consumption levels, flexibility, grip strength, and body mass index is presented.

This article discusses the relationship between oxygen consumption, energy metabolism, and aerobic dance bench stepping. An analysis of body weight, heart rate, and body height is presented.

This article discusses the relationship between creatine supplementation, anaerobic exercise, and fatigue. An analysis of participants' body weight, power output, and oxygen consumption measurements is presented

This article discusses the relationship between diet, body composition, and maximum oxygen consumption. An analysis of energy metabolism, physical fitness, and blood lipid levels is presented.

Weind, K. L., D. R. Boughner, L. Rigutto, and C. G. Ellis. Oxygen diffusion and consumption of aortic valve cusps. Am J Physiol Heart Circ Physiol 281: H2604-H2611, 2001.-- To maintain tissue oxygenation, normal aortic valves contain a vascular bed where tissue thickness is greatest. Avascular 'living' tissue-engineered heart valves have been proposed, yet little information exists regarding the magnitude of valve tissue metabolic activity or oxygen requirements. We therefore set out to measure the oxygen diffusivity ([Do.sub.2]) and oxygen consumption ([Vo.sub.2]) of seven porcine aortic valve cusps in vitro at 37 [degrees] C using a chamber with a Clark oxygen sensor. Mean [Do.sub.2] and [Vo.sub.2] were 1.06 x [10.sup.] [cm.sup.2]/s and 3.05 x [10.sup.-5].ml [O.sub.2].ml [tissue.sup.-1].[s.sup.-1], respectively. When modeled as a three-layered structure by using these values and a boundary condition of 100 mmHg at both surfaces, the average aortic cusp predicted a central mean [Po.sub.2] of 27 mmHg (range of 0-50 mmHg). The [Do.sub.2] value obtained was similar to that found for other vascular structures, but because our studies were carried out in vitro, the [Vo.sub.2] measurements may be lower than that required by the functioning valves. These values provide an initial understanding of the oxygen supply possible from the cusp surfaces and the oxygen needs of the tissue. tissue engineering; metabolic activity Received 27 March 2001; accepted in final form 9 August 2001

A trienzyme sensor for the amperometric determination of acetic acid was prepared by immobilizing acetate kinase (AK), pyruvate kinase (PK), and pyruvate oxidase (PyOx) on a poly(dimethylsiloxane) (PDMS)-coated electrode. AK catalyzes the phospho-transferring reaction between acetic acid and ATP to form ADP; PK, the phospho-transferring reaction between ADP and phosphoenolpyruvate to form pyruvic acid; and PyOx, the oxidation of pyruvic acid with oxygen. The oxygen consumption could be monitored by using the PDMS-coated electrode without interference from the PyOx reaction product, hydrogen peroxide. Thus, the concentration of acetic acid (5 [micro]M-0.5 mM) could be determined from the decrease in the cathodic current at -0.4 V vs Ag/AgCl. This is the first example of a biosensor that can be used for the determination of acetic acid in ethanol-containing food samples. The acetate-sensing electrode could be used for more than one month.

Byline: Tai-Fai Fok (1), Goldie Gu (1), Ka-Fai To (2), Feng Xu (1), Pak-Cheung Ng (1), Jane Yin (1) Keywords: Oxygen consumption Lung Rabbit Animal Chronic lung injury Acute lung injury Abstract: Objective: To study the oxygen consumption by lungs with acquired acute and chronic injury in a rabbit model. Design: A non-randomized controlled animal study. Subjects and method: Three groups of White New Zealand rabbits were studied to determine the oxygen consumption of the lungs. Group 1 (n=21, controls) consisted of healthy rabbits with normal lungs. The rabbits in group 2 (n=14) had sustained acute lung damage induced by subcutaneous N-nitroso-N-methylurethane and those in group 3 (n=9) had sustained chronic lung damage inflicted by a single dose of intra-tracheal bleomycin. Pulmonary oxygen consumption was estimated from the difference between the whole body oxygen consumption, measured by indirect calorimetry, and systemic oxygen consumption estimated by the Fick method. Measurements and results: Both acute and chronic lung-damaged groups had significantly greater pulmonary oxygen consumption than the control group, both as absolute values [control vs acute vs chronic: 0.25 (0.04) vs 0.76 (0.10) vs 1.77 (0.21) ml/kg per min, p Author Affiliation: (1) Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong (2) Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong Article History: Received Date: 19/11/2000 Accepted Date: 15/06/2001 Article note: Final revision received: 22 May 2001 Electronic Publication

Byline: D. Penny (1), T. Sano (1), J. Smolich (1) Keywords: Adrenergic agonists Adrenergic antagonists Brown fat Body temperature regulation Oxygen consumption Oxygen delivery Abstract: Objective: To determine: 1) if dobutamine elicited a thermogenic response during postnatal development and 2) if this response impacted on the balance between systemic O.sub.2 delivery (DO.sub.2) and O.sub.2 consumption (VO.sub.2), and involved one or a combination of adrenoceptor subtypes. Design: Prospective non-randomized unblinded study. Setting: University research laboratory. Subjects: Thirty-five Border-Leicester cross lambs used in a main study performed at 1--2 days (n=7), 7--10 days (n=7), and 6--8 weeks (n=8), and in a adrenoceptor blockade substudy performed at 1--2 days (n=13). Interventions: Lambs were instrumented under anaesthesia and dobutamine was infused at incremental rates of 1--40 Aug/kg per minute. In separate subgroups of 1--2 day-old lambs, dobutamine was infused after selective or combined [alpha].sub.1, [beta].sub.1, and [beta].sub.2-adrenoceptor blockade. Measurements: Cardiac output, aortic and pulmonary arterial blood gases, and body temperature were measured. DO.sub.2 and VO.sub.2 were calculated. Main results: Dobutamine increased DO.sub.2 similarly at all three ages. Dobutamine also increased VO.sub.2 in the absence of muscle shivering, but the average rise in 1--2 day-old lambs was sevenfold to 12-fold greater (P Author Affiliation: (1) Centre for Heart and Chest Research, Monash University Department of Medicine, Monash Medical Centre, Monash University, 246 Clayton Road, Clayton, Victoria, Australia, 3168 (2) Institute of Reproduction and Development, Monash University, Victoria, Australia (3) Department of Cardiology, Royal Children's Hospital, Victoria, Australia Article History: Received Date: 07/09/2000 Accepted Date: 22/06/2001 Article note: Final revision received: 21 June 2001 Electronic Publication

Results show that the oxygen consumption rate by the deep-waters of the Eastern Mediterranean is much higher, which may be due to high temperature conditions prevailing in deep waters. However, the circulation model shows only moderate differences from the previous data.

This article examines the effects of aerobic and resistance training at varying levels of intensity on the rate of resting energy metabolism in women. Findings indicate that the exercise mode and training intensity did not significantly affect resting metabolic rate.

Results demonstrate that Manila clam cannot maintain normal metabolic activities at a salinity regime lower than 15% as indicated by the oxygen-consumption rhythms. At 5% salinity for seven days, all clams are dead.

Byline: Masako Nogami (1), Takeshi Matsuno (2), Takehiro Nakamura (3), Tadashi Fukumoto (4) Keywords: Ohmura Bay; net oxygen consumption rate; T-DO diagram Abstract: We have observed the temporal variation of oxygen deficient water with short time scale (less than a few days) in the central area of Ohmura Bay, Kyushu, Japan, in summer, 1995 and 1996. The vertical profiles of temperature were similar to those of dissolved oxygen. We noticed a linear relation between temperature and dissolved oxygen in the bottom layer, and applied the T-DO relation to estimate the net oxygen consumption rate, rather than direct evaluation of the advection and diffusion. Oxygen consumption rate just above the bottom was estimated to be about 0.21 g O.sub.2 [m.sup.-3]day.sup.-1 in July 1995, and about 0.28 g O.sub.2 [m.sup.-3]day.sup.-1 in August 1996. The net oxygen consumption rate estimated for the bottom layer below the second thermocline was about 0.61 g O.sub.2 [m.sup.-3]day.sup.-1 with variability from 0.55 to 0.66 g O.sub.2 [m.sup.-3]day.sup.-1 during July 25 to 29, 1995. This is was about 0.64 g O.sub.2 [m.sup.-3]day.sup.-1 with variability from 0.18 to 1.4 g O.sub.2 [m.sup.-3]day.sup.-1 during August 22 to 30, 1996. The net oxygen consumption rates are about half of those measured with a closed system in the Seto Inland Sea. Author Affiliation: (1) Graduate School of Marine Science and Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki, 852-8521, Japan (2) Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan (3) Faculty of Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki, 852-8521, Japan (4) Nishimatsu Construction Co., Ltd., 2570-4 Shimotsuruma, Yamato, Kanagawa, 242-0001, Japan Article History: Registration Date: 07/10/2004

Young women participants were required to engage in a series of intense weight lifting tasks. Post-exercise measurements indicated an elevation of resting metabolic rate and fat oxidation during a 16-hour recovery period.

Peak oxygen consumption (VO(sub 2) peak) was measured in 150 adult males (18-35 years old) in Bolivia, using a complete migrant study design to partition developmental from ancestral (genetic) effects of high-altitude (HA) exposure. High-altitude natives (HANs, Aymara/Quechua ancestry, n = 75) and low-altitude natives (LANs, European] North American ancestry, n = 75) were studied at high altitude (3,600-3,850 m) and near sea level (420 m). HAN and LAN migrant groups to a nonnative environment were classified as: multigeneration migrants, born and raised in a nonnative environment; child migrants who migrated to the nonnative environment during the period of growth and development (0-18 years old); and adult migrants who migrated after 18 years of age. Variability in VO(sub 2) peak due to high-altitude adaptation was modeled by covariance analysis, adjusting for fat-free mass and physical activity (training) differences between groups. A trend for increased VO(sub 2) peak with increasing developmental high-altitude exposure in migrant groups did not reach statistical significance, but low statistical power may have limited the ability to detect this effect. HANs and LANs born, raised, and tested at high altitude had similar VO(sub 2) peak values, indicating no genetic effect, or an effect much smaller than that reported previously in the literature. There was no functional correlation between forced vital capacity and VO(sub 2) peak, within or across groups. These results do not support the hypothesis that Andean HANs have been selected to express a greater physical work capacity in hypoxia. Am J Phys Anthropol 110:435-455, 1999. KEY WORDS: physical work capacity; human adaptation; Bolivia; exercise; migrant study design; physical activity level; hypoxia

This paper describes a method for detecting oxygen consumption of adherent cell cultures. The sensing is based on oxygen-dependent quenching of the phosphorescence of a Pt-porphyrin complex immobilized on microcarrier beads, which are used as the cell culture substrate. Bead injection, a recent variant of the flow injection technique, is used to pack an aliquot of the beads into a small sensing layer that can be easily and rapidly renewed. The technique is tested on a model system of Chinese Hamster Ovary M1 cells grown on Cytodex-3 microcarrier beads. Cellular respiration is monitored through O(sub 2) consumption measured across a period of 3 rain. The method is validated by detecting the impairment of aerobic metabolism Caused by 1.5 mM amobarbital. Further, it is shown to have enough precision to distinguish even more subtle changes, such as the increase in oxygen consumption caused by stimulation of the muscarinic m1 receptor with 100 (mu)M carbachol.

Luminescence-based imaging-fiber oxygen sensors (IFOSs) were utilized for the in situ measurement of oxygen consumption from intact perfused mouse hearts. IFOSs were fabricated using a technically expedient, photoinitiated polymerization reaction whereby an oxygen-sensitive polymer matrix was immobilized in a precise location on an imaging fiber's distal face. The oxygen-sensing layer used in this work comprised a transition metal complex, Ru[[([Ph.sub.2]phen).sub.3].sup.2+], entrapped in a gas-permeable photopolymerizable siloxane membrane (PS802). The transduction mechanism was based upon the oxygen collisional quenching of the ruthenium complex luminescence; detection was performed utilizing an epi-fluorescence microscope/charge coupled device imaging system. IFOS measurements from working mouse hearts were validated through concurrent, blind, ex situ blood gas analyzer (BGA) measurements. The BGA and IFOS methodologies were utilized successfully to measure oxygen concentrations in aortic and pulmonary artery perfusates from the working mouse heart before and after isoproterenol administration. Coupled with coronary-flow measurements, these data were used to calculate myocardial oxygen consumption. Regression analysis of measurements of myocardial oxygen consumption showed that there was a strong correlation between the values generated by the BGA sampling and those obtained via in situ IFOS methods. To our knowledge, this research represents the first report of in situ fiber-optic sensor monitoring of oxygen content from the intact, beating mouse heart.