Estimating excess post-exercise oxygen consumption using multiple linear regression in healthy Korean adults: a pilot study

[Purpose]This pilot study aimed to develop a regression model to estimate the excess post-exercise oxygen consumption (EPOC) of Korean adults using various easy-to-measure dependent variables.[Methods]The EPOC and dependent variables for its estimation (e.g., sex, age, height, weight, body mass index, fat-free mass [FFM], fat mass, % body fat, and heart rate_sum [HR_sum]) were measured in 75 healthy adults ( 31 males, 44 females). Statistical analysis was performed to develop an EPOC estimation regression model using the stepwise regression method.[Results]We confirmed that FFM and HR_sum were important variables in the EPOC regression models of various exercise types. The explanatory power and standard errors of estimates (SEE) for EPOC of each exercise type were as follows: the continuous exercise (CEx) regression model was 86.3% (R²) and 85.9% (adjusted R²), and the mean SEE was 11.73 kcal, interval exercise (IEx) regression model was 83.1% (R²) and 82.6% (adjusted R²), while the mean SEE was 13.68 kcal, and the accumulation of short-duration exercise (AEx) regression models was 91.3% (R²) and 91.0% (adjusted R²), while the mean SEE was 27.71 kcal. There was no significant difference between the measured EPOC using a metabolic gas analyzer and the predicted EPOC for each exercise type.[Conclusion]This pilot study developed a regression model to estimate EPOC in healthy Korean adults. The regression model was as follows: CEx = -37.128 + 1.003 × (FFM) + 0.016 × (HR_sum), IEx = -49.265 + 1.442 × (FFM) + 0.013 × (HR_sum), and AEx = -100.942 + 2.209 × (FFM) + 0.020 × (HR_sum).     

Behaviour of growth hormone transgenic coho salmon Oncorhynchus kisutch in marine mesocosms assessed by acoustic tag telemetry

Underwater acoustic tag telemetry was used to assess behavioural differences between juvenile wild‐type (i.e. non‐transgenic, NT) and growth hormone (GH) transgenic (T) coho salmon Oncorhynchus kisutch in a contained simulated ocean environment. T O. kisutch were found across days to maintain higher baseline swimming speeds than NT O. kisutch and differences in response to feeding were detected between T and NT genotypes. This is the first study to assess behaviour of GH transgenic salmonids in a marine environment and has relevance for assessing whether behavioural effects of GH overexpression seen in freshwater environments can be extrapolated to oceanic phases of the life cycle.     

Oxygen uptake of growth hormone transgenic coho salmon during starvation and feeding

Oxygen uptake of growth hormone transgenic coho salmon Oncorhynchus kisutch was measured in individual fish with a closed-system respirometer and was compared with that of similar-sized non-transgenic control coho salmon during starvation and when fed a fixed ration or to satiation. Transgenic and control fish did not differ in their standard oxygen uptake after 4 days of starvation, although control fish had a higher routine oxygen uptake, scope for spontaneous activity and initial acclimation oxygen uptake. During feeding, transgenic fish ate significantly more than control fish, and had an overall oxygen uptake that was 1·7 times greater than control fish. When fish that had eaten the same per cent body mass were compared, transgenic fish had an oxygen uptake that was 1·4 times greater than control fish. Differences in oxygen uptake in growth hormone transgenic coho salmon and non-transgenic fish appear to be due to the effects of feeding, acclimation and activity level, and not to a difference in basal metabolism.     

Disease resistance, stress response and effects of triploidy in growth hormone transgenic coho salmon

Diploid and triploid coho salmon Oncorhynchus kisutch transgenic for growth hormone (GH) and control coho salmon were compared for differences in disease resistance and stress response. Resistance to the bacterial pathogen Vibrio anguillarum was not affected in transgenic fish relative to their non‐transgenic counterparts when they were infected at the fry stage, but was lower in transgenic fish when infected near smolting. Vaccination against vibriosis provided equal protection to both transgenic and non‐transgenic fish. Triploid fish showed a lower resistance to vibriosis than their diploid counterparts. Diploid transgenic fish and non‐transgenic fish appeared to show similar physiological and cellular stress responses to a heat shock. These studies provide information useful for both performance and ecological risk assessments of growth‐accelerated coho salmon.     

Effect of meal size on excess post-exercise oxygen consumption in fishes with different locomotive and digestive performance

Effects of feeding on pre-exercise VO₂ and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise were investigated in sedentary southern catfish, active herbivorous grass carp, omnivorous crucian carp, and sluggish omnivorous darkbarbel catfish to test whether feeding had different effects on EPOC and to compare EPOC in fishes with different ecological habits. For fasting fish, the pre-exercise and peak post-exercise VO₂ were higher and recovery rates were faster in crucian carp and grass carp compared to those of darkbarbel catfish and southern catfish. EPOC magnitudes of grass carp and southern catfish were significantly larger than those of crucian carp and darkbarbel catfish. Feeding had no significant effect on peak post-exercise VO₂, recovery rate, and EPOC magnitude in grass carp. Both the pre-exercise and peak post-exercise VO₂ increased with meal size, while the EPOC magnitude and duration decreased significantly in the larger meal size groups of crucian carp and southern catfish. In darkbarbel catfish, both the pre-exercise and peak post-exercise VO₂ increased with meal size, but the VO₂ increment elicited by exercise was larger in feeding groups compared with the fasting group. These results suggest that (1) the characteristics of the post-exercise VO₂ profile, such as peak post-exercise VO₂ and recovery rate, were closely related to the activity of fishes, whereas the EPOC magnitude was not and (2) the effects of feeding on EPOC were more closely related to the postprandial increase in VO₂.     

Assessing the capacity for compensatory growth in growth‐hormone transgenic coho salmon Oncorhynchus kisutch

The effect of feed cycling (consisting of periods of starvation followed by periods of refeeding to satiation) on compensatory growth was evaluated in growth hormone transgenic and non‐transgenic wild‐type coho salmon Oncorhynchus kisutch. The specific growth rate (G_SR) of feed‐restricted non‐transgenic O. kisutch was not significantly different from the G_SR of fully‐fed non‐transgenic O. kisutch during two refeeding periods, whereas the G_SR of feed‐restricted transgenic O. kisutch was significantly higher in relation to the G_SR of fully‐fed transgenic O. kisutch during the second refeeding period, but not during the first, indicating that growth compensation mechanisms are different between non‐transgenic and growth‐hormone (GH)‐transgenic O. kisutch and may depend on life history (i.e. previous starvation). Despite the non‐significant growth rate compensation in non‐transgenic O. kisutch, these fish showed a level of body mass catch‐up growth not displayed by transgenic O. kisutch.     

Disease resistance and health parameters of growth-hormone transgenic and wild-type coho salmon,Oncorhynchus kisutch

To extend previous findings regarding fish health and disease susceptibility of growth-enhanced fish, hematological and immunological parameters have been compared between growth hormone (GH) transgenic and wild-type non-transgenic coho salmon (Oncorhynchus kisutch). Compared to non-transgenic coho salmon, transgenic fish had significantly higher hematocrit (Hct), hemoglobin (Hb), mean cellular hemoglobin (MCH), mean cellular volume (MCV), and erythrocyte numbers, and lower white cell numbers. In addition, resistance to the bacterial pathogen Aeromonas salmonicida (causal agent of furunculosis) has been assessed between the strains. Higher susceptibility of transgenic fish to this disease challenge was observed in two separate year classes of fish. The present findings provide fundamental knowledge of the disease resistance on GH enhanced transgenic coho salmon, which is of importance for assessing the fitness of transgenic strains for environmental risk assessments, and for improving our understanding effects of growth modification on basic immune functions.     

Interaction of growth hormone overexpression and nutritional status on pituitary gland clock gene expression in coho salmon,Oncorhynchus kisutch

Clock genes are involved in generating a circadian rhythm that is integrated with the metabolic state of an organism and information from the environment. Growth hormone (GH) transgenic coho salmon, Oncorhynchus kisutch, show a large increase in growth rate, but also attenuated seasonal growth modulations, modified timing of physiological transformations (e.g. smoltification) and disruptions in pituitary gene expression compared with wild-type salmon. In several fishes, circadian rhythm gene expression has been found to oscillate in the suprachiasmatic nucleus of the hypothalamus, as well as in multiple peripheral tissues, but this control system has not been examined in the pituitary gland nor has the effect of transgenic growth modification been examined. Thus, the daily expression of 10 core clock genes has been examined in pituitary glands of GH transgenic (T) and wild-type coho salmon (NT) entrained on a regular photocycle (12L: 12D) and provided either with scheduled feeding or had food withheld for 60?h. Most clock genes in both genotypes showed oscillating patterns of mRNA levels with light and dark cycles. However, T showed different amplitudes and patterns of expression compared with wild salmon, both in fed and starved conditions. The results from this study indicate that constitutive expression of GH is associated with changes in clock gene regulation, which may play a role in the disrupted behavioural and physiological phenotypes observed in growth-modified transgenic strains.     

Intestinal morphology in growth hormone transgenic coho salmon

In two GH transgenic coho salmon Oncorhynchus kisutch , the surface area of the intestine was 2·2 times that of control salmon and the growth rate was about twice that of controls. It seems likely that the enhanced intestinal surface area is a compensatory feature that is manifested in fast growing salmonids.     

力竭性运动锻炼和饥饿对南方鲇运动后过量耗氧的影响

为了检验力竭性运动锻炼和饥饿是否对南方鲇Silurus meridonalis Chen维持能量消耗和无氧代谢能力产生影响,在25℃条件下测定了维持日粮(1.5%body mass per day)和饥饿条件下南方鲇15d力竭性锻炼(5min chasing)和随后5d恢复过程静止代谢率(VO2rest)和运动后过量耗氧(Excess post-exercise VO2,EPOC)的变化.另外两组非锻炼组分别作为摄食和饥饿对照组.实验过程中摄食和饥饿对照组VO2rest显著下降(P＜0.05),而摄食和饥饿对照组经过15d的锻炼显著上升(P＜0.05).经过5d的恢复2锻炼组VO2rest显著下降与对照组无显著差异.摄食和饥饿对照组力竭运动后代谢率峰值(VO2peak)在实验过程中显著下降(P＜0.05),而摄食和饥饿锻炼组经过15d没有显著变化.锻炼取消后2锻炼组VO2peak显著下降至对照组水平.各锻炼组和对照组间过量耗氧均无显著差异.实验提示:(1)锻炼导致VO2rest和VO2peak显著提高,但影响可塑性大,5d恢复期后影响消失;(2)锻炼导致力竭运动后代谢恢复速率加快,5d恢复期后锻炼影响依然存在;(3)对饥饿和摄食组,锻炼的生理影响相似,但饥饿组VO2rest对锻炼更为敏感.     

Salinity effects on oxygen consumption, gill Na+, K+-ATPase and ion regulation in juvenile coho salmon

The metabolic response of juvenile coho salmon Oncorhynchus kisutch to different salinities was examined, using whole-animal oxygen consumption rates and gill Na⁺, K⁺-ATPase activities as indicators of osmoregulatory energetics. Coho salmon smolts were acclimated to fresh water (FW), isosmotic salinity (ISO, 10‰) and sea water (SW, 28‰) and were sampled for up to 6 weeks for plasma levels of cortisol, glucose and ions (Na⁺, K⁺, Cl⁻), gill Na⁺, K⁺-ATPase activity and oxygen consumption rates. Following an initial adjustment period, plasma constituents in SW fish returned to near-FW values, indicating that the fish were acclimated to SW by day 21. Gill Na⁺, K⁺-ATPase activities on days 21 and 42 were lowest in ISO, higher in FW and highest in SW. This result is consistent with the idea that less energy would be required to maintain ion balance in an isosmotic environment, where the ionic gradients between extracellular fluid and water would be minimal. Oxygen consumption rates of swimming fish (1 body length s⁻¹), however, did not differ significantly between the three test salinities after 6 weeks. The results of this study suggest that the metabolic response of juvenile salmonids to changes in salinity is dependent on life-history stage (e.g. fry v . smolt), and that oxygen consumption rates do not necessarily reflect osmoregulatory costs.     

Effects of surgically implanted transmitters on swimming performance, food consumption and growth of wild Atlantic salmon parr

Experiments were conducted on wild Atlantic salmon Salmo salar parr to determine the effect of surgically implanted dummy transmitters on swimming performance, food consumption and growth. Swimming performance of tagged fish (tag 1·7–3·7% of fish mass) was similar to that of control fish 1, 5 and 10 days after surgery. Negative effects on growth, however, were found up to day 36 of a 45 day experiment (tag 0·9–2·6% of fish mass). Consumption rates were similar between tagged and control fish and did not explain differences in growth.     

The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption

Nine males with mean maximal oxygen consumption (VO2max) = 63.0 ml.kg-1.min-1, SD 5.7 and mean body fat = 10.6%, SD 3.1 each completed nine counterbalanced treatments comprising 20, 50 and 80 min of treadmill exercise at 30, 50 and 70% VO2max. The O2 deficit, 8 h excess post-exercise oxygen consumption (EPOC) and EPOC:O2 deficit ratio were calculated for all subjects relative to mean values obtained from 2 control days each lasting 9.3 h. The O2 deficit, which was essentially independent of exercise duration, increased significantly (P less than 0.05) with intensity such that the overall mean values for the three 30%, 50% and 70% VO2max workloads were 0.83, 1.89 and 3.09 l, respectively. While there were no significant differences (P greater than 0.05) between the three EPOCs after walking at 30% VO2max for 20 (1.01 l), 50 (1.43 l) and 80 min (1.04 l), respectively, the EPOC thereafter increased (P less than 0.05) with both intensity and duration such that the increments were much greater for the three 70% VO2max workloads (EPOC: 20 min = 5.68 l; 50 min = 10.04 l; 80 min = 14.59 l) than for the three 50% VO2max workloads (EPOC: 20 min = 3.14 l; 50 min = 5.19 l; 80 min = 6.10 l). An analysis of variance indicated that exercise intensity was the major determinant of the EPOC since it explained five times more of the EPOC variance than either exercise duration or the intensity times duration interaction. The mean EPOC:O2 deficit ratio ranged from 0.8 to 4.5 and generally increased with both exercise intensity and duration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of clay particles on the cutaneous exchange of oxygen across the chorion of Atlantic salmon eggs

Rates of oxygen consumption for Atlantic salmon Salmo salar embryos approaching hatching were determined. Values were recorded using a 'closed system' experimental set‐up. A magnetic stirrer was used to ensure that zones of oxygen depletion did not develop in the micro‐environment surrounding the respiring eggs. Recorded values of oxygen consumption ranged from 0·0024 to 0·0038 mg O₂ egg⁻¹ h⁻¹, with a mean consumption rate of 0·0032 mg O₂ egg⁻¹ h⁻¹. The values of oxygen consumption were similar to those reported in other studies using a closed system experimental set‐up, however, they were lower than those reported in a study adopting a flow‐through system. The introduction of clay‐sized sediment to the incubation chamber created a thin film (<1 mm) of sediment on the egg surface, and resulted in reduced rates of oxygen consumption. The additional 0·3 g of clay sediment reduced oxygen consumption by an average of 41% and the addition of a further 0·2 g of clay sediment reduced consumption by an average of 98%. Two explanations for the recorded reduction in consumption were proposed: (i) the creation of a low permeability seal around the eggs restricted the availability of oxygen to the incubating embryos and (ii) the clay‐sized fine sediment physically blocked the micro‐pore canals in the egg membrane, thereby restricting oxygen uptake.     

Oxygen consumption, ammonia excretion and protein use in response to thermal changes in juvenile Atlantic salmon Salmo salar

Experiments were designed to examine the effects of various temperature challenges on oxygen consumption and ammonia excretion rates and protein utilization in juvenile Atlantic salmon Salmo salar . Fish acclimated to 15° C were acutely and abruptly exposed to either 20 or 25° C for a period of 3 h. To simulate a more environmentally relevant temperature challenge, a third group of fish was exposed to a gradual increase in temperature from 15 to 20° C over a period of 3 h ( c. 1·7° C h⁻¹). Oxygen consumption and ammonia excretion rates were monitored before, during and after the temperature shift. From the ammonia excretion and oxygen consumption rates, protein utilization rates were calculated. Acute temperature changes (15–20° C or 15–25° C) caused large and immediate increases in the oxygen consumption rates. When the temperature was gradually changed ( i.e. 1·7° C h⁻¹), however, the rates of oxygen consumption and ammonia excretion were only marginally altered. When fish were exposed to warmer temperatures ( i.e. 15–20° C or 15–25° C) protein use generally remained at pre-exposure (15° C) levels. A rapid transfer back to 15° C (20–15° C or 25–15° C) generally increased protein use in S. salar . These results indicate that both the magnitude and the rate of temperature change are important in describing the physiological response in juvenile salmonids.     

Embryo survival and smolt to adult survival in second‐generation outbred coho salmon

Outbreeding depression was not detectable in observations of embryonic survival and of survival of smolts to adulthood relative to controls in coho salmon Oncorhynchus kisutch experimentally outbred over two generations by crossing fish from three widely separated populations. Survival in outbred coho salmon was not detectably less than that in second‐generation hybrid controls or second‐generation parental controls. Variation of embryonic survival was affected by the maternal source population and by individual females but not by the paternal source population or by individual males. Survival of smolts to adulthood at sea was greater in one second‐generation control group than in two others, but survival in second‐generation outbred groups was no less than in parental controls or hybrid controls.     

Gut size in GH‐transgenic coho salmon is enhanced by both the GHtransgene and increased food intake

Growth hormone transgenic coho salmon Oncorhynchus kisutch fed at the same ration level as non‐transgenic controls (Tc) had the same growth rate as non‐transgenic controls (Nt). In contrast, growth hormone transgenic coho salmon (Tf) fed ad libitum ate about twice as much and had much higher growth rates than the other two groups. The most obvious result was the significantly larger caeca in the Tf group relative to both Nt or pair‐fed Tc. The Tf fish had more caeca that were longer. The results suggested that the effect was indirect and the enlarged caeca required both the GHtransgene and hyperphagia to cause enlarged caecal capacity. A small part of the results, however, also suggested that there was a direct effect of the GHtransgene on some gut tissues, particularly the intestine.     

A three‐phase excess post‐exercise oxygen consumption in Atlantic salmon Salmo salar and its response to exercise training

The recovery of oxygen uptake to the standard metabolic rate (SMR) following exhaustive chasing exercise in Atlantic salmon Salmo salar parr occurred in three phases (rapid, plateau and slow). The initial recovery phase lasted 0·7 h and contributed 16% to the total excess post‐exercise oxygen consumption (EPOC). It was followed by a longer plateau phase that contributed 53% to the total EPOC. The slow recovery phase that completed recovery of SMR, which has not been reported previously, made a 31% contribution to the total EPOC. The plasticity of EPOC was demonstrated in exercise‐trained fish. Exercise training increased EPOC by 39% when compared with control fish (mean ± S.E., 877·7 ± 73·1 v . 629·2 ± 53·4 mg O₂ kg^?1, d.f. = 9, P <  0·05), with the duration of the plateau phase increasing by 38% (4·7 ± 0·58 v . 3·4 ± 0·16 h, d.f. = 9, P <  0·05) and the contribution of the slow phase to the total EPOC increasing by 80% (173·9 ± 23·9 v . 312·5 ± 50·4 mg O₂ kg^?1, d.f. = 9, P  < 0·05). As a result, the combination of the plateau and slow phases of exercise‐trained fish increased by 47% compared with control fish (756·6 ± 71·4 v . 513·6 ± 43·1 mg O₂ kg^?1; d.f. = 9, P  = 0·01). To substantiate the hypothesis that the plateau and slow recovery phase of EPOC was related to general metabolic recovery following exhaustive exercise, the time‐course for recovery of SMR was compared with previously published metabolite recovery profiles. The final phase of metabolic recovery was temporally associated with the final phases of gluconeogenesis, lactate oxidation and muscle intracellular pH regulation. Therefore, the plasticity of the latter phase of EPOC agreed with the known effects of exercise training in fishes.     

Transgenic salmon: tailoring the genome for food production

The production of transgenic salmon using gene transfer technology is described. Both antifreeze proteins and growth hormone genes have been successfully transferred. The expression, inheritance and phenotypes are examined using a wide variety of techniques. The development of new transgenics will be beneficial to aquaculture.     

The glutathione antioxidant system is enhanced in growth hormone transgenic coho salmon (<Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>)

Insertion of a growth hormone (GH) transgene in coho salmon results in accelerated growth, and increased feeding and metabolic rates. Whether other physiological systems within the fish are adjusted to this accelerated growth has not been well explored. We examined the effects of a GH transgene and feeding level on the antioxidant glutathione and its associated enzymes in various tissues of coho salmon. When transgenic and control salmon were fed to satiation, transgenic fish had increased tissue glutathione, increased hepatic glutathione reductase activity, decreased hepatic activity of the glutathione synthesis enzyme γ-glutamylcysteine synthetase, and increased intestinal activity of the glutathione catabolic enzyme γ-glutamyltranspeptidase. However, these differences were mostly abolished by ration restriction and fasting, indicating that upregulation of the glutathione antioxidant system was due to accelerated growth, and not to intrinsic effects of the transgene. Increased food intake and ability to digest potential dietary glutathione, and not increased activity of glutathione synthesis enzymes, likely contributed to the higher levels of glutathione in transgenic fish. Components of the glutathione antioxidant system are likely upregulated to combat potentially higher reactive oxygen species production from increased metabolic rates in GH transgenic salmon.