- Email: [email protected]
Swim or eat? Swim and eat? The environment lays down the law. An investigation of metabolic prioritization in sea bass
S184
Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S171–S188
high demands on flexibility and precision of the predictive starts do not compromise their performance. On the contrary, archer fish predictive starts are among the fastest C-starts known so far among teleost fish. They are as fast and of identical temporal structure as archer fish escape C-starts, elicited in the very same individuals. This suggests that archer fish recruit their C-start escape network of identified reticulospinal neurons, or elements of it, to drive their predictive starts. doi:10.1016/j.cbpa.2007.01.398
A12.40 Intermittent hypobaric hypoxia induces changes at a different extent in biochemical parameters depending on muscle activity degree P. Panisello, S. Esteva, R. Torrella, T. Pagès, G. Viscor, (Universitat de Barcelona) We examined the effect of intermittent hypobaric hypoxia exposure (IHHE) in some biochemical markers of aerobic/ anaerobic metabolism such as lactate dehydrogenase (LDH), citrate synthase (CS), and myoglobin (Mb) in three different morphofunctional muscles: myocardium (MYO), diaphragm (DFG) and tibialis anterior (TA). The IHHE programme was performed into a hypobaric chamber (5000 m simulated altitude) consisting in daily 4-h sessions, during 5 days per week until completing 22 days of hypoxia exposure. Samples were taken at the end of the exposure period (IHHE group), 20 (POST20d) and 40 (POST40d) days after the end of programme and compared to a control group (CONT). LDH activity was significantly depressed in the MYO of IHHE, POST20d and POST40d groups compared with CONT. A reverse tendency was detected in TA muscle, but this increase was non-significant. No differences were found in DFG. Although, any modification was significant, CS showed an opposed trend to LDH, as expected, in all muscles. All muscles showed a trend to increase in Mb concentration, but only in exposed MYO these changes were significant. These results seem to indicate that morphofunctional modifications due to hypoxia in striated muscles are related not only to oxidative character but also to the degree of muscle activity along the IHHE program. doi:10.1016/j.cbpa.2007.01.399
A12.41 Swim or eat? Swim and eat? The environment lays down the law. An investigation of metabolic prioritization in sea bass H. Jourdan, G. Claireaux, D. Mc Kenzie, (Institut des Sciences de l'Evolution (C.N.R.S. Université Montpellier 2) Département de Biologie Intégrative)
In heterogeneous and variable aquatic ecosystems, the capacity to allocate oxygen between competing metabolic processes is a key element of adaptability. In this study, we investigated prioritization, within a metabolic budget, of two major organs systems: gut and muscles. The impacts of feeding on the rate of oxygen consumption (MO2) and swimming performance (measured as critical swimming speed, Ucrit) were investigating in sea bass under normoxic and hypoxic conditions. In normoxia, digestion of a meal (equivalent to 3% body mass) induced a 14% increase in MO2 above the fasted condition, at all speeds, but Ucrit remained unchanged. This reveals that, in normoxia, the metabolic budget is additive: the sea bass can meet the oxygen demands of digestion even when swimming at high speeds. Hypoxia reduced both metabolic scope and Ucrit by 10%. When hypoxic sea bass were fed, they exhibited an additive pattern of metabolic costs at low swimming speeds but maximum metabolic rates (i.e., oxygen consumption at Ucrit) were similar under fasted and fed conditions. Once again, we saw no change in swimming capacities. Therefore, in hypoxia, at high speeds, metabolic costs of digestion and activity are mutually exclusive, which is a compensatory allocation model. So there is a switch between additive and compensatory budgeting, probably corresponding to an energetic threshold. In conclusion, we have demonstrated that it is necessary to consider environmental conditions (in particular environmental oxygen levels) when analysing metabolic prioritization in sea bass. It remains to be seen whether this is also true of other fish. doi:10.1016/j.cbpa.2007.01.400
A12.42 Effects of feeding and hypoxia upon blood allocation during aerobic exercise in sea bass (Dicentrarchus labrax L.) A. Dupont-Prinet, G. Claireaux, D. McKenzie, (ISEM) The cardiovascular system has an essential role in the functional integrity of fish, through the transport of respiratory gases and nutrients. The aim of this study was to investigate the effects of feeding and hypoxia upon blood allocation, by the cardiovascular system, during aerobic exercise in a teleost, the sea bass (Dicentrarchus labrax L.). Sea bass (mass approximately 350 g) were anaesthetised (MS-222) and an acoustic flow probe (Transonic) was placed around the ventral aorta to measure total cardiac output. A second probe was placed around the coeliac and mesenteric arteries, to measure total blood flow to the gastrointestinal tract. After 48-h recovery from surgery, the fish were exercised at incremental speeds to fatigue, in a swimtunnel respirometer, in either normoxic water, or hypoxic water at 50% of air-saturation. During the swimming test, oxygen consumption, total cardiac output, and total blood flow to the gastrointestinal tract were recorded at each speed. The following day, each fish was force-fed with 3% body mass of filleted fish muscle. At 6 h after feeding, the fish was exposed to the same swimming test, to investigate how the fish allocated
Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S171–S188
high demands on flexibility and precision of the predictive starts do not compromise their performance. On the contrary, archer fish predictive starts are among the fastest C-starts known so far among teleost fish. They are as fast and of identical temporal structure as archer fish escape C-starts, elicited in the very same individuals. This suggests that archer fish recruit their C-start escape network of identified reticulospinal neurons, or elements of it, to drive their predictive starts. doi:10.1016/j.cbpa.2007.01.398
A12.40 Intermittent hypobaric hypoxia induces changes at a different extent in biochemical parameters depending on muscle activity degree P. Panisello, S. Esteva, R. Torrella, T. Pagès, G. Viscor, (Universitat de Barcelona) We examined the effect of intermittent hypobaric hypoxia exposure (IHHE) in some biochemical markers of aerobic/ anaerobic metabolism such as lactate dehydrogenase (LDH), citrate synthase (CS), and myoglobin (Mb) in three different morphofunctional muscles: myocardium (MYO), diaphragm (DFG) and tibialis anterior (TA). The IHHE programme was performed into a hypobaric chamber (5000 m simulated altitude) consisting in daily 4-h sessions, during 5 days per week until completing 22 days of hypoxia exposure. Samples were taken at the end of the exposure period (IHHE group), 20 (POST20d) and 40 (POST40d) days after the end of programme and compared to a control group (CONT). LDH activity was significantly depressed in the MYO of IHHE, POST20d and POST40d groups compared with CONT. A reverse tendency was detected in TA muscle, but this increase was non-significant. No differences were found in DFG. Although, any modification was significant, CS showed an opposed trend to LDH, as expected, in all muscles. All muscles showed a trend to increase in Mb concentration, but only in exposed MYO these changes were significant. These results seem to indicate that morphofunctional modifications due to hypoxia in striated muscles are related not only to oxidative character but also to the degree of muscle activity along the IHHE program. doi:10.1016/j.cbpa.2007.01.399
A12.41 Swim or eat? Swim and eat? The environment lays down the law. An investigation of metabolic prioritization in sea bass H. Jourdan, G. Claireaux, D. Mc Kenzie, (Institut des Sciences de l'Evolution (C.N.R.S. Université Montpellier 2) Département de Biologie Intégrative)
In heterogeneous and variable aquatic ecosystems, the capacity to allocate oxygen between competing metabolic processes is a key element of adaptability. In this study, we investigated prioritization, within a metabolic budget, of two major organs systems: gut and muscles. The impacts of feeding on the rate of oxygen consumption (MO2) and swimming performance (measured as critical swimming speed, Ucrit) were investigating in sea bass under normoxic and hypoxic conditions. In normoxia, digestion of a meal (equivalent to 3% body mass) induced a 14% increase in MO2 above the fasted condition, at all speeds, but Ucrit remained unchanged. This reveals that, in normoxia, the metabolic budget is additive: the sea bass can meet the oxygen demands of digestion even when swimming at high speeds. Hypoxia reduced both metabolic scope and Ucrit by 10%. When hypoxic sea bass were fed, they exhibited an additive pattern of metabolic costs at low swimming speeds but maximum metabolic rates (i.e., oxygen consumption at Ucrit) were similar under fasted and fed conditions. Once again, we saw no change in swimming capacities. Therefore, in hypoxia, at high speeds, metabolic costs of digestion and activity are mutually exclusive, which is a compensatory allocation model. So there is a switch between additive and compensatory budgeting, probably corresponding to an energetic threshold. In conclusion, we have demonstrated that it is necessary to consider environmental conditions (in particular environmental oxygen levels) when analysing metabolic prioritization in sea bass. It remains to be seen whether this is also true of other fish. doi:10.1016/j.cbpa.2007.01.400
A12.42 Effects of feeding and hypoxia upon blood allocation during aerobic exercise in sea bass (Dicentrarchus labrax L.) A. Dupont-Prinet, G. Claireaux, D. McKenzie, (ISEM) The cardiovascular system has an essential role in the functional integrity of fish, through the transport of respiratory gases and nutrients. The aim of this study was to investigate the effects of feeding and hypoxia upon blood allocation, by the cardiovascular system, during aerobic exercise in a teleost, the sea bass (Dicentrarchus labrax L.). Sea bass (mass approximately 350 g) were anaesthetised (MS-222) and an acoustic flow probe (Transonic) was placed around the ventral aorta to measure total cardiac output. A second probe was placed around the coeliac and mesenteric arteries, to measure total blood flow to the gastrointestinal tract. After 48-h recovery from surgery, the fish were exercised at incremental speeds to fatigue, in a swimtunnel respirometer, in either normoxic water, or hypoxic water at 50% of air-saturation. During the swimming test, oxygen consumption, total cardiac output, and total blood flow to the gastrointestinal tract were recorded at each speed. The following day, each fish was force-fed with 3% body mass of filleted fish muscle. At 6 h after feeding, the fish was exposed to the same swimming test, to investigate how the fish allocated