Lactate kinetics of rainbow trout during graded exercise: Do catheters affect the cost of transport?

Teulier, Loïc; Omlin, Teye; Weber, Jean‐Michel

doi:10.1242/jeb.091058

Cited by 16 publications

(22 citation statements)

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“…1B). Again, the increase in R d reduces the lactate load on the circulation by half (Teulier et al, 2013). These responses to environmental and functional hypoxia suggest that lactate accumulates because it cannot be processed as rapidly by oxidative tissues (red muscle, heart, gills and brain) as it is produced by anaerobic glycolysis in white muscle (Fig.…”

Section: Lactate Fluxes and Monocarboxylate Transportersmentioning

confidence: 95%

“…More recently, the lactate kinetics of rainbow trout have been characterized in more detail using continuous tracer infusion, a method that allows quantification of the rates of appearance (R a ) in the circulation and disappearance from it (R d ) separately. The effects of environmental hypoxia (Omlin and Weber, 2010), graded exercise (Teulier et al, 2013) and exogenous lactate supply (Omlin et al, 2014) on endogenous R a and R d lactate have been measured (Figs 1, 2). After 90 min of hypoxia (at 25% air saturation), lactate accumulates to 9 mmol l −1 in the circulation because of a mismatch in fluxes resulting from the more rapid rise in R a (+98%) than in R d (+52%) (Fig.…”

Section: Lactate Fluxes and Monocarboxylate Transportersmentioning

confidence: 99%

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Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Weber

Choi

Gonzalez

et al. 2016

Journal of Experimental Biology

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Muscle performance depends on the supply of metabolic fuels and disposal of end-products. Using circulating metabolite concentrations to infer changes in fluxes is highly unreliable because the relationship between these parameters varies greatly with physiological state. Quantifying fuel kinetics directly is therefore crucial to the understanding of muscle metabolism. This review focuses on how carbohydrates, lipids and amino acids are provided to fish muscles during hypoxia and swimming. Both stresses force white muscle to produce lactate at higher rates than it can be processed by aerobic tissues. However, lactate accumulation is minimized because disposal is also strongly stimulated. Exogenous supply shows that trout have a much higher capacity to metabolize lactate than observed during hypoxia or intense swimming. The low density of monocarboxylate transporters and their lack of upregulation with exercise explain the phenomenon of white muscle lactate retention. This tissue operates as a quasi-closed system, where glycogen stores act as an 'energy spring' that alternates between explosive power release during swimming and slow recoil from lactate in situ during recovery. To cope with exogenous glucose, trout can completely suppress hepatic production and boost glucose disposal. Without these responses, glycemia would increase four times faster and reach dangerous levels. The capacity of salmonids for glucoregulation is therefore much better than presently described in the literature. Instead of albumin-bound fatty acids, fish use lipoproteins to shuttle energy from adipose tissue to working muscles during prolonged exercise. Proteins may play an important role in fueling muscle work in fish, but their exact contribution is yet to be established. The membrane pacemaker theory of metabolism accurately predicts general properties of muscle membranes such as unsaturation, but it does not explain allometric patterns of specific fatty acids. Investigations of metabolic fuel kinetics carried out in fish to date have demonstrated that these ectotherms use several unique strategies to orchestrate energy supply to working muscles and to survive hypoxia.

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Section: Lactate Fluxes and Monocarboxylate Transportersmentioning

confidence: 95%

Section: Lactate Fluxes and Monocarboxylate Transportersmentioning

confidence: 99%

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Weber

Choi

Gonzalez

et al. 2016

Journal of Experimental Biology

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“…Therefore, it could potentially decrease metabolic rate (MO 2 ) because 15 to 30% less oxygen is needed to produce the same amount of ATP when oxidizing carbohydrates rather than lipids (38,47). This could result in a lower metabolic cost of transport (COT) measured as the amount of oxygen needed to move one unit body mass by one unit distance (42). Therefore, the goals of this study are 1) to quantify the effects of graded swimming on the glucose kinetics of rainbow trout, 2) to determine how the supply of exogenous glucose modulates the changes in glucose fluxes caused by exercise alone, and 3) to see whether exogenous glucose increases swimming performance (U crit ) or decreases COT.…”

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confidence: 99%

Coping with an exogenous glucose overload: glucose kinetics of rainbow trout during graded swimming

Choi

Weber

2016

American Journal of Physiology-Regulatory, Integrative and Comp

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This study examines how chronically hyperglycemic rainbow trout modulate glucose kinetics in response to graded exercise up to critical swimming speed (Ucrit), with or without exogenous glucose supply. Our goals were 1) to quantify the rates of hepatic glucose production (Ra glucose) and disposal (Rd glucose) during graded swimming, 2) to determine how exogenous glucose affects the changes in glucose fluxes caused by exercise, and 3) to establish whether exogenous glucose modifies Ucrit or the cost of transport. Results show that graded swimming causes no change in Ra and Rd glucose at speeds below 2.5 body lengths per second (BL/s), but that glucose fluxes may be stimulated at the highest speeds. Excellent glucoregulation is also achieved at all exercise intensities. When exogenous glucose is supplied during exercise, trout suppress hepatic production from 16.4 ± 1.6 to 4.1 ± 1.7 μmol·kg(-1)·min(-1) and boost glucose disposal to 40.1 ± 13 μmol·kg(-1)·min(-1). These responses limit the effects of exogenous glucose to a 2.5-fold increase in glycemia, whereas fish showing no modulation of fluxes would reach dangerous levels of 114 mM of blood glucose. Exogenous glucose reduces metabolic rate by 16% and, therefore, causes total cost of transport to decrease accordingly. High glucose availability does not improve Ucrit because the fish are unable to take advantage of this extra fuel during maximal exercise and rely on tissue glycogen instead. In conclusion, trout have a remarkable ability to adjust glucose fluxes that allows them to cope with the cumulative stresses of a glucose overload and graded exercise.

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“…Even with double PE50 aortic cannulations in rainbow trout of this size, there are no detectable effects on total swimming cost or maximal performance [61], although net swimming costs, minus resting metabolism, are elevated at speeds approaching U crit .…”

Section: Methodsmentioning

confidence: 86%

Resolving Shifting Patterns of Muscle Energy Use in Swimming Fish

Gerry

Ellerby

2014

PLoS ONE

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Muscle metabolism dominates the energy costs of locomotion. Although in vivo measures of muscle strain, activity and force can indicate mechanical function, similar muscle-level measures of energy use are challenging to obtain. Without this information locomotor systems are essentially a black box in terms of the distribution of metabolic energy. Although in situ measurements of muscle metabolism are not practical in multiple muscles, the rate of blood flow to skeletal muscle tissue can be used as a proxy for aerobic metabolism, allowing the cost of particular muscle functions to be estimated. Axial, undulatory swimming is one of the most common modes of vertebrate locomotion. In fish, segmented myotomal muscles are the primary power source, driving undulations of the body axis that transfer momentum to the water. Multiple fins and the associated fin muscles also contribute to thrust production, and stabilization and control of the swimming trajectory. We have used blood flow tracers in swimming rainbow trout (Oncorhynchus mykiss) to estimate the regional distribution of energy use across the myotomal and fin muscle groups to reveal the functional distribution of metabolic energy use within a swimming animal for the first time. Energy use by the myotomal muscle increased with speed to meet thrust requirements, particularly in posterior myotomes where muscle power outputs are greatest. At low speeds, there was high fin muscle energy use, consistent with active stability control. As speed increased, and fins were adducted, overall fin muscle energy use declined, except in the caudal fin muscles where active fin stiffening is required to maintain power transfer to the wake. The present data were obtained under steady-state conditions which rarely apply in natural, physical environments. This approach also has potential to reveal the mechanical factors that underlie changes in locomotor cost associated with movement through unsteady flow regimes.

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Lactate kinetics of rainbow trout during graded exercise: Do catheters affect the cost of transport?

Cited by 16 publications

References 50 publications

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Coping with an exogenous glucose overload: glucose kinetics of rainbow trout during graded swimming

Resolving Shifting Patterns of Muscle Energy Use in Swimming Fish

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