Depression of plasma glutamine concentration after exercise stress and its possible influence on the immune system

Abstract

ObjectiveTo determine whether plasma glutamine levels can be used as an indicator of exercise‐induced stress, and to consider the possible effects of low plasma glutamine concentrations on the immune system. MethodsWe used two exercise regimens: in Trial 1 seven male subjects were randomly stressed on a treadmill at 0, 30%, 60%, 90% and 120% of their maximal oxygen uptake $(Vo2max); in Trial 2 five highly trained male subjects underwent intensive interval training sessions twice daily for ten days, followed by a six‐day recovery period. ResultsPlasma glutamine concentrations decreased significantly from an average of 1244+ 121 μmol/L to 702 ± 101 μmo1/L after acute exercise at 90% $VDo2max (P< 0.05) and to 560 ± 79 μmol/L at 120% $VDo2max (P< 0.001). Four of the five subjects showed reduced plasma glutamine concentrations by Day 6 of the overload training trial, with all subjects displaying significantly lower glutamine levels by Day 11. However, glutamine levels showed a variable rate of recovery over the six‐day recovery period, with two subjects' levels remaining low by Day 16. ConclusionsReduced plasma glutamine concentrations may provide a good indication of severe exercise stress.

The effects of high-intensity intermittent exercise on the plasma concentrations of glutamine and organic acids

“…These authors used a bioassay method for the assessment of glutamine (using the glutamine-dependent growth of Escherichia coli bacteria in culture), but the validity of this method can be questioned: factors other than glutamine change in blood plasma during exercise which may aect bacterial growth, thus confounding this particular method of glutamine assay. This method produces resting plasma Table 1 Heart rate (beats á min A1 ) and rating of perceived exertion (RPE) on a scale of 1 to 10 (Borg 1982) glutamine concentrations in excess of 1200 lM (Keast et al 1995;Rowbottom et al 1996) which is about double the concentrations reported using enzymatic spectrophotometric procedures (Rennie et al 1981;Lund 1985;Sewell et al 1994;Castell et al 1995). Thus, there must be some concern that their ®ndings may be an artefact of the bioassay method used to measure glutamine.…”

“…Twenty bouts of high-intensity treadmill running for 1 min separated by 2 min of recovery led to a drastic reduction in plasma glutamine concentration at 5 min post-exercise. From a mean, fasting plasma glutamine concentration of 1244 lM at rest, mean concentrations of 702 lM and 560 lM were recorded after the exercise protocol at 90% and 120% O 2max , respectively (Keast et al 1995). These authors used a bioassay method for the assessment of glutamine (using the glutamine-dependent growth of Escherichia coli bacteria in culture), but the validity of this method can be questioned: factors other than glutamine change in blood plasma during exercise which may aect bacterial growth, thus confounding this particular method of glutamine assay.…”

“…These eects may be mediated through the actions of stress hormones, cytokines and haematological factors. Falls in plasma glutamine concentration have also been implicated as a possible causal factor in immune suppression (Parry Billings et al 1990;Keast et al 1995;Rowbottom et al 1996). Most studies have reported changes in immune function following continuous prolonged exercise.…”

“…Only Keast et al (1995) have investigated the eect of interval exercise on plasma glutamine. They reported a drastic fall (»50%) in plasma glutamine at 5 min postexercise, but these authors used a bioassay method for glutamine estimation which has questionable validity.…”

Distribution of glutamine synthetase in the snapper (Pagrus auratus) and implications for the immune system

“…Blood samples were placed on ice for transfer to the laboratory where the plasma was separated by centrifugation (5 min at 1200 x g). The plasma was deproteinized and analysed for L-glutamine according to the method described by Keast et al (1995).…”