Hypoxaemia increases the accumulation of inosine monophosphate (IMP) in human skeletal muscle during submaximal exercise.
The effect of hypoxaemia on the muscle content of inosine monophosphate (IMP) during short-term, low-intensity exercise has been investigated. Six men cycled twice for 5 min at 120 +/- 6 W (mean +/- SE), which corresponded to approximately 50% of their maximal normoxic O2 uptake, breathing air (N) on one occasion and 11% O2 in N2 (H) on the other. Oxygen uptake at the end of the exercise period was similar between treatments. No significant difference was observed between H and N in the muscle metabolite contents at rest. Muscle content of phosphocreatine (PCr) decreased and lactate increased during exercise. Post-exercise PCr during H was 80% of the value during N (P greater than 0.05) and post-exercise muscle lactate was fourfold higher during H than during N (P less than 0.001). Post-exercise muscle content of ADP was significantly higher during H than during N (P less than 0.01), while ATP and AMP remained constant under both H and N exercise (P greater than 0.05 H vs N). IMP was not detectable in pre-exercise muscle samples (less than 0.01 mmol kg-1 dry wt) but increased during N exercise (0.03 +/- 0.01 mmol kg-1 dry wt, wt, P less than 0.05) and even more during H exercise (0.16 +/- 0.05 mmol kg-1 dry wt, P less than 0.05, H vs N). Post-exercise IMP was negatively related to PCr (r = -0.90) and positively related to lactate (r = 0.88). It is concluded that hypoxaemia results in an enhanced accumulation of IMP during submaximal exercise and that the IMP level is related to the degree of anaerobic energy utilization.
Department of Clinical Physiology, Karolinska Institute, Huddinge University Hospital, Sweden.
K
K
Sahlin
A
A
Katz
D000328:Adult; D015444:Exercise; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D007291:Inosine Monophosphate / Q000378:metabolism*; D007292:Inosine Nucleotides / Q000378:metabolism*; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism
D007292:Inosine Nucleotides; D010725:Phosphocreatine; D007291:Inosine Monophosphate