Plasma hypoxanthine and ammonia in humans during prolonged exercise.

Document identifier: oai:dalea.du.se:2325
Publication year: 1999
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Abstract:

In this study we examined the time course of changes in the plasma concentration of oxypurines [hypoxanthine (Hx), xanthine and urate] during prolonged cycling to fatigue. Ten subjects with an estimated maximum oxygen uptake ( V?O 2max) of 54 (range 47–67) ml?·?kg -1?·?min -1 cycled at [mean?(SEM)] 74?(2)% of V?O 2max until fatigue [79?(8) min]. Plasma levels of oxypurines increased during exercise, but the magnitude and the time course varied considerably between subjects. The plasma concentration of Hx ([Hx]) was 1.3?(0.3)?µmol/l at rest and increased eight fold at fatigue. After 60?min of exercise plasma [Hx] was >10?µmol/l in four subjects, whereas in the remaining five subjects it was <5?µmol/l. The muscle contents of total adenine nucleotides (TAN?=?ATP+ADP+AMP) and inosine monophosphate (IMP) were measured before and after exercise in five subjects. Subjects with a high plasma [Hx] at fatigue also demonstrated a pronounced decrease in muscle TAN and increase in IMP. Plasma [Hx] after 60?min of exercise correlated significantly with plasma concentration of ammonia ([NH 3], r?=?0.90) and blood lactate ( r?=?0.66). Endurance, measured as time to fatigue, was inversely correlated to plasma [Hx] at 60?min ( r?=?-0.68, P?3] or blood lactate. It is concluded that during moderate-intensity exercise, plasma [Hx] increases, but to a variable extent between subjects. The present data suggest that plasma [Hx] is a marker of adenine nucleotide degradation and energetic stress during exercise. The potential use of plasma [Hx] to assess training status and to identify overtraining deserves further attention.

Authors

Kent Sahlin

Other publications >>

Michail Tonkonogi

Högskolan Dalarna; Medicinsk vetenskap
Other publications >>

Karin Söderlund

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    header: 
        identifier: oai:dalea.du.se:2325
        datestamp: 2021-04-15T12:57:29Z
        setSpec: SwePub-du
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                recordContentSource: du
                recordCreationDate: 2006-10-02
            identifier: http://urn.kb.se/resolve?urn=urn:nbn:se:du-2325
            titleInfo: 
                @attributes: 
                    lang: eng
                title: Plasma hypoxanthine and ammonia in humans during prolonged exercise.
            abstract: 
In this study we examined the time course of changes in the plasma concentration of oxypurines hypoxanthine (Hx) xanthine and urate during prolonged cycling to fatigue. Ten subjects with an estimated maximum oxygen uptake ( V?O 2max) of 54 (range 47–67) ml?·?kg -1?·?min -1 cycled at mean?(SEM) 74?(2)% of V?O 2max until fatigue 79?(8) min. Plasma levels of oxypurines increased during exercise but the magnitude and the time course varied considerably between subjects. The plasma concentration of Hx (Hx) was 1.3?(0.3)?µmol/l at rest and increased eight fold at fatigue. After 60?min of exercise plasma Hx was >10?µmol/l in four subjects whereas in the remaining five subjects it was <5?µmol/l. The muscle contents of total adenine nucleotides (TAN?=?ATP+ADP+AMP) and inosine monophosphate (IMP) were measured before and after exercise in five subjects. Subjects with a high plasma Hx at fatigue also demonstrated a pronounced decrease in muscle TAN and increase in IMP. Plasma Hx after 60?min of exercise correlated significantly with plasma concentration of ammonia (NH 3 r?=?0.90) and blood lactate ( r?=?0.66). Endurance measured as time to fatigue was inversely correlated to plasma Hx at 60?min ( r?=?-0.68 P?3 or blood lactate. It is concluded that during moderate-intensity exercise plasma Hx increases but to a variable extent between subjects. The present data suggest that plasma Hx is a marker of adenine nucleotide degradation and energetic stress during exercise. The potential use of plasma Hx to assess training status and to identify overtraining deserves further attention.

            language: 
                languageTerm: eng
            genre: 
                publication/journal-article
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                Published
                3
            name: 
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                        type: personal
                    namePart: 
                        Sahlin
                        Kent
                    role: 
                        roleTerm: aut
                    @attributes: 
                        type: personal
                        authority: du
                    namePart: 
                        Tonkonogi
                        Michail
                    role: 
                        roleTerm: aut
                    affiliation: 
                        Högskolan Dalarna
                        Medicinsk vetenskap
                    nameIdentifier: 
                        mtn
                        0000-0003-1619-9758
                    @attributes: 
                        type: personal
                    namePart: 
                        Söderlund
                        Karin
                    role: 
                        roleTerm: aut
            originInfo: 
                dateIssued: 1999
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                    type: host
                titleInfo: 
                    title: European Journal of Applied Physiology
                identifier: 
                    1439-6319
                    1439-6327
                part: 
                    detail: 
                        @attributes: 
                            type: volume
                        number: 80
                    extent: 
                        start: 417
                        end: 422
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                form: print
            typeOfResource: text