Document Detail


K+ balance in humans during exercise.
MedLine Citation:
PMID:  8729688     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Onset of exercise leads to a sudden increase in [K+] in venous plasma from the exercising muscles. Delayed by about 10 s. the arterial [K+] rises nearly at the same rate as the venous concentration. At exercise intensities below 100% of Vo2max, both venous and arterial [K+] stabilize at a steady-state value. At higher intensities, venous and arterial plasma [K+] continue to rise until exhaustion. During the first 5 min of exercise the contracting muscles always lose K+, with a peak in loss rate after 1-2 min. During steady state, the loss rate is minimized or may even be reduced to zero. The loss is caused by an exercise-induced afflux of K+ from the contracting cells which exceeds the exercise-induced influx mediated by the Na, K pump. The Na, K pump is stimulated by catecholamines in vitro and in resting tissue in vivo. However, the loss rate of K+ from steady-state exercising muscles does not show any increase during beta -adrenergic blockade or decrease during beta-adrenergic stimulation. This is probably due to a compensatory change in intracellular [Na+]. During low exercise intensity, arterial [K+] does not increase after 1-2 min. while the exercising muscles lose K+, showing that the extracellular pool of K+ is redistributed. During beta-adrenergic blockade this redistribution is impaired so that the rise in plasma [K+] is accentuated. Conversely alpha-adrenergic blockade reduces the exercise-induced hyperkalaemia. Hence, the adrenergic system plays an important role in regulation of whole-body K+ balance during exercise but its significance in exercising muscles is not clear.
Authors:
J Hallén
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  156     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  1996 Mar 
Date Detail:
Created Date:  1996-10-23     Completed Date:  1996-10-23     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  279-86     Citation Subset:  IM; S    
Affiliation:
Norwegian University of Sport and Physical Education, Oslo, Norway.
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MeSH Terms
Descriptor/Qualifier:
Exercise / physiology*
Humans
Muscle, Skeletal / metabolism,  physiology
Potassium / blood,  metabolism*
Chemical
Reg. No./Substance:
7440-09-7/Potassium

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