Document Detail

Changes in arterial, mixed venous and intraerythrocytic ion concentrations during prolonged exercise.
MedLine Citation:
PMID:  21059004     Owner:  NLM     Status:  MEDLINE    
REASONS FOR PERFORMING STUDY: Prolonged equine exercise can cause hypochloraemic alkalosis and hypokalaemia secondary to the loss of hypertonic sweat. Movement of ions in and out of erythrocytes during exercise may help regulate acid-base balance and changes in plasma ion concentrations. The extent to which this happens during prolonged equine exercise has not been reported.
OBJECTIVES: To measure changes in blood gases and major plasma and intraerythrocytic (iRBC) ion concentrations of horses undergoing prolonged submaximal exercise.
METHODS: Six horses were trotted at ∼ 30% VO2max on a treadmill for 105 min. Arterial ((a)) and mixed venous ((v)) blood samples were collected every 15 min, and pre- and post exercise. Blood gases and plasma (pl) concentrations of sodium, potassium, chloride and protein were measured and their iRBC concentrations calculated and compared (P < 0.05).
RESULTS: P(a)CO(2) decreased in all horses. pl[Cl(-)]v decreased and [HCO(3)(-)]v increased. Due to the exhalation of CO(2) and chloride shifting, [HCO(3)(-)]a<[HCO(3)(-)]v, pl[Cl(-)]a>pl[Cl(-)]v)and iRBC[Cl(-)]a<iRBC[Cl(-)]v. pl[K(+)]a and pl[K(+)](v) both initially increased then decreased and horses were hypokalaemic post exercise. Both iRBC[Cl(-)](a) and iRBC[Cl(-)](v) decreased over the course of exercise but there was no change in the arteriovenous difference between them. There was no arteriovenous difference in pl[K(+)]. iRBC[K (+)]a>iRBC[K(+)]v. Conversely, iRBC[Na(+)]a<iRBC[Na(+)]v). pl[Na(+)]a<pl[Na(+)]v and [TP]a<[TP]v.
CONCLUSIONS: Significant arteriovenous differences in iRBC and plasma concentrations of chloride, potassium and sodium reflect the role that movement of ions across erythrocyte cell membranes play in regulating acid-base balance and plasma concentrations of these ions. Exhalation of CO(2) has a major influence on this ion flux.
N D Meyer; W M Bayly; R H Sides; K J Wardrop; B K Slinker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Equine veterinary journal. Supplement     Volume:  -     ISSN:  -     ISO Abbreviation:  Equine Vet J Suppl     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-09     Completed Date:  2011-08-17     Revised Date:  2012-06-13    
Medline Journal Info:
Nlm Unique ID:  9614088     Medline TA:  Equine Vet J Suppl     Country:  England    
Other Details:
Languages:  eng     Pagination:  185-90     Citation Subset:  IM    
Copyright Information:
© 2010 EVJ Ltd.
College of Veterinary Medicine, Washington State University, Washington, USA.
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MeSH Terms
Blood Gas Analysis / veterinary
Body Temperature / physiology
Erythrocytes / metabolism*
Exercise Test
Hydrogen-Ion Concentration
Ions / blood*,  metabolism*
Physical Conditioning, Animal / physiology*
Physical Exertion
Time Factors
Reg. No./Substance:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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