title: Effect of prolonged physical exercise on intra-erythrocyte and plasma potassium.
abstract: The intracellular concentrations of sodium [Na+] and potassium [K+] and the water content in human erythrocytes were investigated in 21 male runners before and after a marathon. From 2 to 5 min after the race, the intra-erythrocyte [K+] was significantly decreased (p less than 0.001) by 7% whereas the plasma [K+], intra-erythrocyte [Na+] and the erythrocyte water content were unchanged. The change in the intra-erythrocyte [K+] observed immediately after the marathon, was negatively correlated with the race time (r = -0.44; p less than 0.05). Furthermore, the change in the plasma [K+] (r = -0.64; p less than 0.001) and the amount of K+ excreted in the urine during the race (r = 0.54; p less than 0.05) were also, respectively, negatively and positively correlated with the race time. It is concluded that during prolonged physical exercise the erythrocytes could serve as a kind of K+ reservoir that is drained with increasing magnitude of body K+ loss. This might explain why in the faster marathon runners, in whom the urinary K+ loss is smaller and the K+ intake is greater than in the slower runners during race, the intra-erythrocyte [K+] is unchanged after a marathon whereas in the slower runners it is decreased.
authors.affiliation: Department of Pathophysiology, University of Leuven, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Lijnen
authors.forename: P
authors.initials: P
authors.lastname: Hespel
authors.forename: R
authors.initials: R
authors.lastname: Fagard
authors.forename: M
authors.initials: M
authors.lastname: Goris
authors.forename: R
authors.initials: R
authors.lastname: Lysens
authors.forename: E
authors.initials: E
authors.lastname: Vanden Eynde
authors.forename: A
authors.initials: A
authors.lastname: Amery
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood; D000704:Analysis of Variance; D001798:Blood Proteins / Q000032:analysis; D003404:Creatinine / Q000097:blood / Q000652:urine; D004326:Drinking; D004912:Erythrocytes / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D011188:Potassium / Q000097:blood*; D012044:Regression Analysis; D012420:Running; D012964:Sodium / Q000097:blood / Q000652:urine
chemical_list: D001798:Blood Proteins; D006454:Hemoglobins; D007328:Insulin; D007773:Lactates; D000450:Aldosterone; D012964:Sodium; D003404:Creatinine; D011188:Potassium