Contribution of erythrocytes to the control of the electrolyte changes of exercise.
Five healthy males performed four 30-s bouts of maximal isokinetic cycling with 4 min rest between each bout. Arterial and femoral venous blood was sampled during and for 90 min following exercise. During exercise, arterial erythrocyte [K+] increased from 117.0 +/- 6.6 mequiv./L at rest to 124.2 +/- 5.9 mequiv./L after the second exercise bout. Arterial erythrocyte [K+] returned to the resting values during the first 5 min of recovery. No significant change was observed in femoral venous erythrocyte [K+]. Arterial erythrocyte lactate concentration ([Lac-]) increased during exercise from 0.2 +/- 0.1 mequiv./L peaking at 9.5 +/- 1.5 mequiv./L at 5 min of recovery, after which the values returned to control. Femoral venous erythrocyte [Lac-] changed in a similar fashion. Arterial erythrocyte [Cl-] rose during exercise to 76 +/- 3 mequiv./L and returned to resting values (70 +/- 2 mequiv./L) by 25 min recovery. During exercise there was a net flux of Cl- into the erythrocyte. We conclude that erythrocytes are a sink for K+ ions leaving working muscles. Furthermore, erythrocytes function to transport Lac- from working muscle and reduce plasma acidosis by uptake of Cl-. The erythrocyte uptake of K+, Lac-, and Cl- helps to maintain a concentration difference between plasma and muscle, facilitating diffusion of Lac- and K+ from the interstitial space into femoral venous plasma.
McKelvie
R S
RS
Ambrose Cardiorespiratory Unit, McMaster University Health Sciences Centre, Hamilton, Ont., Canada.
Lindinger
M I
MI
Heigenhauser
G J
GJ
Jones
N L
NL
D000136:Acid-Base Equilibrium / Q000502:physiology; D000138:Acidosis / Q000097:blood; D000328:Adult; D002712:Chlorides / Q000097:blood; D004573:Electrolytes / Q000097:blood*; D004912:Erythrocytes / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006400:Hematocrit; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood
D002712:Chlorides; D004573:Electrolytes; D007773:Lactates; D012964:Sodium; D011188:Potassium