Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion.
An emerging technique used for the study of metabolic regulation is the elevation of lactate concentration with a sodium-lactate infusion, the lactate clamp (LC). However, hematological and acid-base properties affected by the infusion of hypertonic solutions containing the osmotically active strong ions sodium (Na(+)) and lactate (Lac(-)) are a concern for clinical and research applications of LC. In the present study, we characterized the hematological and plasma acid-base changes during rest and prolonged, light- to moderate-intensity (55% Vo(2 peak)) exercise with and without LC. During the control (Con) trial, subjects were administered an isotonic, isovolumetric saline infusion. During LC, plasma lactate concentration ([Lac(-)]) was elevated to 4 meq/l during rest and to 4-7 meq/l during exercise. During LC at rest, there were rapid and transient changes in plasma, erythrocyte, and blood volumes. LC resulted in decreased plasma [H(+)] (from 39.6 to 29.6 neq/l) at the end of exercise while plasma [HCO(3)(-)] increased from 26 to 32.9 meq/l. Increased plasma strong ion difference [SID], due to increased [Na(+)], was the primary contributor to decreased [H(+)] and increased [HCO(3)(-)]. A decrease in plasma total weak acid concentration also contributed to these changes, whereas Pco(2) contributed little. The infusion of hypertonic LC caused only minor volume, acid-base, and CO(2) storage responses. We conclude that an LC infusion is appropriate for studies of metabolic regulation.
Institute of Sports Medicine, Bispebjerg Hospital, Bispeberg Bakke 23, Copenhagen, Denmark. b.miller@auckland.ac.nz
Benjamin F
BF
Miller
Michael I
MI
Lindinger
Jill A
JA
Fattor
Kevin A
KA
Jacobs
Paul J
PJ
Leblanc
Mylinh
M
Duong
George J F
GJ
Heigenhauser
George A
GA
Brooks
D000136:Acid-Base Equilibrium / Q000502:physiology*; D000328:Adult; D001798:Blood Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood*; D005080:Exercise Test; D006400:Hematocrit; D006801:Humans; D007262:Infusions, Intravenous; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D019354:Sodium Lactate / Q000008:administration & dosage*
D001798:Blood Proteins; D002245:Carbon Dioxide; D019344:Lactic Acid; D019354:Sodium Lactate