Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion

Benjamin F. Miller, Michael I. Lindinger, Jill A. Fattor, Kevin A. Jacobs, Paul J. LeBlanc, Mylinh Duong, George J.F. Heigenhauser, George A. Brooks

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


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% V̇O2 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 [HCO3 -]. A decrease in plasma total weak acid concentration also contributed to these changes, whereas PCO2 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.

Original languageEnglish (US)
Pages (from-to)856-865
Number of pages10
JournalJournal of applied physiology
Issue number3
StatePublished - Mar 2005
Externally publishedYes


  • Lactate infusion
  • Lactate transport
  • Plasma volume
  • Stewart model
  • Strong ion difference

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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