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

• Published in: Journal of applied physiology (1985) 2005-03, Vol.98 (3), p.856-865
• Main Authors: Miller, Benjamin F, Lindinger, Michael I, Fattor, Jill A, Jacobs, Kevin A, LeBlanc, Paul J, Duong, MyLinh, Heigenhauser, George J. F, Brooks, George A
• Format: Article
• Language: English
• Subjects: Acid-Base Equilibrium - physiology; Adult; Biological and medical sciences; Blood Proteins - metabolism; Carbon Dioxide - blood; Exercise; Exercise Test; Fundamental and applied biological sciences. Psychology; Hematocrit; Humans; Infusions, Intravenous; Lactic Acid - blood; Male; Men; Metabolism; Physical Endurance - physiology; Physical Exertion - physiology; Sodium; Sodium Lactate - administration & dosage; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00753.2004

1 Institute of Sports Medicine, Bispebjerg Hospital, Bispebjerg Bakke 23, Copenhagen, Denmark; 2 Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario; 4 Department of Medicine, McMaster University, Hamilton, Ontario, Canada; and 3 Department of Integrative Biology, University of California-Berkeley, Berkeley, California Submitted 19 July 2004 ; accepted in final form 6 October 2004 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% O 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 P CO 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. Stewart model; plasma volume; lactate infusion; strong ion difference; lactate transport Address for reprint requests and other correspondence: B. F. Miller, Dept. of Sport and Exercise Science, Univ. of Auckland, Tamaki Campus, Private Bag 92019, Auckland, New Zealand (E-mail: b.miller{at}auckland.ac.nz )