Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion
Journal Articles
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
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 [HCO3−] 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 CO2 storage responses. We conclude that an LC infusion is appropriate for studies of metabolic regulation.
