title: Opposite effects of in vitro lactate on erythrocyte deformability in athletes and untrained subjects.
abstract: Exercise transiently increases blood viscosity: however data on red cell deformability in this process remain inconsistent, since studies report either impairment (proportional to blood lactate accumulation), a lack of effect, or even in some cases an improvement. To test whether these inconsistencies may be due to physiological differences among populations studied, we compared the effects of in vitro lactate (2 mM, 4 mM and 10 mM) on erythrocyte rigidity in venous blood drawn at rest in 10 untrained vs 10 aerobically-trained subjects. After adjustment of osmolality and pH and incubation at 37 degrees C during 2 minutes, viscometric measurements were performed at 1000 s-1 with the MT90 (falling ball) viscometer and Dintenfass's 'Tk' was calculated. While at baseline there was no significant difference in Tk between the two groups, it decreased in the aerobically-trained subjects between 2 and 10 mM lactate concentrations (p<0.05) and increased in the untrained group between 2 and 4 mM (p<0.05). Thus, it seems that endurance training influences erythrocyte response to lactate. Lactate impaired erythrocyte deformability in untrained subjects but it (unexpectedly) improved it in trained subjects. This difference may be due to training-induced adaptations in erythrocyte metabolism, possibly including transmembrane transfer via monocarboxylate transporters.
authors.affiliation: UPRES EA 701 Physiologie des Interactions, Hopital Arnaud de Villeneuve, Service EFR, 34295 Montpellier cedex 5, France. pconnes@yahoo.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Connes
authors.forename: Didier
authors.initials: D
authors.lastname: Bouix
authors.forename: Guillaume
authors.initials: G
authors.lastname: Py
authors.forename: Christian
authors.initials: C
authors.lastname: Prefaut
authors.forename: Jacques
authors.initials: J
authors.lastname: Mercier
authors.forename: Jean-Frédéric
authors.initials: JF
authors.lastname: Brun
authors.forename: Corinne
authors.initials: C
authors.lastname: Caillaud
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D016022:Case-Control Studies; D004305:Dose-Response Relationship, Drug; D004907:Erythrocyte Deformability / Q000187:drug effects*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000494:pharmacology*; D010101:Oxygen Consumption; D010809:Physical Fitness; D014783:Viscosity
chemical_list: D019344:Lactic Acid