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Faster lactate transport across red blood cell membrane in sickle cell trait carriers

¹Laboratoire Adaptation au Climat Tropical, Exercice et Société Unité Propre de Recherche de l’Enseignment Supérieur–Equipe d’Accueil 3596, Unité de Formation et de Recherche Sciences et Technique des Activités Physiques et Sportíves, Université des Antilles et de la Guyane, Campus de Fouillole, Pointe-à- Pitre Cedex; ²Unité Mixte de Recherche en Santé 458 Inserm-Université des Antilles et de la Guyane, Centre Hospitalier Universitaire Pointe-à-Pitre; ³Centre Caribéen de la Drépanocytose "Guy Mérault," Centre Hospitalier Universitaire Pointe-à-Pitre; and ⁴Service de Cardiologie, Centre Hospitalier Universitaire Pointe-à-Pitre, Guadeloupe

Submitted 28 June 2005 ; accepted in final form 4 October 2005

The physical and physiological behavior of sickle cell trait carriers (AS) is somewhat equivocal under strenuous conditions, although this genetic abnormality is generally considered to be a benign disorder. The occurrence of incidents and severe injuries in AS during exercise might be explained, in part, by the lactic acidosis due to a greater lactate influx into AS red blood cells (RBCs). In the present study, the RBC lactate transport activity via the different pathways was compared between AS and individuals with normal hemoglobin (AA). Sixteen Caribbean students, nine AS and seven AA, performed a progressive and maximal exercise test to determine maximal oxygen consumption. Blood samples were obtained at rest to assess haematological parameters and RBC lactate transport activity. Lactate influxes [total lactate influx and monocarboxylate transporter (MCT-1)-mediated lactate influx] into erythrocytes were measured at four external [¹⁴C]-labeled lactate concentrations (1.6, 8.1, 41, and 81.1 mM). The two groups had similar maximal oxygen consumption. Total lactate influx and lactate influx via the MCT-1 pathway were significantly higher in AS compared with AA at 1.6, 41, and 81.1 mM. The maximal lactate transport capacity for MCT-1 was higher in AS than in AA. Although AS and AA had the same maximal aerobic physical fitness, the RBCs from the sickle cell trait carriers took up more lactate at low and high concentrations than the RBCs from AA individuals. The higher MCT-1 maximal lactate transport capacity found in AS suggests greater content or greater activity of MCT-1 in AS RBC membranes.

lactate influx; monocarboxylate transporter; hemoglobin S; lactate transport capacity

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CORRIGENDUM

Journal of Applied Physiology 2006 101: 372. [Full Text]