Submitted on June 29, 2005
Accepted on October 4, 2005
FASTER LACTATE TRANSPORT ACROSS RED BLOOD CELL MEMBRANE IN SICKLE CELL TRAIT CARRIERS
Sara Fagnete1, Connes Philippe2, Hue Olivier2*, Montout-Hedreville Mona3, Etienne-Julan Maryse4, and Hardy-Dessources Marie-Dominique5
1 UFR STAPS, Universite des Antilles et de la Guyane Campus de Fouillole, ACTES UPRES-EA 3596 Laboratory, 97159 Pointe-a- Pitre Cedex, Guadeloupe; Centre Hospitalier Universitaire, UMR S 458 Inserm- Universite des Antilles et de la Guyane, Pointe-a-Pitre, Guadeloupe
2 UFR STAPS, Universite des Antilles et de la Guyane Campus de Fouillole, ACTES UPRES-EA 3596 Laboratory, 97159 Pointe-a- Pitre Cedex, Guadeloupe
3 Centre Hospitalier Universitaire, Service de Cardiologie, Pointe-a-Pitre, Guadeloupe
4 Centre Hospitalier Universitaire, UMR S 458 Inserm- Universite des Antilles et de la Guyane, Pointe-a-Pitre, Guadeloupe; Centre Hospitalier Universitaire, Centre Caribeen de la Drepanocytose Guy Merault, Pointe-a-Pitre, Guadeloupe
5 Centre Hospitalier Universitaire, UMR S 458 Inserm- Universite des Antilles et de la Guyane, Pointe-a-Pitre, Guadeloupe
* To whom correspondence should be addressed. E-mail: HueO{at}wanadoo.fr.
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 haemoglobin (AA). Sixteen Caribbean students, nine AS and seven AA, performed a progressive and maximal exercise test to determine the maximal oxygen consumption (VO2 max). Blood samples were obtained at rest to assess haematological parameters and RBC lactate transport activity. Lactate influxes (total lactate influx and MCT-1-mediated lactate influx) into erythrocytes were measured at four external labelled [14C] lactate concentrations (1.6, 8.1, 41 and 81.1 mM). The two groups had similar VO2 max. 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 (Vmax) 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 individuals with normal haemoglobin. The higher MCT-1 Vmax found in AS suggests greater content or greater activity of MCT-1 in AS red blood cell membranes.
