Int J Sports Med 2004; 25(5): 339-344
DOI: 10.1055/s-2004-815846
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

Sustained Swimming Increases Erythrocyte MCT1 During Erythropoiesis and Ability to Regulate pH Homeostasis in Rat

W. Aoi1 , S. Iwashita1 , M. Fujie1 , M. Suzuki1
  • 1School od Sports Sciences, Waseda University, Japan
Further Information

Publication History

Accepted after revision: September 10, 2003

Publication Date:
18 May 2004 (online)


We investigated the effect of sustained swimming exercise on the increase in monocarboxylate transporter 1 (MCT1) concentration and its ability to regulate pH homeostasis in rat erythrocytes. Male Sprague-Dawley rats aged 9 weeks were divided into sedentary and swimming groups for both 1- and 3-week experiments. The exercise group swam for 30 - 60 min/day, 5 days/week. Before and 1 and 3 weeks after initiation of the exercise, blood was collected for lactate concentration measurement during pre-exercise rest and post-exercise recovery periods. On the last day of each experiment, venous blood and erythroid cells in bone marrow were collected to assay the capacity for erythropoiesis and MCT1 concentration. In the swimming group at 0 weeks (p < 0.05), 1 week (p < 0.01) and 3 weeks (p < 0.001), the blood lactate concentration post-exercise was significantly higher than at rest. The ratio of young erythrocytes to total erythrocytes was significantly higher in the 3-week swimming group than in the sedentary group (p < 0.05). The MCT1 concentration in erythrocytes was higher in the 3-week swimming group than in the sedentary group (18 %, p < 0.05), which was found in young erythrocytes (22 %, p < 0.05) when total erythrocytes were separated into young and old fractions. The MCT1 concentration in erythroid cells was higher in both the 1-week and 3-week swimming groups than in either of the sedentary groups (27 and 28 %, respectively, p < 0.05). The pH recovery of erythrocyte suspensions at 10, 15 and 20 seconds after addition of lactate to the suspension medium was significantly faster in the 3-week swimming group than in the sedentary group (p < 0.001). These findings suggest that erythrocyte MCT1 is increased during erythropoiesis in bone marrow and that the increase of the transporter facilitates, at least partly, lactate/proton co-transport due to sustained swimming exercise in rats.


Wataru Aoi

First Department of Internal Medicine, Kyoto Prefectural University of Medicine

Kyoto 602-8566


Phone: + 81752515505

Fax: + 8 17 52 52 37 21

Email: [email protected]