Plasma endothelin-1 level in athletes after exercise in a hot environment: exercise-induced dehydration contributes to increases in plasma endothelin-1.

We investigated whether dehydration due to exercise contributes to the increase in plasma endothelin-1 (ET-1) concentration. We measured the plasma concentration of ET-1 before and after exercise in a hot environment (about 30 degrees C). Five male intercollegiate Kendo (Japanese fencing) players entered the present study. Each athlete participated in 15 min of Kendo fighting, followed by 5 min of rest and another 15 min of Kendo fighting (i.e., total exercise 30 min), with or without oral intake of 700 ml of water. Body weight and left atrial diameter, a parameter that reflects changes in circulating plasma volume, were significantly decreased after exercise under both conditions. However, the decreases in both values were significantly greater after exercise without water intake than after exercise with water intake, indicating that dehydration and decreased circulating plasma volume were more marked after exercise without water intake. The extent of the increase in plasma ET-1 concentration appeared to be closely related to the extent of exercise-induced dehydration; the greater the dehydration, the greater the increase in plasma ET-1 concentration. These findings suggest that exercise-induced dehydration may contribute to increases in plasma ET-1 concentrations.