Effects of acute moderate exercise on the phagocytosis of Kupffer cells in rats

Aim: This study investigated the function of Kupffer cells, and particularly their role as immunocompetent cells that come into contact with gut-derived endotoxin, in the acute exercise of rats. Methods: Female Fischer 344 rats were run on a treadmill at 21 m min(-1) for 60 min on a 15% grade. Results: Afterwards, the number of latex particles in the liver was higher in the exercising rats than that in resting rats and an increase in the number of latex particles phagocytosed by each Kupffer cell was noted. The plasma endotoxin concentration was significantly higher in the exercise group than in the resting rats, and the small intestine was damaged by the exercise. Plasma corticosterone and thyroxine 4 levels were unchanged. Although the number of Kupffer cells was unchanged by acute exercise, the number of CD14-positive Kupffer cells increased. Plasma liver enzyme activities were slightly increased by acute exercise, whereas plasma tumour necrosis factor-alpha was not detected. Conclusion: These results suggest that moderately intense exercise increases the phagocytosis of Kupffer cells, and that it might be induced by endotoxemia of portal blood caused by intestinal mucosal lesions resulting from acute exercise.