| Purposes. Studies were proposed to further determine effects of long-term exercise on iron metabolism in animal model and their regulatory mechanisms.;Methods. Swimming exercise was performed on rats to investigate: (1) effects of long-term swimming exercise on iron status; (2) changes in cellular iron uptake; (3) role of nitric oxide (NO) in exercise-induced low iron status.;Results. The main findings are: (1) Long-term swimming led to a low iron status presented by decreased transport iron and storage iron in the liver, spleen, heart, kidney, and bone marrow cells; (2) Exercise increased expression of erythroblast transferrin (Tf) receptor (TfR) without change in TfR affinity, and enhanced TfR-mediated iron uptake; (3) The increase of TfR and TfR-mediated iron uptake, and the decrease of plasma iron and Tf iron saturation were similar amongst exercise groups. Prolonged exercise did not develop a true "sport anemia". (4) The maximal rates and Michaelis constants of Fe(II) uptake in bone barrow cells were affected by 6-month exercise; (5) Exercise decreased cytosolic aconitase activity in the liver, spleen, and bone marrow cells, indicating that exercise may genetically affect expression of iron binding protein; (6) Exercise increased NO products in plasma, liver, spleen and bone marrow cells. Plasma NO concentration correlated plasma iron concentration in exercise groups. Above additional NO production were blocked by NO synthase inhibitor, L-NAME, and iron storage was partly restored by L-NAME; (7) The decreased cytosolic aconitase activity with exercise could be intervened by L-NAME, in the liver, spleen and bone marrow cells NO might genetically regulate iron metabolism with exercise.;Conclusions. Results in this thesis support that exercise may lead to a low iron status. Such a low iron status is similar to, but in part different from, that caused by a nutritional iron deficiency, since exercise-induced low iron status does not develop to anemia stage. Such a low iron status is similar to, but different from, that associated with chronic diseases, since NO involves iron retention in RE cells in chronic diseases. A new NO hypothesis was presented that NO might be one factor through which exercise induces low iron status dissimilar to iron deficiency. |
