Effects of swimming training on three superoxide dismutase isoenzymes in mouse tissues

The purpose of the present study was to investigate the effects of swimming training on the changes in three superoxide dismutase (SOD) isoenzymes in mice. The trained mice underwent a 6-wk swimming program (1 h/day, 5 days/w k) in water at 35-36 degrees C. Immunoreactive extracellular SOD (EC-SOD), copper- and zinc-containing SOD (CuZn-SOD), and manganese-containing SOD (M n-SOD) contents and their mRNA abundance were determined in serum, heart, l ung, liver, kidney, and gastrocnemius muscle. EC-SOD content in liver and k idney was significantly increased with training. After training, CuZn-SOD c ontent rose significantly only in kidney but decreased significantly in hea rt, lung, and liver. Mn-SOD content showed a significant increase in lung, kidney, and skeletal muscle but a significant decrease in liver. In most ti ssues, however, the changes in SOD isoenzyme contents were not concomitant with those in their mRNA levels. The results obtained thus suggest that, ex cept for kidney, the responses in mouse tissues of three SOD isoenzymes (pr otein levels and mRNA abundance) to swimming training are different and tha t kidney may be one of the most sensitive organs to adapt to oxidative stre ss during physical training, although the mechanism remains vague.