Alterations caused by physical training in pulmonary edema and loss of muscle mass in rats with Walker-256 tumor Altera es promovidas pelo treinamento físico no edema pulmonar e perda de massa muscular em ratos portadores de tumor Walker-256

Walker-256 tumor is a fast-growing tumor and has been studied under several metabolic aspects associated or not to cachexia. It was observed in our laboratory that animals with Walker-256 tumor, after spontaneous death (usually around the fifteenth day), showed significant pulmonary edema with fluid in the pleural cavity. Some studies have suggested that physical training improves the survival of animals with tumor and minimizes the effects of cachexia. The purpose of our work was to assess the pulmonary edema index as well as the cardiac and skeletal muscle mass, besides the survival of rats with Walker-256 tumor submitted previously to physical training through swimming (N). For this study male Wistar rats (200 to 220 g) were used, submitted to physical training through swimming (1 hour; 5 days a week, four weeks). One day after the training, sedentary rats (C) or trained ones (N) were submitted to inoculation on the right flank of 8 x 107 Walker-256 tumor cells (T). Immediately after spontaneous death of these animals, the pulmonary edema index (PEI), cardiac and skeletal muscle mass (gastrocnemius and soleus) were evaluated. Pulmonary edema was evaluated through the index calculated by the relation between lung and body weights of each animal, and multiplied by 100 (PP/PC x 100) (LEE et al., 2001). Muscle mass (MM) index was calculated similarly. In normal animals the PEI is equal to 0,53±0,02 (n=20). In tumor-bearing rats after spontaneous death the PEI was significantly higher (2,62±0,31, n=18). After the physical training in rats without tumor, the PEI was 0,55±0,03 (n=5). Whereas in tumor-bearing rats previously trained, it was obtained a pulmonary edema index lower than that of the control group with tumor (1,46±0,16, n=5; p<0,05). In terms of muscle mass, it was verified, as expected, a reduction in the gastrocnemius muscle mass index in the control group with tumor when compared to the group without tumor (C=0,53±0,01; CT=0,38±0,02). The same thing happened for the soleus muscle (C=0,11±0,01; CT=0,08±0,01). The physical training did not modify the MMI of all the muscles evaluated when compared to the control group without tumor. However, in the trained rat with tumor, the MMI of the gastrocnemius muscle was higher when compared to the control group with tumor (CT=0,38±0,02; NT=0,46±0,02, p<0,05). In terms of the cardiac muscle, the physical training did not alter the cardiac mass index, but the presence of the tumor caused in both groups (C and N) a hypertrophy. Our results show that the pulmonary edema is present in animals with Walker-256 tu