ABSTRACT
The aim of the present study was to examine the effects of 8 weeks of exercise training on the fatty acid composition of phospholipids (PL) and triacylglycerols (TG) in rat liver, skeletal muscle (gastrocnemius medialis), and adipose tissue (epididymal and subcutaneous fat). For this purpose, the relevant tissues of 11 trained rats were compared to those of 14 untrained ones. Training caused several significant differences of large effect size in the concentrations and percentages of individual fatty acids in the aforementioned lipid classes. The fatty acid composition of liver PL, in terms of both concentrations and percentages, changed with training. The TG content of muscle and subcutaneous adipose tissue decreased significantly with training. In contrast to the liver, where no significant differences in the fatty acid profile of TG were found, muscle underwent more significant differences in TG than PL, and adipose tissue only in TG. Most differences were in the same direction in muscle and adipose tissue TG, suggesting a common underlying mechanism. Estimated fatty acid elongase activity was significantly higher, whereas Delta(9)-desaturase activity was significantly lower in muscle and adipose tissue of the trained rats. In conclusion, exercise training modified the fatty acid composition of liver PL, muscle PL and TG, as well as adipose tissue TG. These findings may aid in delineating the effects of exercise on biological functions such as membrane properties, cell signaling, and gene expression.
Subject(s)
Adipose Tissue/physiology , Fatty Acids/metabolism , Liver/physiology , Muscle, Skeletal/physiology , Phospholipids/metabolism , Physical Conditioning, Animal/methods , Physical Exertion/physiology , Triglycerides/metabolism , Adaptation, Physiological/physiology , Animals , Lipid Metabolism , Lipids/classification , Male , Muscle Contraction/physiology , Organ Specificity , Rats , Rats, WistarABSTRACT
BACKGROUND: Endothelin, a natural peptide exhibiting potent vasoconstrictor activity, may play a crucial role in cardiovascular disease. The purpose of the present study was to compare the effect of an aerobic exercise bout on plasma ET levels in trained and untrained subjects. MATERIAL/METHODS: Nine healthy physically active males and nine sedentary controls cycled at 60% of their maximal aerobic power for 30 min. Plasma endothelin was determined by enzyme immunoassay at rest and 30 min after the end of the exercise. Endothelin values were compared through two-way (training status x time) analysis of variance with repeated measures on time. Changes in plasma volume, calculated from hematocrit and hemoglobin data, were compared through independent Student's t test. RESULTS: We found a significant interaction of training status and time (p=0.05) resulting from opposite changes in the trained and untrained group (decrease in the former from 4.3+/-1.1 to 2.0+/-0.6 pg/ml vs. increase in the latter from 2.6+/-0.6 to 3.3+/-1.1 pg/ml). Changes in plasma volume with exercise were significantly different (decrease in the trained group vs. increase in the untrained group, p=0.03). CONCLUSIONS: Our data indicate that aerobic training may reverse the augmentative effect of acute exercise on plasma endothelin levels. This adaptation may represent a novel beneficial effect of regular physical activity on human health.
