Endurance training selectively increases high-density lipoprotein-bound sphingosine-1-phosphate in the plasma.

Sphingosine-1-phosphate (S1P) is a bioactive lysosphingolipid that is found in relatively high concentration in human plasma. Erythrocytes, endothelial cells, and activated platelets are the main sources of circulating S1P. The majority of plasma S1P is transported bound to high-density lipoprotein (HDL) and albumin. In recent years, HDL-bound S1P attracted much attention due to its cardioprotective and anti-atherogenic properties. We have previously found that endurance-trained athletes are characterized by higher plasma S1P concentration compared to untrained individuals. This finding prompted us to examine the effect of endurance training on S1P metabolism in blood. Thirteen healthy, untrained, male subjects completed an 8-week training program on a rowing ergometer. Three days before the first, and 3 days after the last training session, blood samples were drawn from an antecubital vein. We found that total plasma S1P concentration was increased after the training. Further analysis of different plasma fractions showed that the training selectively elevated HDL-bound S1P. This effect was associated with activation of sphingosine kinase in erythrocytes and platelets and enhanced S1P release from red blood cells. We postulate that increase in HDL-bound S1P level is one of the mechanisms underlying beneficial effects of regular physical activity on cardiovascular diseases.

Change in blood gelsolin concentration in response to physical exercise.

Plasma gelsolin (pGSN) produced by muscle is an abundant protein of extracellular fluids capable of severing actin filaments and eliminating actin from the circulation. Additionally, pGSN modulates the cellular effects of some bioactive lipids. In this study we test the hypothesis that hormonal and metabolic adaptations to exercise are associated with changes in gelsolin concentration in blood. Plasma samples were collected from twenty healthy males recruited from untrained (UT, n=10) and endurance trained (ET, n=10) groups that performed 30-60 minutes of exercise on a cycloergometer at a workload corresponding to 70% of VO2max. Gelsolin concentration was determined by quantitative Western blot analysis with an anti-human gelsolin antibody. The gelsolin concentration in UT and ET subjects before starting exercise ranged from 104 to 330 and 163 to 337 µg · ml(-1) respectively. After 30 minutes of exercise we observed a significant decrease of plasma gelsolin in the UT group (p<0.05) while the gelsolin concentration in the ET group rose on average from 244 to 271 µg · ml(-1). However, this increase did not reach statistical significance. Endurance training might increase the ability of muscle tissue to express plasma gelsolin as part of an adaptive mechanism.

Exercise increases plasma levels of sphingoid base-1 phosphates in humans.

AIM: In recent years, blood sphingolipids attracted much attention and have been implicated in both pathophysiology and prevention of cardiovascular diseases and insulin resistance. However, factors affecting concentration and metabolism of sphingolipids in blood remain poorly recognized. We have previously found that exercise alters skeletal muscle sphingolipid metabolism. This finding prompted us to examine whether physical activity induces similar effects in blood. METHODS: Twenty healthy male patients were assigned to either untrained (UT, n = 10) or endurance trained (ET, n = 10) group. The patients performed either a 30 (UT group) or 60 (ET group) min exercise on a cycloergometer at a workload corresponding to 70% of VO(2max) . Blood samples were taken just before exercise, after 30 and 60 (ET group only) min of pedalling and following a 30-min rest. RESULTS: ET patients were characterized by higher basal plasma sphingosine-1-phosphate (S1P) concentration and decreased content of sphingosine, S1P, sphinganine-1-phosphate (SA1P) and ceramide in erythrocytes. In ET group, plasma concentrations of all measured sphingolipids remained stable both during and after exercise. On the other hand, in UT patients, the post-exercise levels of S1P and SA1P were markedly higher compared with the baseline values and this effect was accompanied by decreased erythrocyte ceramide content. CONCLUSION: It is likely that single bout of exercise and endurance training enhances production and release of S1P by erythrocytes. We speculate that exercise-induced increase in plasma S1P concentration might be one of the mechanisms underlying beneficial effects of physical activity on cardiovascular health and insulin sensitivity.