A quantitative assessment of circulating progenitor cells in competitive athletes and in sedentary subjects.

AIM: Hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs) are known to play a role in the vascular responses and adaptations to exercise. We performed a quantitative assessment of HSCs and EPCs in adolescents in order to investigate whether resting levels of circulating HSCs and EPCs are comparable between elite athletes and sedentary healthy subjects. METHODS: HSCs and EPCs levels were measured in adolescent competitive football players and in age- and sex-matched sedentary controls. A laboratory testing was also performed to determine the white blood cells count and the lipid profile. All athletes were evaluated at the same stage of their training program, after 6 months of training. Controls were not engaged in any kind of routine training program. RESULTS: Twenty male competitive athletes (18.4 ± 0.5 years) and 9 sedentary controls (18.7 ± 0.4 years) participated in the study. As expected, HDL cholesterol was higher in athletes as compared with controls (P<0.05). No significant differences in the other laboratory parameters were observed among groups. Circulating levels of HSCs were significantly lower in athletes in comparison with sedentary controls (P<0.05). Conversely, EPCs and KDR+ cell subpopulations did not substantially differ between athletes and controls. CONCLUSION: Adolescent athletes exhibit lower levels of circulating HSCs but not of EPCs compared to sedentary controls. The process of tissue repair associated with intensive training can contribute to this difference, acting as a stimulus for mobilization and homing of HSCs in the site of injuries.

Effects of 50 Hz electromagnetic fields on rat cortical synaptosomes.

Nerve cells are very responsive to weak pulsed electromagnetic fields (EMFs). Such non-ionizing radiation, with frequencies of 0-300 Hz and 0.1-100 mT, can affect several cellular activities, with unusual dose-response characteristics. The present study examined the effect of a 2-h exposure of synaptosomes on a system generating a peak magnetic field of 2 mT. We evaluated the changes of the synaptosomal mitochondrial respiration rate and ATP production, membrane potential, intrasynaptosomal Ca2+ concentration, and the release of free iron and F2-isoprostanes. O2 consumption and ATP production remained unchanged in exposed synaptosomes. The intrasynaptosomal Ca2+ concentration decreased slowly and no depolarization of the synaptosomal membrane was detected. Finally, the release of free iron and F2-isoprostanes by synaptosomal suspensions also remained unchanged after EMF exposure. These results indicate that the physiological behavior of cortical synaptosomes was unaffected by weak pulsed EMFs.

Physiopathological effects of the NO donor 3-morpholinosydnonimine on rat cortical synaptosomes.

The NO donor 3-Morpholinosydnonimine (SIN-1) releases NO in the presence of molecular oxygen. In this study, we evaluated the effect of SIN-1 on mitochondria of rat cortical synaptosomes. We demonstrated in vitro that the amount of ONOO(-) generated and H(2)O(2) formation directly correlated with SIN-1 concentration. The mean oxygen consumption by synaptosomal mitochondria was approximately 3.8 nmol of O(2) min(-1) mg(-1) protein, which decreased significantly in the presence of SIN-1 1 mM to 2.5 nmol O(2) min(-1) mg(-1). This decrease was not modified by catalase or Trolox, demonstrating that ONOO(-) was responsible for the effect. The same concentration of SIN-1 caused a significant decrease of ATP production by synaptosomal mitochondria and depolarized the mitochondrial membrane. Moreover, ROS production increased progressively and was completely inhibited by pre-incubation of synaptosomes with Trolox. Finally, phosphatidylserine was externalized and, at the same time, intrasynaptosomal lactate dehydrogenase decreased confirming both, the external membrane breakdown after the addition of SIN-1 and the damage to the synaptosomes.

Synaptosome behaviour is unaffected by weak pulsed electromagnetic fields.

The present study examined the effect on rat cortical synaptosomes of a 2 h exposure to 50-Hz electromagnetic fields (EMFs) with a peak magnetic field of 2 mT. We measured modifications of synaptosomal mitochondrial respiration rate, ATP production, membrane potential, intrasynaptosomal Ca(2+) concentration and free iron release. The O(2) consumption remained unvaried in exposed synaptosomes at about 2 nM O(2)/min/mg proteins; ATP production was also unchanged. The intrasynaptosomal Ca(2+) concentration decreased slowly and there was a slight, but non-significant, depolarisation of the synaptosomal membrane. Finally, the free iron release by synaptosomal suspensions, a useful predictor of neuro-developmental outcome, remained unchanged after EMF exposure. On the whole, our results indicate that the physiological behaviour of cortical synaptosomes is not affected by weak pulsed EMFs.