Influence of aging and exercise-induced stress on human platelet function

Ten healthy nonsmoking old men (age 52-70 years, OM) and ten healthy nonsmoking young men (age 20-30 years, YM) were submitted to an exercise test on a bicycle ergometer to examine the combined influence of aging and exercise-induced stress on platelet function. Data were analyzed by two-way ANOVA test to determine the statistical significance of differences between baseline, after exercise and after recovery values, and by Mann-Whitney test to compare differences between young and old groups. Our results show in OM at rest an increased platelet aggregability induced by the higher values of intraplatelet basal free calcium (143.3 +/- 4.8 vs. 121.5 +/- 6.0 nM, p < 0.05) and a statistically significant increase of plasma oxidative by-products evaluated as thiobarbituric acid-reactive substances (TBA-RS: 5.9 +/- 0.7 vs. 1.5 +/- 0.1 micromol/l, p < 0.05). Further, significant modifications of calcium and TBA-RS levels were found in both groups because of exercise-induced stress. The positive relationships between calcium amount and plasma values of TBA-RS in OM before (r = 0.728, p = 0.017) and after (r = 0.772, p = 0.009) physical test and in YM only at the end of exercise (r = 0.853, p = 0.002), underline that oxidative stress may modulate platelet function by influencing calcium homeostasis and platelet membrane permeability.