Acute vigorous exercise primes enhanced NO release in human platelets

Activation of platelets by acute vigorous exercise has been demonstrated by various parameters, including an increase in agonist-induced platelet [Ca2+]i levels. However, direct evidence is lacking regarding how acute exercise affects platelet-derived NO. Twenty-three healthy male non-smokers (21–59 years) underwent a symptom-limited treadmill exercise test. Washed platelets were prepared from blood samples obtained before and immediately after exercise. All subjects completed at least Bruce stage 2 and were each negative for ischemia. With a low dose (2 μg/ml) of collagen, NO release from washed platelets, detected by the NO-selective microelectrode, was significantly increased after exercise (pmols/108 platelets, before: 0.64±0.11, after: 1.03±0.18; P<0.005) without changes in aggregation ability. This enhanced NO release was accompanied by increased platelet [Ca2+]i levels (before: 232±25, after: 296±37; P<0.01). With a high dose (5 or 10 μg/ml) of collagen, NO release and aggregation were both modestly, but significantly, enhanced after exercise. The exercise-induced enhancement of platelet NO release in response to collagen was also suggested by increase in platelet cyclic guanosine monophosphate accumulation and augmenting effect of NG-monomethyl- -arginine on platelet aggregation. In summary, acute strenuous exercise primes enhanced NO release and may play a protective role against exercise-induced activation of platelets in normal subjects.