Abstract

We studied the effects of short-term submaximal exercise on the plasma levels of myeloperoxidase (<MPO>) and C5a anaphylatoxin (<5a>), taken as specific markers of polymorphonuclear neutrophil (PMN) and complement activation, respectively. Eleven young, healthy male volunteers were subjected to a constant-load concentric exercise on a cycle ergometer (20 min at 80 maximal oxygen uptake). Mean resting MPO and C5a concentrations were 437+/-113 and 0.47+/-0.21 ng/ml, respectively. During exercise, <MPO> and <C5a> increased significantly (p<0.001) towards respective peak values of 649+/-131 and 1.3+/-0.6 ng/ml. A rapid decrease of both <MPO> and <C5a> was observed during recovery. The similar time course of <MPO> and <C5a> changes and the highly significant relationship between these two variables (r=0.651; p<0.001) argues for the possible involvement of the complement anaphylatoxin C5a in the process of PMN degranulation. During exercise, the number of circulating PMN increased (+80; p<0.001) and remained practically unchanged up to 20 minutes of recovery. As <MPO> and PMN count were not significantly related (r=0.2; p<0.1), we concluded that the activation of PMN was independent of their mobilization. Verf.-Referat