ANAPHYLATOXIN C5A PRODUCTION DURING SHORT-TERM SUBMAXIMAL DYNAMIC EXERCISE IN MAN

We studied the effects of short-term submaximal exercise on the plasma levels of myeloperoxidase ([MPO]) and C5a anaphylatoxin ([C5a]), take n as specific markers of polymorphonuclear neutrophil (PMN) and comple ment activation, respectively. Eleven young, healthy male volunteers w ere subjected to a constant-load concentric exercise on a cycle ergome ter (20 min at 80 % maximal oxygen uptake). Mean resting MPO and C5a c oncentrations were 437 +/- 113 and 0.47 +/- 0.21 ng/ml, respectively. During exercise, [MPG] and [C5a] increased significantly (p<0.001) tow ards respective peak values of 649 +/- 131 and 1.3 +/- 0.6 ng/ml. A ra pid decrease of both [MPO] and [C5a] was observed during recovery. The similar time course of [MPG] and [C5a] changes and the highly signifi cant relationship between these two variables (r = 0.651; p < 0.001) a rgues for the possible involvement of the complement anaphylatoxin C5a in the process of PMN degranulation. During exercise, the number of c irculating PMN increased (+ 80 %; p < 0.001) and remained practically unchanged up to 20 minutes of recovery. As [MPG] and PMN count were no t significantly related (r = 0.2; p<0.1), we concluded that the activa tion of PMN was independent of their mobilization.