Malondialdehyde Formation Induced By Different Collagens

To get close information about the characteristics of collagen induced MDA formation, platelet aggregation was induced by collagen type I, III a. V in dissolved and fibrillar form and by methylated type I collagen. The MDA formation was measured in the course of aggregation. In case of Meth.c. MDA production is induced also if under certain incubation conditions no aggregation is detectible.During the pl.aggr. induced by dissolved c. some MDA production was seen before the slope of the aggregation curve increased. Parallel to the increasing slope MDA increased fast, and some further increase over a 30 min. period was observed. For fibrillar and meth.c. MDA formation begins just with the increasing slope and reaches a stable plateau. In case of meth.c. the plateau is reached immediately after the maximum of aggregation occurred, in that of fibrillar c. some min. after maximal aggregation. For meth.c. the results obtained in the incubation system were comparable to that in the aggregation system.For meth.c. the kinetics of MDA formation in both systems were further defined. In both systems a concentration dependent saturation kinetic was obtained. In the aggregation system the concentration dependent increase of MDA formation was somewhat faster as in the incubation system and reached its saturation level at a lower collagen concentration.From the increasing and long lasting MDA formation induced by the interstitial collagens we might speculate that in vivo the stimulating activity of the collagens may work for a long time in conditions where the prostacyclin production of the vessel wall is decreased. The characteristics of MDA formation induced by meth.c. suggest that this c. may be a good tool for in vitro studies.