Malonyldialdehyde formation, oxygen consumption, fatty acid composition in newborn platelets stimulated by thrombin.

The release reaction, the formation of malonyldialdehyde (MDA), the pattern of oxygen consumption, and the variation in fatty acid composition after addition of thrombin (1.67 U/ml) have been investigated in newborn platelets, comparing the obtained data with analogous values showed by adult platelets assumed as normal controls. Newborn platelets showed a release reaction 20% lower than that of controls. MDA formation, even in the presence of NEM and the burst in oxygen consumption, resulted to be similar in newborn and adult platelets (p greater than 0.3); the burst was also similar after the addition of thrombin (10 U/ml) in the presence of antimycin and aspirin. The ratio between formed MDA and oxygen consumption was 1:10 in adult platelets while it was 1:15 in those of newborns. The study of fatty acid composition demonstrated that in newborn platelets at rest, arachidonic acid is significantly in a higher concentration than in controls and that it decreases after stimulation with thrombin. It is concluded that the pathway of prostaglandins is normally stimulated by thrombin in newborn platelets.