Change in composition of platelet membranes after in vitro incubation.

Platelet membranes were isolated by the glycerol lysis technique and incubated in Krebs-Ringer phosphate buffer, to determine their chemical modifications occurring during "in vitro" incubation. The main changes observed at the end of the incubation consist in a significant loss of protein components and in the nearly equimolar decrease of sialic acid and galactosamine. Aminoacid analysis indicate that mainly polar aminoacids are lost. SDS-polyacrylamide gel electrophoresis indicates that high molecular weight proteins disappear after incubation, while no relevant differences in the relative ratios between PAS-stained bands were evident. The reported modifications are quite similar to those described in the membranes of in vivo and in vitro aged red cells.