Preservation of the Lactic Dehydrogenase Activity of Platelets by Freezing in Dimethylsulfoxide and Plasma.

MEDIUM composed of 15 per cent dimethylsulfoxide ( DMSO ) in a 50 per cent solution of plasma has previously been reported to preserve the clot-retracting activity of frozen human platelets stored under liquid nitrogen at -175 C.’ In order to study further the maintenance of platelet “viability” by this technic, the activity of lactic dehydrogenase ( LDH ) was examined before and after freezing. Lactic acid dehydrogenase was chosen as a representative platelet enzyme because it plays a crucial role in the glycolytic metabolism. Maupin2 and Gross3 have shown that platelets contain considerable amounts of glycogen and have an active anaerobic glycolytic metabolism. As demonstrated by Campbell and his associates,4’5 the activity of platelet lactic acid dehydrogenase is closely related to the rate of glucose consumption. Furthermore, the LDH activity parallels clot retracting activity4 and is lost rapidly when platelets are lysed chemically or mechanically.6