Experimental Study on the Postmortem Changes of Red Blood Cells
In the present study, the author investigated the relationship between osmotic fragility changes measured using coil planet centrifuge (CPC) systems and some other factors involved in membrane resistance. The animals were killed by stabbing in the chest and blood samples were collected at varing intervals after death. In addition to morphological observation, red cells were assayed for 2,3-diphosphoglyceric acid (2, 3-DPG), potassium, magnesium and zinc. The disc-echino transformation was observed in the early postmortem period. Morphological changes were correlated well with osmotic fragility changes. The level of 2,3-DPG progressively decreased after death in quite the same manner as osmotic fragility. Among the cations, potassium and magnesium markedly decreased in the early postmortem period and were maintained at almost constant levels. Zinc decreased gradually during the period of the study. The red cells in test tube blood changed more slowly than those in postmortem cells. From these results, it can be seen that the red blood cells incubated in a carcass rapidly decrease the membrane resistance, leading to hemolysis. It is suggested that the observation of this phenomenon is of great value for estimating the postmortem period.