Comparative studies of the isozymes of lactic dehydrogenase in rabbit and man. Observations during development and in tissue culture.

During development of rabbit tissues, characteristic sequential alterations in the LDH isozyme pattern occur, and consist for liver and muscle in loss of the most rapidly migrating anodal bands, and increased activity in the cathodal bands and slower migrating anodal bands. In heart the reverse changes were observed. Comparison of the isozyme patterns observed in various fetal and adult human tissues suggests that these same sequential alterations probably occur. A species-specific isozyme pattern is obtained in long term culture of rabbit, chick, and human cells. The alterations in tissue culture are characterized by a gradual redistribution of total LDH activity in which there is decreased intensity of rapidly migrating anodal bands. These sequential alterations are independent of the organ of origin. The number of bands observed in the starch gel is partly dependent upon the total activities applied. Isozymes may provide a convenient method for determining the species of origin of cell lines in common use and for investigating the effects of various alterations in the in vitro environment on cells grown in tissue culture.