Intracellular enzymes in local lymph as a measure of cellular injury.

1. Lymph was collected directly from the hind limb of cats anaesthetized with pentobarbitone before and for several hours after the limb was injured.2. After the limb was subjected to very mild injury such as hot water at 50 degrees C or ischaemia for 1 hr there was no increase in protein or enzyme concentrations in the lymph, although after the ischaemia there was an increase in lymph flow.3. After burning the limb at 60 degrees C there was a significant increase in the concentrations of the cytoplasmic enzymes glutamic-oxalacetic transaminase and lactic dehydrogenase, as a result of an increased permeability of the cell membrane.4. When the limb was burned at 80 degrees C there was a marked increase not only in the cytoplasmic enzymes but also in the mitochondrial enzyme glutamic pyruvic transaminase. Thus with the stronger burn the permeability of the intracellular mitochondrial membrane was also increased.5. Not until the most severe injury of all, i.e. freezing the limb solid, was there an increase in the concentration of lysosomal enzymes in the lymph.6. It is concluded that estimation of intracellular enzymes in the lymph draining an injured tissue affords a method of assessing the extent of cellular injury.