Comparison of three histochemical methods for assaying lactate dehydrogenase in liver

The mean activity of lactate dehydrogenase (LDH) in hepatocytes near the central vein region of unfixed sections of mouse liver was determined and compared with 3 different histochemical methods: conventional method, polyvinyl alcohol (PVA) method, and gel film method. An image analysis system was used for measuring the enzyme activity in single hepatocytes. The mean activities were approximately 1.4 and 2.7 times higher with the PVA and a gel film techniques respectively than with conventional aqueous media. The highest activity of LDH was obtained with gel media; this can be explained by the lowest diffusion late of this soluble cytoplasmic enzyme from the secretion into the medium. In the conventional technique, the apparent activity was found to be about 16% lower when sections were incubated vertically in a large volume of medium than when they were incubated horizontally in a small volume of medium.