Image analysis for histochemical study of glucose-6-phosphatase inactivation by diethyl pyrocarbonate in normal human liver.

Glucose-6-phosphatase (G6Pase) is a multicomponent system that catalyzes G6P hydrolysis. To determine the specificity of the histochemical reaction of G6Pase, we investigated the inhibitory effect of diethyl pyrocarbonate (DEPC), a specific and very effective inhibitor of the phosphohydrolase component of the G6Pase system, in normal human liver. The inactivation of the histochemical enzymatic activity by DEPC was monitored by determining the mean brightness of the microscopic image and the histogram of light intensity distributions. The results obtained indicate that the histogram is more sensitive than the mean brightness to variations of enzymatic activities, and that the percent of pixels brighter than a convenient level is directly proportional to DEPC concentration. This study indicates that DEPC can be used as an efficient inhibitor of the histochemical reaction of G6Pase.