Lactate dehydrogenase isozymes in developing rat oral mucosa. A comparative study of LDH biochemistry and histochemistry.

Histochemical lactic acid dehydrogenase (LDH) staining methods seem unable to demonstrate the total LDH activity in tissue sections. An analysis was made of LDH tissue staining methods applied on LDH zymograms. The menadione-mediated LDH staining of tissue sections can not possibly reflect true LDH activity. The addition of cyanide also slightly inhibited LDH activity. The cyanide inhibition was confirmed via LDH assay and found to be competitive in character. It is concluded that cyanide and menadione should be replaced by agents suitable from both a histochemical and a biochemical point of view. Based on the findings of this study the presence of LDH in oral epithelium was analyzed. Evidently LDH of the oral epithelium is basically anaerobic in character and located primarily in spinosum/granulosum layers and only sparsely in the basal layer.