Activities of glycolytic and citric acid cycle enzymes in oral leukoplakia.

Abstract

abstract— Biopsies of homogeneous leukoplakias and non‐involved oral mucosa were obtained from the same patient, and buccal mucosa samples were obtained from individuals free of oral mucous membrane disease. Activities of glucose‐6‐phosphate dehydrogenase (G6PDH), pyruvate kinase (PK), glycerol‐3‐phosphate dehydrogenase (G3PDH), NAD and NADP dependent isocitrate dehydrogenases (ICDH) were quantitated in microdissected specimens of the superficial third of the epithelium. ICDH (NAD) was measured photo‐kinetically with the aid of a bioluminescent system. The remaining enzymes were assayed according to the techniques developed by lowry and co‐workers. The activities of G6PDH and G3PDH in non‐involved mucosa of leukoplakia patients were double those of mucosa from healthy controls. The activities of PK and ICDH (NAD and NADP) in these two groups of lesion‐free mucosa were similar. Non‐involved mucosa differed from leukoplakias with respect to the two ICDH's. In hyperorthokeratinized leukoplakias, NAD and NADP dependent ICDH activities were decreased by 59% and 37%, respectively. The values for the two ICDH's in hyperparakeratinized lesions lay between the levels of activity in noninvolved mucosa and hyperorthokeratotic leukoplakias but did not differ significantly from either.