A Histochemical Study of Corneal Respiratory Enzymes

Abstract

Introduction The demonstration of the localization and activity of various respiratory enzymes is helpful in the study of tissue metabolism. It is the purpose of this paper to identify and localize the activity of multiple dehydrogenases and diaphorases in the cornea of the adult rabbit and rat, utilizing nitro-blue tetrazolium (nitro-BT) as an intracellular biologic indicator. The basic principle of dehydrogenase histochemistry lies in the ability of the tetrazolium salt to intercept hydrogen or hydrogen electrons from the biologic system with a consequent reduction to a deeply colored formazan pigment.¹ A detailed account of the biochemical events may be found elsewhere.^2-9 To date, very few histochemical tetrazolium studies of the cornea have been reported. In 1954, Jaeger,¹⁰ utilizing the earliest tetrazolium salt, triphenyl tetrazolium chloride (TTC), reported dehydrogenase activity in bovine cornea homogenates by spectrophotometric measurements. Calculations were based on formazan/corneal dry weight. When added to the