IT IS WELL known that the metabolic reactions of living matter are catalyzed by enzymes and are also mutually controlled through other metabolic systems. Pyridinenucleotides such as *nicotinamide-adenine dinucleotide (NAD), nicotinamide-adenine dinucleotide reduced (NADH), nicotinamide-adenine dinucleotide phosphate (NADP), and nicotinamide-adenine dinucleotide phosphate reduced (NADPH) play an important part in such regulation. The purpose of this investigation was to assess their importance in the metabolic activity of the cochlea.
The rate of oxidation of NADH by the labyrinthine fluids from living mammals was measured. Similar determinations were made with cerebrospinal fluid and blood serum. The NADH-oxidation rate of the fluids from animals treated with kanamycin sulfate was also studied. Since this drug causes degeneration of certain tissues,1,2 a change in the enzyme activity of the surrounding fluids may be expected to be similar to the changes in enzyme activity seen in the blood serum associated with some degenerative diseases.
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