Nicotinamide-adenine dinucleotide-methemoglobin reductase activity in erythrocytes from cats.

Reduced nicotinamide-adenine dinucleotide (NADH)-methemoglobin reductase activity in feline erythrocyte lysates was determined, using potassium ferricyanide as substrate. The optimum conditions for the assay were pH 8 and 37 C. Mean NADH-ferricyanide reductase activity in cats was 15.7 +/- 4.1 mumoles of substrate converted/g of hemoglobin/min. The migration of NADH-ferricyanide reductase was similar to that of the NADH-methemoglobin reductase (NADH diaphorase) on starch gel electrophoresis.