[Monoamine oxidase activity in rat liver in vitamin B12 deficiency].

Changes in the activity of monoamine oxidase (MAO-B) in liver homogenates and mitochondria from normal and vitamin B12-deficient rats have been studied in various functional states of the mitochondria. Preincubation of liver preparation at 32 degrees C increased the MAO affinity for benzylamine in samples of normal (but not vitamin B12-deficient rats). Succinate added to the incubation medium decreased Km and increased Vmax in both normal and vitamin B12-deficient animals. A correlation was found between the decline of MAO-B activity under vitamin B12 deficiency, deceleration of succinate oxidation and reduction of the transmembrane potential.