INFLUENCE OF AGE ON RECOVERY OF CARDIAC MONOAMINE OXIDASE AFTER IRREVERSIBLE INHIBITION

The level of monoamine oxidase (MAO) activity of rat heart is dependent on the age of the animal. Activity appears at 1-2 weeks after birth and increases progressively for the following 16-18 weeks. Thereafter the enzyme level remains fairly constant. Irreversible inhibition of cardiac MAO by administration of pargyline is followed by complete recovery of the enzyme, but the rate and duration of recovery are dependent on the age at which inhibition is produced. Thus, pargyline administration to 1-week-old rats resulted in a recovery curve which did not differ from that of controls. Total recovery of cardiac MAO, which was inhibited in rats 8 and 16 weeks old, required 6-8 weeks, with the initial rates of recovery being greater for the older animals. © 1968.