Changes of Catecholamine Metabolic Enzymes in Rat Liver during 2 Weeks of Head-down Suspension

ABSTRACT

During simulated weightlessness and spaceflight, variations in plasma and urinary catecholamine(GA) levels haute been observed. The alterations of metabolism of CA In liver, the main site of metabolism, ate yet not known We measured the activity of catechol-O-methyl transferase (COMT) and monoamine oxidase (MAO) In rat liver as Indicators of CA metabolism before and during head-down suspension The rats were placed In a -45 degress antiorthostatic position for 2 weeks. Head-down suspension resulted In decrease other hepatic MAO B activity By contrast, the activities of other hepatic degrading enzymes, COMT and MAO A, did not altered These findings Indicate that a prolonged exposure to simulated weightlessness exerts no remarkable effect on CA degradation in rat liver.