THE CATECHOL-O-METHYL TRANSFERASE ACTIVITY AND ENDOGENOUS CATECHOLAMINE CONTENT OF VARIOUS TISSUES IN THE RAT AND THE EFFECT OF ADMINISTRATION OF U-0521 (3’,4’-DIHYDROXY-2-METHYL PROPIOPHENONE)

¹ Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota

The regulatory influence of COMT (catechol-O-methyl transferase) on the catecholamine content of various tissues was investigated. The COMT activity of the heart, brain, uterus and liver was inhibited by administration of U-0521. This agent increased the epinephrine but not the norepinephrine content of the uterus within a period of 1 hr. The norepinephrine concentration in the brain was also elevated but no significant changes occurred in the catecholamine content of the heart. The increases in catecholamines were probably due to the localized inhibition of COMT in the tissues where these changes occurred. The COMT activity of the uterus was greater during estrus as compared to diestrus and increased after estrogen administration to ovariectomized rats. The cyclic variation of the catecholamine content in the uterus could not be explained on the basis of these changes in COMT activity.