Abstract
Catechol-O-methyl transferase (COMT) and monoamine oxidase (MAO) activities were measured in the heart and liver of the embryonic and developing chick. These enzymes were first detected in the embryonic heart on the 4th day and increased thereafter until the 10th day when their activities plateaued. Activities of both enzymes again increased on the 15th to 16th day and attained maximal values by the 19th day. Subsequently COMT and MAO exhibited sharp declines in their activities (to 13 and 40% of maximal values, respectively), reaching minimal values on the 2nd to 3rd day after hatching. After a gradual increase in enzyme activities through the next 6 to 7 days, COMT activity gradually declined and its activity could not be detected in the adult chicken, whereas MAO activity continually increased throughout development. In the embryonic liver the activities of both enzymes initially increased, attaining peak values on the 7th day. Subsequently, COMT and MAO activities declined, reaching minimal values on the 15th to 17th day of incubation. Following this, COMT activity increased slowly and MAO activity increased rapidly through the 10th day after hatching. An attempt was made to determine the possible causes of the observed fluctuations in cardiac COMT and MAO activities. Neither changes in protein concentration of tissue nor presence of activators or inhibitors appeared to account for the observed variations. Possible relationships between certain observed changes in heart rate and fluctuations in COMT and MAO activities, during development, have been suggested.
Footnotes
- Received May 23, 1967.
- Accepted August 23, 1967.
- © 1968 by The Williams & Wilkins Company
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|