Abstract
The times of appearance and concentrations of dopa (DA), dopamine, norepinephrine and epinephrine were determined in the embryo and in the heart of the embryonic and developing chick. DA and dopamine were first detected in the heart on the 4th and 6th days of incubation, respectively. Cardiac norepinephrine and epinephrine were first detected on the 3rd day of incubation. The endogenous levels of these catecholamines and DA in the heart fluctuated throughout embryonic development and for a short time after hatching. During the remainder of development there were no further marked changes in their concentrations. In the whole embryo, DA and dopamine were first detected on the 1st and 2nd days, respectively. Norepinephrine and epinephrine were first detected on the 3rd day. As there appeared to be a somewhat orderly sequential appearance of these catechols, in the whole embryo, in accordance with the scheme for their biosynthesis, the order of appearance of each of the enzymes responsible for their synthesis was determined. Tyrosine hydroxylase, dopa decarboxylase, dopamine β-oxidase and phenylethanolamine-N-methyl transferase activities were first detected on the 1st, 2nd, 4th and 6th days of incubation, respectively.
Footnotes
- Received May 23, 1967.
- Accepted August 23, 1967.
- © 1968 by The Williams & Wilkins Company
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