Abstract
The uptake of tritium-labeled norepinephrine (H5-NE) and epinephrine (H3-E), as well as the subcellular distribution of H3-NE, was studied in the embryo and embryonic heart of the chick. Whole embryos and embryonic hearts took up H3-NE and H3-E early during development. Increasing amounts of these catecholamines were taken up through the 4th day. After a marked decrease of uptake on the 5th day by both the embryo and the heart, there occurred a gradual increase in H3-NE and H2-E uptake from the 6th through the 10th day. In embryonic hearts, H3-NE was found exclusively in the soluble fraction until the 5th day when uptake by the microsomal fraction occurred. The amount of exogenous H5-NE in the microsomal fraction relative to that in the soluble fraction in the heart increased with age and appeared to parallel the development of the sympathetic innervation to the heart. H5-NE was found primarily in the microsomal fraction in the 3-to 5-day-old whole embryo. Reserpine, cocaine and low temperatures effected a marked reduction in the capacity of whole embryos and innervated hearts to take up H8-NE. The effects of these agents on noninnervated hearts were much less marked. Reserpine and cocaine also markedly inhibited the distribution of administered H3-NE to the microsomal fractions in both embryos and innervated hearts. Yolks of fertilized and unfertilized eggs were found to contain NE and E but not dopa or dopamine. A movement of NE and E from the yolk to the whole embryo appears to occur on the 4th day of incubation.
Footnotes
- Received May 23, 1967.
- Accepted August 23, 1967.
- © 1968 by The Williams & Wilkins Company
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