Abstract
During perfusion with tyrosine-C14-containing solution, norepinephrine-C14 is synthesized in the cat spleen. Rapid nerve stimulation results in release of norepinephrine-C14 having a greater specific activity than that found in the spleen, indicating that the newly synthesized norepinephrine is selectively released. When spleens from cats which had been treated with norepinephrine-H3 were perfused, the specific activity of norepinephrine released initially was similar to that in the spleen. After a period of continuous nerve stimulation, however, when the immediately available stores were depleted, the specific activity fell to about one-third that found in the spleen. If the perfusing solution contained α-methyltyrosine, an inhibitor of norepinephrine synthesis, initial release was not altered. At later times, however, only about one-third as much norepinephrine was released and the specific activity of the released catecholamine was similar to that in the spleen. These results suggest that, during continued rapid stimulation, mobilization of stored norepinephrine does not play as great a role in maintenance of transmitter release as does new synthesis.
Footnotes
- Received December 15, 1967.
- Accepted February 22, 1968.
- © 1968 by The Williams & Wilkins Company
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