Abstract
The fate of H3-norepinephrine has been investigated after intravenous injection into animals. In cats, it distributes unequally in the various tissues examined; it is selectively taken up and retained by heart, spleen and adrenal gland. After H3-norepinephrine administration H3-normetanephrine is found in all tissues analyzed, but the individual concentrations vary considerably; it is retained by tissues to a lesser extent than H3-norepinephrine, except in skeletal muscle where more H3-normetanephrine is found after 2 hours than after 2 minutes.
In the whole mouse H3-norepinephrine disappears rapidly at first, but then relatively slowly. H3-normetanephrine accounts for most of the H3-norepinephrine that disappears early in these experiments.
The importance of binding as a mechanism for the inactivation of circulating catecholamines is emphasized, and it is shown to be quantitatively more important for norepinephrine than for epinephrine. Differences in the degree of binding explain why H3-norepinephrine disappears more slowly than H3-epinephrine from blood and from tissues.
Footnotes
- Received November 4, 1960.
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