PT  - JOURNAL ARTICLE
AU  - SPECTOR, SYDNEY
AU  - GORDON, ROBERT
AU  - SJOERDSMA, ALBERT
AU  - UDENFRIEND, SIDNEY
TI  - End-Product Inhibition of Tyrosine Hydroxylase as a Possible Mechanism for Regulation of Norepinephrine Synthesis
DP  - 1967 Nov 01
TA  - Molecular Pharmacology
PG  - 549--555
VI  - 3
IP  - 6
4099  - http://molpharm.aspetjournals.org/content/3/6/549.short
4100  - http://molpharm.aspetjournals.org/content/3/6/549.full
SO  - Mol Pharmacol1967 Nov 01; 3
AB  - The present study was undertaken to evaluate the influence of endogenous norepinephrine content on the rate of norepinephrine synthesis in vivo. Tissue levels of norepinephrine were increased in guinea pigs by administration of a monoamine oxidase inhibitor and tyrosine-14C and DOPA-3H were used to measure norepinephrine synthesis. In brain and heart when norepinephrine levels were increased 2- to 3-fold, conversion of tyrosine-14C to norepinephrine was decreased markedly. When tyrosine hydroxylase was bypassed by administering DOPA-3H, conversion to norepinephrine was actually increased. These findings lend support to the hypothesis that norepinephrine synthesis is regulated by a mechanism of end-product inhibition at the tyrosine hydroxylase step.