RT Journal Article
SR Electronic
T1 THE EFFECT OF NERVE STIMULATION ON THE SYNTHESIS AND METABOLISM OF NOREPINEPHRINE IN THE ISOLATED GUINEA-PIG HYPOGASTRIC NERVE-VAS DEFERENS PREPARATION
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 61
OP 71
VO 160
IS 1
A1 Norman Weiner
A1 Mirjana Rabadjija
YR 1968
UL http://jpet.aspetjournals.org/content/160/1/61.abstract
AB Electrical nerve stimulation of the isolated hypogastric nerve-vas deferens preparation of the guinea-pig is associated with increased formation of H3-norepinephrine from H3-tyrosine. The effect is similar in the presence or absence of pargyline, a monoamine oxidase inhibitor. In contrast, nerve stimulation is not associated with a significant increase in the synthesis of H3-norepinephrine from H3-dihydroxyphenylalanine. The uptake of H3-tyrosine and its incorporation into tissue protein is not affected by nerve stimulation. The tissue content of norepinephrine and the metabolism of exogenous labeled norepinephrine are identical in stimulated and control preparations. Norepinephrine inhibits the synthesis of H3-norepinephrine from H3-tyrosine and blocks the accelerated synthesis of norepinephrine which is ordinarily seen during nerve stimulation. Pargyline slightly potentiates this inhibitory effect of norepinephrine. The results indicate that a relatively small pool of intraneuronal norepinephrine which is able to interact with tyrosine hydroxylase inhibits this enzyme and thus regulates its own synthesis by a feedback inhibition mechanism. It is proposed that nerve stimulation leads to a reduction in the concentration of that norepinephrine which can interact with the tyrosine hydroxylase. This results in activation of the normally inhibited enzyme and consequent acceleration of norepinephrine synthesis. © 1968 by The Williams & Wilkins Company