RT Journal Article SR Electronic T1 FATE OF NOREPINEPHRINE-H3 IN THE ISOLATED PERFUSED RAT HEART JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 34 OP 40 VO 138 IS 1 A1 Irwin J. Kopin A1 Georg Hertting A1 Edna K. Gordon YR 1962 UL http://jpet.aspetjournals.org/content/138/1/34.abstract AB The fate of norepinephrine-H3 has been investigated in the isolated perfused hearts of normal and reserpine pretreated rats. In normal hearts norepinephrine is inactivated primarily by binding. In perfused hearts from normal rats, O-methylation is the predominant pathway of metabolic inactivation. Reserpinized hearts have a decreased binding capacity, but a greater proportion of the infused norepinephrine is metabolized. The increase in metabolic products in the reserpinized hearts is confined to the deaminated catechols and their O-methylated derivatives. The presence of several types of binding is indicated by the observed multiphasic release of bound norepinephrine. It is suggested that the free, active, and easily released norepinephrine is metabolized by O-methylation, while the more firmly bound, reserpine depleted norepinephrine is deaminated without becoming active.