Abstract
The accumulation of H3-norepinephrine and its metabolites has been measured in cocaine-treated, isolated, perfused rat hearts. This accumulation appears to occur outside of sympathetic neurons. Adrenergic blocking agents reduce this extraneuronal concentration of H3-norepinephrine and the metabolites. The alpha-adrenergic blocking agents are more potent than the beta-adrenergic blocking agents. The decreased concentrations of the metabolites in the presence of the adrenergic blocking agents do not appear to be related to inhibition of catechol-O-methyl transferase or monoamine oxidase but rather to the reduced concentrations of norepinephrine. It is proposed that the adrenergic blocking agents may inhibit an extraneuronal transport mechanism, thereby reducing the access of norepmnephrine to the intracellular metabolizing enzymes.
Footnotes
- Received August 8, 1966.
- Accepted September 27, 1966.
- © 1967 by The Williams & Wilkins Company