Determination of the rate constant for neuronal and extra-neuronal monoamine oxidase
In the rat vas deferens, neuronal deamination of /sup 3/H-(-) noradrenaline (/sup 3/H-NA) to /sup 3/H-dihydroxyphenethylglycol (/sup 3/HDOPEG) cannot be inhibited by pretreatment with a monoamine oxidase (MAO) inhibitor. However, in the extraneuronal compartment of the rat heart, inhibition of MAO abolishes the formation of /sup 3/HDOPEG. To clarify this discrepancy, the authors determined the rate constant for MAO (/sup k/mao/) neuronally (rat vas deferens) and extraneuronally (rat heart). For neuronal /sup k/mao, vasa deferentia were incubated with /sup 3/HNA for 300 minutes, and the cumulative formation of /sup 3/HDOPEG measured. The delay in time before /sup 3/HDOPEG achieves steady state (/sup tau/system), is inversely proportional to /sup k/mao. Because /sup tau/system is very short for neuronal MAO, an appreciable delay was only achieved after partial inhibition of MAO with various parglyline concentrations. To relate to the uninhibited enzyme, the percentage inhibition by pargyline was then determined in homogenate preparations. For extraneuronal MAO, a similar procedure was performed in perfused rat hearts. Results show a significantly greater /sup k/mao of neuronal origin, (/sup k/mao = .57min/sup -/1) which when related to the fractional size of the neuronal compartment suggests a very high activity of neuronal MAO.
- Research Organization:
- Universitaet Wuerzburg, West Germany
- OSTI ID:
- 5451079
- Report Number(s):
- CONF-8604222-; TRN: 86-028347
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Multiple effects of sibutramine on ejaculation and on vas deferens and seminal vesicle contractility
Interaction of Xylamine with peripheral sympathetic neurons
Related Subjects
AMINE OXIDASES
ENZYME ACTIVITY
NORADRENALINE
DEAMINATION
ENZYME INHIBITORS
HEART
NERVES
RATS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ADRENAL HORMONES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CHEMICAL REACTIONS
DRUGS
ENZYMES
HORMONES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
NERVOUS SYSTEM
NEUROREGULATORS
ORGANS
OXIDOREDUCTASES
RODENTS
STEROID HORMONES
SYMPATHOMIMETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques