ISSN:
1432-1912
Keywords:
Monoamine oxidase A and B
;
Noradrenaline
;
Clorgyline
;
(−)Deprenyl
;
Oxidative deamination
;
Electrical stimulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Specific inhibitors of MAO A (clorgyline 0.1 μmol/l) and of MAO B [(−)deprenyl 10 μmol/l] were used in dog saphenous vein strips in order to study the relative influence of the two types of MAO on: 1. Termination of contractile response to exogenous noradrenaline (NA); 2. Metabolism and accumulation of exogenous (3H)-NA; 3. Metabolism of3H-NA released by electrical stimulation. 1. To study the termination of contractile response to exogenous NA, the oil immersion technique was used to determine the time for half-relaxation. The experiments were performed on strips with or without treatment with cocaine 10 μmol/l (to inhibit neuronal uptake) plus U-0521 100 μmol/l (to inhibit catechol-O-methyl transferase) before and after exposure to MAO inhibitors. Clorgyline, but not (−)deprenyl enhanced significantly the time for half-relaxation of the strips, whether cocaine was present or not. 2. To study the metabolism and accumulation of exogenous3H-NA, the strips were incubated (with or without preincubation with cocaine) with3H-NA 0.23 μmol/l and 2.3 μmol/l in the presence and in the absence of MAO inhibitors. The formation of deaminated metabolites was significantly reduced by clorgyline, but not by deprenyl. 3. To study the metabolism of3H-NA released by electrical stimulation, the strips were incubated with3H-NA 1.4 μmol/l. In the presence of cocaine and U-0521, field stimulation was applied during two periods of 5 min (10 Hz, 100 V, 2 ms), in the absence or presence of MAO inhibitors. Under these experimental conditions clorgyline, but not deprenyl, abolished DOPEG formation, without affecting the other metabolites. In conclusion, only MAO A seems to be important for the inactivation of noradrenaline.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00692908
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