Monoamine oxidase activities in catfish (Parasilurus asotus) tissues.
The substrate- and inhibitor-related characteristics of monoamine oxidase (MAO) were studied for catfish brain and liver. The kinetic constants for MAO in both tissues were determined using 5-hydroxytryptamine (5-HT), tyramine and beta-phenylethylamine (PEA) as substrates. For both tissues, the Vmax values were highest with 5-HT and lowest with PEA. The Km value for the brain was highest with 5-HT, followed by tyramine and PEA; but for the liver its value was highest with PEA, followed by 5-HT and tyramine, although all values were in the same order of magnitude. The inhibition of MAO by clorgyline and deprenyl by use of 5-HT, tyramine and PEA as substrates showed that the MAO-A inhibitor clorgyline was more effective than the MAO-B inhibitor deprenyl for both catfish tissues; a single form was present since inhibition by clorgyline or deprenyl with 1000 microM PEA showed single phase sigmoid curves. It is concluded that catfish brain and liver contain a single form of MAO, relatively similar to mammalian MAO-A.
Kumazawa
T
T
Department of Legal Medicine, Showa University School of Medicine, Tokyo, Japan.
Seno
H
H
Ishii
A
A
Suzuki
O
O
Sato
K
K
D000818:Animals; D001921:Brain / Q000201:enzymology; D002397:Catfishes / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology
D008996:Monoamine Oxidase Inhibitors; D008995:Monoamine Oxidase