[Defect in deamination of biogenic amines in spontaneous hypertension].

Activity of monoamine oxidases (MAO) of the types A and B (substrates: 5-hydroxytryptamine, 2-phenylethylamine, tyramine) has been studied in mitochondrial fractions from brain, heart, liver and kidney of 24-week-old rats of the normotonic strain Wistar Kyoto (WKY) and spontaneously hypertonic rats (SHR). As compared with the WKY rats, in the SHR strain the activity of MAO-A in heart mitochondria was increased 1.5-1.

[Inhibition of brain monoamine oxidase in the rat by multiple pyrazidol administration].

Pyrazidol, which is chemically 2,3, 3a, 4, 5, 6-hexahydro-8-methyl-1H-pyrazino[3,2,1-j,k] carbazole hydrochloride (international name pirlindole) administered repeatedly (21 days) to rats at a dose of 25 mg/kg per os maintained the selectivity of its inhibitory effect toward type A MAO. When administered repeatedly the inhibitory effect of pyrazidol was 1.5-2-fold higher than after a single administration.

[Inhibition of gamma-amylase of the rabbit liver by biogenic amines and products of their oxidative deamination].

Products of oxidative deamination of biogenic amines (aldehydes) exhibited an inhibitory effect on rabbit liver gamma-amylase activity. The aldehydes, formed after serotonin and 2-phenylethylamine oxidation, proved to be most effective in these systems. Dopamine, noradrenaline and tyramine also caused a slight inhibitory action under these conditions.

[Selective inhibition by pyrazidol of monoamine oxidase type A in different human and animal tissues].

Pyrazidol (2,3,3a,4,5,6-Hexahydro-8-methyl-1-H-pyrazino (3,2,1-j,k) carbazol hydrochloride) blocked selectively the type A monoamine oxidase (MAO) in mitochondria of different human and animal tissues, irrespective of substrate specificity of the type A MAO in the tissues studied. Thus, in tissues containing both types of MAO (rat, bovine and human brain, rat liver and intestine tissues) pyrazidol inhibited selectively the deamination of serotonin and did not affect the deamination of 2-phenylethylamine--the main substrates in these tissues of the type A and the type B MAO, respectively. In human placenta and rat heart containing only the type A MAO, which catalyzes deamination of 2-phenylethylamine, pyrazidol also inhibited the deamination of serotonin, tyramine and 2-phenylethylamine at comparatively low concentrations and in equal degree.

[Properties of intestinal monoamine oxidase in the rat].

Monoamine oxidase (MAO) activity (substrate: tyramine) has been studied in rat intestinal wall mitochondrial fractions identified by monitoring succinate dehydrogenase and cytochrome oxidase activities. The MAO activity, which was not due to contamination with mitochondria, has been also found in nuclear and microsomal (+hyaloplasm) fractions. Deamination of tyramine, serotonin and dopamine by rat intestinal mitochondrial MOA obeyed the Michaelis--Mentern kinetics.