Involvement of monoamine oxidase and noradrenaline uptake in the positive chronotropic effects of apigenin in rat atria.
Eur J Pharmacol
; 312(2): 203-7, 1996 Sep 26.
Article
in En
| MEDLINE
| ID: mdl-8894597
In rat isolated atria spontaneously beating and labelled with [3H]noradrenaline, exposure to the flavonoid apigenin increased the atrial rate in a concentration-dependent manner (0.01-30 microM). This increase was accompanied by a reduction of 60% in the uptake of [3H]noradrenaline as well as by a modification in the pattern of [3H]noradrenaline and metabolites spontaneously released. Sixty minutes after exposure to 30 microM apigenin, the proportion of unmetabolized [3H]noradrenaline increased from 11% to 45% of the total products collected in the organ bath whereas the tritiated O-methylated deaminated metabolites decreased from 33% to 14% of the total efflux. A small but significant decrease in the outflow of [3H]3,4-dihydroxymandelic acid as well as a tendency to a decrease in the efflux of [3H]3,4-dihydroxyphenylglycol was also observed. Furthermore, apigenin inhibited in a concentration-dependent manner the activity of monoamine oxidase in the rat atrial homogenates. The calculated IC50 (7.7 microM) was within the range that produced 50% of the maximal increase in atrial rate. It is concluded that apigenin possesses the property to increase the atrial rate, probably as a result of a reduction in noradrenaline uptake as well as in monoamine oxidase activity.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Flavonoids
/
Oils, Volatile
/
Norepinephrine
/
Enzyme Inhibitors
/
Heart Atria
/
Monoamine Oxidase
Limits:
Animals
Language:
En
Journal:
Eur J Pharmacol
Year:
1996
Document type:
Article
Affiliation country:
Argentina
Country of publication:
Netherlands