Biomaterial Database

Involvement of monoamine oxidase and noradrenaline uptake in the positive chronotropic effects of apigenin in rat atria. 1996

P S Lorenzo, and M C Rubio, and J H Medina, and E Adler-Graschinsky

Instituto de Investigaciones Farmacológicas, CONICET, Buenos Aires, Argentina. postmaster@invfar.edu.ar

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.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008995	Monoamine Oxidase	An enzyme that catalyzes the oxidative deamination of naturally occurring monoamines. It is a flavin-containing enzyme that is localized in mitochondrial membranes, whether in nerve terminals, the liver, or other organs. Monoamine oxidase is important in regulating the metabolic degradation of catecholamines and serotonin in neural or target tissues. Hepatic monoamine oxidase has a crucial defensive role in inactivating circulating monoamines or those, such as tyramine, that originate in the gut and are absorbed into the portal circulation. (From Goodman and Gilman's, The Pharmacological Basis of Therapeutics, 8th ed, p415) EC 1.4.3.4.	Amine Oxidase (Flavin-Containing),MAO,MAO-A,MAO-B,Monoamine Oxidase A,Monoamine Oxidase B,Type A Monoamine Oxidase,Type B Monoamine Oxidase,Tyramine Oxidase,MAO A,MAO B,Oxidase, Monoamine,Oxidase, Tyramine
D009638	Norepinephrine	Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic.	Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D009822	Oils, Volatile	Oils which evaporate readily. The volatile oils occur in aromatic plants, to which they give odor and other characteristics. Most volatile oils consist of a mixture of two or more TERPENES or of a mixture of an eleoptene (the more volatile constituent of a volatile oil) with a stearopten (the more solid constituent). The synonym essential oils refers to the essence of a plant, as its perfume or scent, and not to its indispensability.	Essential Oil,Oil, Essential,Oil, Volatile,Oils, Essential,Volatile Oil,Essential Oils,Volatile Oils
D010946	Plants, Medicinal	Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.	Herbs, Medicinal,Medicinal Herbs,Healing Plants,Medicinal Plants,Pharmaceutical Plants,Healing Plant,Herb, Medicinal,Medicinal Herb,Medicinal Plant,Pharmaceutical Plant,Plant, Healing,Plant, Medicinal,Plant, Pharmaceutical,Plants, Healing,Plants, Pharmaceutical
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D005260	Female		Females
D005419	Flavonoids	A group of phenyl benzopyrans named for having structures like FLAVONES.	2-Phenyl-Benzopyran,2-Phenyl-Chromene,Bioflavonoid,Bioflavonoids,Flavonoid,2-Phenyl-Benzopyrans,2-Phenyl-Chromenes,2 Phenyl Benzopyran,2 Phenyl Benzopyrans,2 Phenyl Chromene,2 Phenyl Chromenes
D006325	Heart Atria	The chambers of the heart, to which the BLOOD returns from the circulation.	Heart Atrium,Left Atrium,Right Atrium,Atria, Heart,Atrium, Heart,Atrium, Left,Atrium, Right
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia