[Harman and 3-methylharman--blockaders of presynaptic alpha 2-adrenoreceptors].
It has been shown in experiments on rat vas deferens that melipramine, harmane and 3-methylharman in low concentrations of the order of 10(-8)--10(-6) M increase the contraction of the vas deference induced by noradrenaline and transmural stimulation. Meanwhile in higher concentrations (10(-6)--4 X 10(-5) M) they have been discovered to decrease this effect (except for harmane). In low concentrations harmane and 3-methylharman competitively remove the inhibitory effect of clonidine on the transmural stimulation-induced contractions. It is inferred that harmane and methylharman are competitive blockers of presynaptic alpha 2-adrenoceptors in adrenergic synapses.
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006247:Harmine / Q000031:analogs & derivatives / Q000494:pharmacology*; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D014649:Vas Deferens / Q000187:drug effects
D000470:Alkaloids; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; C037116:3-methylharman; D006247:Harmine; C005010:harman; D003000:Clonidine; D007099:Imipramine; D009638:Norepinephrine
Garman i 3-metilgarman--blokatory presinapticheskikh al'fa 2-adrenoretseptorov.