Antagonistic effect of N-methyltyramine on alpha2-adrenoceptor in mice.
We examined the effect of N-methyltyramine (NMT) on alpha2-adrenoceptor. NMT (10(-8)-10(-3) M) inhibited the binding of [3H]p-aminoclonidine to alpha2-adrenoceptor dose-dependently. However, the IC50 value for NMT (5.53 x 10(-6) M) was higher than that for RX821002, an alpha2-adrenoceptor antagonist (1.07 x 10(-8) M). RX821002 (5 mg/kg, i.p.) inhibited hypermotility induced by scopolamine (8 mg/kg, s.c.) in male ddY mice. NMT (20 or 100 mg/kg, i.p.) was found to have a dose-dependent inhibitory effect similar to that of RX821002. These findings indicate that NMT has the properties of an alpha2-adrenoceptor antagonist. However, the affinity of NMT for alpha2-adrenoceptor is weaker than that of RX821002.
Koda
H
H
Products Safety & Alcohol Science Laboratory, Suntory Limited, Mishima-gun, Osaka, Japan.
Yokoo
Y
Y
Matsumoto
N
N
Suwa
Y
Y
Fukazawa
H
H
Ishida
H
H
Tsuji
K
K
Nukaya
H
H
Kuriyama
K
K
D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000378:metabolism / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D019329:Idazoxan / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D051379:Mice; D011869:Radioligand Assay; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D012601:Scopolamine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014439:Tyramine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology
D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018341:Receptors, Adrenergic, alpha-2; C016986:apraclonidine; D012601:Scopolamine; C058525:2-methoxyidazoxan; C036244:methyl-4-tyramine; D003000:Clonidine; D014439:Tyramine; D019329:Idazoxan