Existence of postsynaptic dopamine D2 receptor as an enhancer of contractile response in vas deferens.
Effects of dopamine and (+/-)-2-(N-phenylethyl-N-propyl)amino-5-hydroxy-tetralin hydrochloride (N-0434), a dopamine D2 receptor agonist, in the presence of prazosin on the ATP- and acetylcholine-induced contraction were investigated in the guinea-pig vas deferens in order to test for the existence of postsynaptic dopamine receptors. The contraction induced by ATP was potentiated by dopamine and N-0434. This potentiation was antagonized by spiperone, a dopamine D2 receptor antagonist, but not by a dopamine D1 receptor antagonist and an alpha2-adrenoceptor antagonist. Similar results were also observed by acetylcholine as well as ATP. The contraction induced by transmural nerve stimulation in the presence of alpha-adrenoceptor antagonists was also potentiated by N-0434, and this potentiation was antagonized by spiperone. The results suggest that dopamine D2 receptors are located on the postsynaptic site of guinea-pig vas deferens and that the contractile responses to ATP and acetylcholine are potentiated via activation of dopamine D2 receptor.
Morishita
H
H
Department of Pharmacology, School of Medicine, Fukuoka University, Japan.
Katsuragi
T
T
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D004298:Dopamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010627:Phenethylamines / Q000494:pharmacology*; D017448:Receptors, Dopamine D2 / Q000187:drug effects* / Q000502:physiology; D013134:Spiperone / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects* / Q000502:physiology
D018491:Dopamine Agonists; D010627:Phenethylamines; D017448:Receptors, Dopamine D2; D013134:Spiperone; C041369:2-(N-phenethyl-N-propyl)amino-5-hydroxytetralin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D004298:Dopamine