Dopamine binding to the alpha receptor in pregnant rabbit myometrium.
This study evaluated in vitro binding of dopamine ligands to myometrial alpha adrenoceptors. With cell membranes from pregnant rabbits, receptor radioligand binding studies utilizing [3H] dihydroergocryptine +/- dopamine demonstrated receptor affinity (KD) = 0.75 +/- 0.10 nM (+/- SEM) and density (Bmax) = 533.2 +/- 45.2 fM/mg protein. Similar studies utilizing phentolamine or apomorphine gave essentially identical results. Competition binding studies demonstrated steriospecific butaclamol binding, along with significant binding of haloperidol, spiperone, apomorphine, and bromoergocryptine. These observations provide a mechanism for the observed uterotonic effects of dopamine.
D000818:Animals; D001058:Apomorphine / Q000378:metabolism; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D004088:Dihydroergotoxine / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D009215:Myometrium / Q000378:metabolism*; D010646:Phentolamine / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D004088:Dihydroergotoxine; D001058:Apomorphine; D004298:Dopamine; D010646:Phentolamine