Dopamine receptors in the guinea-pig heart. A binding study.
The binding of dopaminergic agonists and antagonists to guinea-pig myocardial membrane preparations was studied using 3H-dopamine and 3H-spiperone as radioligand. 3H-Dopamine bound specifically to heart membranes while 3H-spiperone did not. A Scatchard analysis of 3H-dopamine binding showed a curvilinear plot indicating the presence of two dopamine receptor populations that we have termed high- (Kd = 1.2 nM, Bmx = 52.9 fmol/mg prot.) and low- (Kd = 11.8 nM, Bmx = 267.3 fmol/mg prot.) affinity binding sites, respectively. The characterisation of the high-affinity component of 3H-dopamine binding indicated that the binding is rapid, saturable, stereospecific, pH- and temperature-dependent, and displaced by dopaminergic agonists and antagonists known to act similarly in vivo. The finding that pretreatment with dibenamine (which has been described as an alpha-adrenoceptor irreversible blocker) did not affect the binding of dopamine to cardiac membrane preparations suggests that alpha-adrenoceptors and dopamine receptors have separate recognition sites in the heart. We conclude that 3H-dopamine binds to specific dopamine receptors in the heart of guinea-pigs.
D000818:Animals; D002474:Cell-Free System; D004298:Dopamine / Q000378:metabolism; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D010646:Phentolamine / Q000378:metabolism; D011954:Receptors, Dopamine / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism; D013134:Spiperone / Q000378:metabolism; D013696:Temperature
D011954:Receptors, Dopamine; D013134:Spiperone; D004298:Dopamine; D010646:Phentolamine