Binding of apomorphine to neural membranes.
The intrinsic fluorescence of apomorphine has been used to measure its binding to neural membranes. A large number of relatively weak binding sites are concentrated in myelin and synaptic membrane fractions. Butyrophenones have the highest affinities for these sites--KD = 43 micrometer for haloperidol--while dopamine and dopamine releasers and reuptake blockers, as well as a variety of other alkaloids, have much lower affinities. The sites are hydrophobic and undergo a phase transition to a highly fluid state near 26 degrees C. Calcium is a noncompetitive inhibitor of apomorphine binding. Some of the actions of neuroleptic drugs may result from binding to these hydrophobic membrane sites in vivo, blocking conduction in small catecholamine axons.
D000818:Animals; D001058:Apomorphine / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D005453:Fluorescence; D066298:In Vitro Techniques; D007477:Ions; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature
D007477:Ions; D001058:Apomorphine