<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ann Packeu</style></author><author><style face="normal" font="default" size="100%">Jean-Paul De Backer</style></author><author><style face="normal" font="default" size="100%">Georges Vauquelin</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Non-competitive interaction between raclopride and spiperone on human D-receptors in intact Chinese hamster ovary cells.</style></title><secondary-title><style face="normal" font="default" size="100%">Fundam Clin Pharmacol</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Animals</style></keyword><keyword><style  face="normal" font="default" size="100%">Binding Sites</style></keyword><keyword><style  face="normal" font="default" size="100%">Binding, Competitive</style></keyword><keyword><style  face="normal" font="default" size="100%">Cho Cells</style></keyword><keyword><style  face="normal" font="default" size="100%">Cricetinae</style></keyword><keyword><style  face="normal" font="default" size="100%">Cricetulus</style></keyword><keyword><style  face="normal" font="default" size="100%">Dopamine Antagonists</style></keyword><keyword><style  face="normal" font="default" size="100%">Dopamine D2 Receptor Antagonists</style></keyword><keyword><style  face="normal" font="default" size="100%">Dose-Response Relationship, Drug</style></keyword><keyword><style  face="normal" font="default" size="100%">Drug Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Raclopride</style></keyword><keyword><style  face="normal" font="default" size="100%">Receptors, Dopamine D2</style></keyword><keyword><style  face="normal" font="default" size="100%">Spiperone</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2010 Jun</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">24</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;We recently investigated the binding properties of the antagonists [(3)H]-raclopride and [(3)H]-spiperone to intact Chinese hamster ovary cells expressing recombinant human D(2long)-dopamine receptors (CHO-D(2L) cells). Compared with saturation binding with [(3)H]-raclopride, raclopride reduced [(3)H]-spiperone binding with to low potency in competition binding experiments. The present findings illustrate the ability of spiperone to inhibit [(3)H]-raclopride binding non-competitively. While raclopride only decreases the apparent K(D) of [(3)H]-raclopride in saturation binding experiments, spiperone only decreases the number of sites to which [(3)H]-raclopride binds with high affinity. Also, while the IC(50) of raclopride depends on the concentration of [(3)H]-raclopride in competition experiments, this is not the case for spiperone. Kinetic studies reveal that the binding of raclopride at its high affinity sites does not affect the association of subsequently added [(3)H]-spiperone nor the rebinding of freshly dissociated [(3)H]-spiperone to the same or surrounding receptors. Yet, spiperone does not affect the dissociation rate of [(3)H]-raclopride and raclopride does not affect the (genuine) dissociation rate of [(3)H]-spiperone. The easiest way to interpret the present findings in molecular terms is to assume that D(2L)-receptors or their dimeric complexes possess two distinct binding sites: one with high affinity/accessibility for [(3)H]-raclopride and the other one with high affinity/accessibility for [(3)H]-spiperone. The ability of bound spiperone to inhibit high affinity raclopride binding while the reverse is not the case suggests for the occurrence of non-reciprocal allosteric interactions. These new findings could point at the occurrence of allosteric interactions between different classes of D(2)-receptor antagonists.&lt;/p&gt;
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