Figure - PMC

Skip to main content

View full-text article in PMC

. Author manuscript; available in PMC: 2010 Aug 1.

Published in final edited form as: Neuropsychopharmacology. 2009 Dec 2;35(3):806–817. doi: 10.1038/npp.2009.189

A. [³H]Raclopride binding in competition with sulpiride. A two-site binding curve was observed in control cells (, Q−). Most D₂ receptors (85.8%) were on the surface and showed high-affinity (Ki_(s)= 7.7 ± 2.3 nM). A small proportion (14.2%) were internalized and showed low affinity binding (Ki_(i)= 141.8 ± 45.2 μM). Following quinpirole treatment ( , Q+), 43.1% of D₂ receptors remained on the surface (Ki_(s)= 7.9 ± 3.0 nM) and 56.9% were internalized (Ki_(i)= 120.7 ± 35.8 μM). B. [³H]NMSP binding in competition with raclopride. Competition experiments showed indistinguishable one-site binding curves between control (, Q−; K_i= 0.26 ± 0.09 nM) and quinpirole treated cells ( , Q+; K_i= 0.28 ± 0.05 nM). Thus, like NMSP, raclopride readily accesses internalized D₂ receptors.

Inline graphic — A. [³H]Raclopride binding in competition with sulpiride. A two-site binding curve was observed in control cells (, Q−). Most D₂ receptors (85.8%) were on the surface and showed high-affinity (Ki_(s)= 7.7 ± 2.3 nM). A small proportion (14.2%) were internalized and showed low affinity binding (Ki_(i)= 141.8 ± 45.2 μM). Following quinpirole treatment ( , Q+), 43.1% of D₂ receptors remained on the surface (Ki_(s)= 7.9 ± 3.0 nM) and 56.9% were internalized (Ki_(i)= 120.7 ± 35.8 μM). B. [³H]NMSP binding in competition with raclopride. Competition experiments showed indistinguishable one-site binding curves between control (, Q−; K_i= 0.26 ± 0.09 nM) and quinpirole treated cells ( , Q+; K_i= 0.28 ± 0.05 nM). Thus, like NMSP, raclopride readily accesses internalized D₂ receptors.