title: Heterogeneity of high affinity nitrobenzylthioinosine binding sites in mammalian cortical membranes: multiple forms of central nervous system nucleoside transporters?
abstract: Specific binding of [3H]nitrobenzylthioinosine to cortical membranes from several mammalian species was investigated. Rat, mouse, guinea pig, and dog membranes contained an apparent single class of binding sites; there was, however, a marked species-dependent variation in their affinity for [3H]nitrobenzylthioinosine. Rabbit cortical membranes contained two classes of binding sites and the high and low affinity components were similar to those found in guinea pig and dog cortical membranes, respectively. The [3H]nitrobenzylthioinosine binding sites in rat and the low affinity sites in rabbit were atypical in that they exhibited a low affinity for dipyridamole. It is proposed that these latter sites may represent a form of the central nervous system nucleoside transport system which is less susceptible to inhibition by dipyridamole.
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive; D001693:Biological Transport, Active; D002540:Cerebral Cortex / Q000378:metabolism*; D004176:Dipyridamole / Q000494:pharmacology; D004285:Dogs; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007288:Inosine / Q000031:analogs & derivatives*; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D051379:Mice; D009705:Nucleosides / Q000378:metabolism*; D011817:Rabbits; D013045:Species Specificity; D013868:Thioinosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D009705:Nucleosides; D013868:Thioinosine; D007288:Inosine; D004176:Dipyridamole; C001789:4-nitrobenzylthioinosine