title: IP3 receptor antagonist heparin uncompetitively inhibits [3H](+)-SKF-10047 binding to sigma receptors.
abstract: Interaction of sigma receptors with intracellular Ca2+ channel blocker and modulators was examined. Ryanodine and inositol 1,4,5-trisphosphate (IP3) did not inhibit [3H](+)-N-allylnormetazocine ([3H](+)-SKF-10047) binding to sigma receptors from either brain microsomal fractions or liver membrane extracts of the rat. However, the IP3 receptor antagonist heparin inhibited [3H](+)-SKF-10047 to sigma receptors in an uncompetitive manner with a Ki of 93 microM. These results suggest that sigma receptors may bear some relationship with IP3 receptor associated proteins or channels.
authors.affiliation: Unit on Pathobiology, National Institute on Drug Abuse/N.I.H., Baltimore, MD 21224, USA.
authors.forename: L I
authors.initials: LI
authors.lastname: Tsao
authors.forename: T P
authors.initials: TP
authors.lastname: Su
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology*; D066298:In Vitro Techniques; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007700:Kinetics; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010620:Phenazocine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry*; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors* / Q000187:drug effects; D012433:Ryanodine / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D017465:Receptors, Opioid, delta; D012433:Ryanodine; C012134:SK&F 10047; D006493:Heparin; D010620:Phenazocine