title: Multiple tachykinin binding sites in peripheral tissues and in brain.
abstract: Tachykinin binding sites in guinea pig urinary bladder (GPUB), rat salivary gland (RSG), hamster urinary bladder (HUB), rat vas deferens (RVD) and rat cerebral cortex (RCC) were compared using 125I-Bolton Hunter conjugates of substance P (125I-BHSP), eledoisin (125I-BHE) and neurokinin A (125I-BHNKA). In typical SP-P tissues (GPUB, RSG) and in RCC, SP was the most potent displacer of 125I-BHSP and [Glp6,D-Pro9]-SP(6-11) was 90 times less active than [Glp6,L-Pro9]-SP(6-11) while SP methyl ester (SPOMe) was 5-10 times more active than the Bolton Hunter conjugate of SPOMe (I-BHSPOMe). On the other hand, in typical SP-E tissues (HUB, RVD), neurokinin A was most potent in displacing 125I-BHE and [Glp6,D-Pro9]-SP(6-11) was over 300 times more active than [Glp6,L-Pro9]-SP(6-11) while SPOMe was 160 times less active than I-BHSPOMe. In rat cerebral cortex, the rank order of potency of tachykinins and related analogues in displacing 125I-BHE was distinct from that of peripheral SP-E sites, with neurokinin B being the most potent displacer, and SPOMe was over 1,000 times more active than I-BHSPOMe; 125I-BHE binding sites in CNS may represent a third category of tachykinin receptor, designated SP-N.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D018039:Receptors, Tachykinin; D013045:Species Specificity; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D014018:Tissue Distribution
chemical_list: D007457:Iodine Radioisotopes; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D013373:Substance P