Multiple tachykinin binding sites in hamster, rat and guinea-pig urinary bladder.
Binding of the 125I-Bolton-Hunter labelled tachykinins substance P, substance K, eledoisin and neuromedin K (BHSP, BHSK, BHE, BHNK) was examined in urinary bladders of hamster, rat and guinea-pig using crude membrane suspensions and by autoradiography. High-affinity binding of BHSK was observed in hamster and rat bladder and high-affinity binding of BHSP was seen in rat and guinea-pig bladder. Characterization of this binding showed that the hamster bladder contains very large numbers of K-type binding sites, where BHSK is displaced by substance K greater than kassinin greater than eledoisin greater than neuromedin K greater than substance P greater than physalaemin, and has very few P-type binding sites, where BHSP is displaced by substance P greater than substance K much greater than neuromedin K. In contrast, the rat bladder contains moderate and approximately equal numbers of both K (KD, 0.74 nM; Bmax 2.9 fmol/mg wet weight tissue) and P (KD, 0.12 +/- 0.01 nM; Bmax 2.6 +/- 0.2 fmol/mg wet weight tissue) sites. The guinea-pig bladder possesses predominantly P sites. Most tachykinin binding sites are localized over smooth muscle and probably represent functional receptors mediating the direct contractile effects of tachykinins in these tissues. Few E-type binding sites, as previously described in rat brain, were found, although some BHNK binding sites were seen in the mucosa of guinea-pig bladder.
D000818:Animals; D001345:Autoradiography; D006224:Cricetinae; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008647:Mesocricetus; D009479:Neuropeptides / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D018039:Receptors, Tachykinin; D013045:Species Specificity; D015320:Tachykinins; D001743:Urinary Bladder / Q000378:metabolism*
D007457:Iodine Radioisotopes; D009479:Neuropeptides; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D015320:Tachykinins