Characterization of NK-3 binding sites in rat and guinea pig cortical membranes by the selective ligand [3H]Senktide.
We have used [3H]Senktide, a selective Neurokinin B receptor ligand, for the characterization of NK-3 receptors in rat and guinea pig CNS membranes. Scatchard analysis of saturation binding studies in cerebral cortex membranes indicated that this ligand bound to a single site with apparent high affinity (KD = 4.6 +/- 1.6 and 3.1 +/- 0.37 nM, Bmax = 13.7 +/- 1.6 and 21.8 +/- 2.2 fmol/mg protein in rat and guinea pig membranes, respectively). However, in competition studies with a group of neurokinins and related peptides two different rank orders of affinities were obtained, as follows: NKB greater than [MePhe7]-NKB greater than or equal to Arg0-NKB greater than or equal to Senktide much greater than NKA greater than SP, in rat membranes, and [MePhe7]NKB greater than Senktide = NKB greater than Arg0-NKB much greater than SP greater than NKA, in guinea pig membranes.
Renzetti
A R
AR
Department of Pharmacology, Laboratori Guidotti S.p.A., Pisa, Italy.
Barsacchi
P
P
Criscuoli
M
M
Lucacchini
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D006168:Guinea Pigs; D007700:Kinetics; D008024:Ligands; D008297:Male; D008969:Molecular Sequence Data; D015287:Neurokinin B / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D018042:Receptors, Neurokinin-3; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013373:Substance P / Q000031:analogs & derivatives* / Q000378:metabolism
D008024:Ligands; D009479:Neuropeptides; D010446:Peptide Fragments; D018042:Receptors, Neurokinin-3; D017981:Receptors, Neurotransmitter; C054724:senktide; D013373:Substance P; D015287:Neurokinin B