Characterisation of a novel, selective radioligand, [125I][Lys5,Tyr(I2)7,MeLeu 9,Nle10]neurokinin A-(4-10), for the tachykinin NK2 receptor in rat fundus

Elizabeth Burcher, Tim Badgery-Parker, Xiang-Ping Zeng, Solange Lavielle

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22 Citations (Scopus)


The tyrosyl derivative of the tachykinin NK2 selective agonist [Lys5,MeLeu9,Nle10]NKA-(4-10) was iodinated and the product [125I][Lys5,Tyr(I2)2,MeLeu 9,Nle10]NKA-(4-10) purified using reverse phase HPLC. The binding characteristics of this novel radioligand were investigated in homogenates of rat gastric fundus. Binding was saturable, reversible and to a single population of high affinity sites of KD 1.3 ± 0.2 nM (n = 4). Specific binding of [125I][Lys5,Tyr(I2)7,MeLeu 9,Nle10 ]NKA-(4-10) was inhibited by neuropeptide γ SR 48968 ≥ neurokinin A (NKA) ≥ [Lys5,MeLeu9,Nle10]NKA-(4-10) > [Lys5,Tyr7,MeLeu9,Nle10]NKA- (4 -10) > neuropeptide K > [Lys5,Tyr(I2)7,MeLeu9,Nle 10]NKA-(4-10) > MDL 29,913 > [127I]-Bolton-Hunter-NKA > neurokinin B > substance P (SP) ≫ MEN 10207 > [Sar9,Met(O2)11]SP ≫ senktide, indicating binding to NK2 receptors. NKA, [Lys5,MeLeu9,Nle10]NKA-(4-10) and [Lys5,Tyr(I2)7,MeLeu9,Nle 10]NKA-(4minus;10) contracted the isolated fundus strip, with pD2 values 7.9, 7.7 and 7.4, respectively. This novel, highly selective radioligand should prove useful in characterisation studies in peripheral tissues.

Original languageEnglish
Pages (from-to)201-207
Number of pages7
JournalEuropean Journal of Pharmacology
Issue number2-3
Publication statusPublished - 23 Mar 1993
Externally publishedYes


  • Gastric fundus (rat)
  • Neurokinin A
  • Neuropeptide γ
  • NK receptors
  • Radioligand binding
  • Tachykinin

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