Table 1

Potency of tachykinins, analogs, and antagonists as competitors against [125I]BH-SarSP in human colon circular muscle membranes

CompetitorSlope FactorpIC50nRelative Affinity
SP0.50H: 11.36  ± 0.14 (62%)5100
L: 9.18  ± 0.19 (38%)0.66
NKA0.63H: 9.51  ± 0.24 (45%)51.41
L: 7.78  ± 0.15 (55%)0.03
NPγ0.54H: 9.07  ± 0.11 (41%)30.51
L: 7.21  ± 0.07 (59%)0.007
[Pro9]SP0.59H: 11.05  ± 0.10 (78%)549
L: 9.08  ± 0.35 (22%)0.52
NKA analog1-a 1.046.88  ± 0.2240.003
Senktide1.054.30  ± 0.304<0.0001
CP999940.8210.48  ± 0.10413
SR489681.076.71  ± 0.5730.002
  • 1-a  NKA analog represents [Lys5, MeLeu9, Nle10]-NKA(4–10).