Table 1

Potencies of agonists in relaxing human circular and longitudinal (taenia) smooth muscle preparations

CircularTaenia
IC50(M)IAIC50(M)IA
(−)Isoprenaline2.1×10-8 (1.6–2.8)87 (9)1.4×10-7 (1.1–1.6)94 (6)
Terbutaline2.1×10-7 (0.9–3.4)60 (8)5.0×10-5 (3.7–6.6)63 (6)
CGP 12177ND18 (2) 1-150 1.1×10-6(0.6–2.5)33 (6)
SR58611AND13 (3)1-151 1.2×10-6 (0.4–3.2)31 (5)

  • Values are mean (95% confidence limits).

  • IC50, concentration producing 50% maximal response; IA, percentage intrinsic activity (percentage of the relaxing effect of papaverine); ND, not determinable.

  • ↵1-150 Maximal effect at 10−5 M;

  • ↵1-151 maximal effect at 10−4 M.