Agent | Muscarinic Receptor Subtype | |||||
---|---|---|---|---|---|---|
rM1 | hM2 | rM3 | hM3 | hM4 | hM5 | |
Atropine | 0.004 ± 0.002 | 0.005 ± 0.000 | 0.012 ± 0.002 | N.D. | N.D. | N.D. |
Lithocholylcholine | 10.9 ± 0.5 | 15.9 ± 9.0 | 6.4 ± 0.8 | 12.6 ± 1.2 | 25.7 ± 1.4 | 14.0 ± 1.9 |
Acetylcholine | 40.1 ± 7.9 | 1.3 ± 2.1 | 15.2 ± 4.1 | 49.7 ± 4.4 | 28.4 ± 1.4 | 1.8 ± 0.1 |
Lithocholyltaurine | 152.2 ± 8.81-150 | N.B. | 165.1 ± 38.5 | >1000 | N.B. | N.B. |
Lithocholylglycine | 382.2 ± 43.81-150 | N.B. | 228.3 ± 41.2 | >1000 | 95.3 ± 2.2 | 183.4 ± 13.8 |
Carbachol | 467.4 ± 29.2 | 41.3 ± 17.9 | 399.2 ± 43.3 | 477.0 ± 31.8 | N.D. | N.D. |
IC50 values (micromolar) were obtained by computer analysis of dose-inhibition curves of [3H]NMS binding shown in Fig. 3using a nonlinear, least-squares curve-fitting program, LIGAND (Munson and Rodbard, 1980). Values are mean ± S.E.M. of at least three independent experiments.
N.D., not determined; N.B., no detectable competition for binding with the concentration range tested.
↵1-150 Value is approximate, as inhibition of radioligand binding did not reach 50% because of limited solubility of bile acids at higher concentration.