Antagonist | m1/M1 | m2/M2 | m3/M3 | m4/M4 |
---|---|---|---|---|
PZ | 5–13 | 200–500 | 80–200 | 25–80 |
AF-DX 116 | 200–400 | 50–80 | 1260–1600 | 250–300 |
METH | 25–80 | 5–15 | 125–1000 | 8–23 |
These values, compiled from the literature (Caulfield, 1993;Waelbroeck et al., 1990), were obtained in radioligand-binding displacement studies using either tissue expressing a single muscarinic receptor subtype or cloned muscarinic receptors expressed in cell lines. The K d values for PZ, AF-DX 116 and METH obtained in the present study (table 1) were comparable to the values in this table and demonstrated that spinal cord contains M2, M3 and M4 receptors.