Table 1.
Effects of 4 different muscarinic antagonists on the response of BMVECs and bEnd.3 cells to 1 μM ACh.
| mAChR antagonist | BMVEC | bEnd.3 | Published reports | |||
|---|---|---|---|---|---|---|
| IC50 (nM) | Ka (nM) | IC50 (nM) | Ka (nM) | Receptor | Ki (nM) | |
| Telenzepine | 191.29 ± 28.51 | 33.98 | 162.08 ± 21.86 | 36.43 | M1 M3 | 2.5 20.774 |
| VU 0255035* | >104 | >1770 | >104 | >2250 | M1 M3 | 14.9 877**52, 57 |
| J104129 fumarate | 33.81 ± 3.80 | 6.00 | 43.31 ± 3.62 | 9.74 | M1 M3 | 19 4.275 |
| 4-DAMP | 1.96 ± 0.48 | 0.42 | 1.39 ± 0.25 | 0.31 | M1 M3 | 1 0.658, 76 |
Absolute IC50 values and affinity constants Ka were calculated based on eqs (2) and (3), respectively, from the data presented in Fig. 5. For comparison, previously reported affinity constants for M1 and M3 receptors (Ki), determined on individual clones expressed in testing cell lines, are also shown. *For VU 0255035, the absolute value of IC50 could not be established, due to this antagonist’s very low efficacy in blocking the calcium signal; **Ki values were determined via a radioligand binding assay52, 57, but the authors note that the Ki values obtained via a calcium mobilization assay could be at least two times higher than those determined in the radioligand binding assay.