TABLE 1

Radioligand binding and functional data for mAChRs

HEK293T cells were transiently transfected in 24-well plates with 50 ng/well of M1, M3, or M5 mAChR plasmid DNA. Whole-cell saturation binding was measured with [3H]NMS and the KD and Bmax values were calculated. Whole-cell accumulation of [3H]InsPx was measured with increasing concentrations of carbachol, and the EC50 and Emax values were calculated. Results are the mean ± S.E. of three individual experiments performed in duplicate (functional assays) or triplicate (radioligand binding assays). Statistical comparisons were by one-way ANOVA followed by Bonferroni's post-test. The Emax values (counts per minute of radioactivity) obtained for the three receptors were not statistically different (P > 0.05).


mAChR

M1

M3

M5
KD (nM) 6 ± 0.4 17 ± 1a 6 ± 0.4
Bmax (×106 receptors/cell) 1.3 ± 0.13 3.6 ± 0.14b 1.3 ± 0.16
EC50 (nM) 593 ± 55 209 ± 71c 114 ± 24d
Emax (cpm)
3845 ± 162
2734 ± 529
3004 ± 512
  • a P < 0.001 versus M1 or M5.

  • b P < 0.001 versus M1 or M5.

  • c P < 0.05 versus M1.

  • d P < 0.01 versus M1.