TABLE 1

Parameters describing the functional interaction between the orthosteric antagonists atropine or pirenzepine and the agonist carbachol at M1 mAChRs expressed in CHO cells Values are the mean ± S.E.M. of three to four independent experiments. pKB is the negative logarithm of the antagonist dissociation constant. pKB and Schild slope are estimated by nonlinear regression according to eq. 1 under Materials and Methods.

Parameter Orthosteric Antagonist
Atropine Pirenzepine
IP accumulation
   pKB 9.61 ± 0.05 8.05 ± 0.02
   Schild slope 1.13 ± 0.05 1.04 ± 0.01
Calcium mobilization
   pKB 9.66 ± 0.06 8.13 ± 0.04
   Schild slope 1.00 ± 0.01 0.94 ± 0.03