TABLE 1 .

Analysis of Ca²⁺ and PIP2 responses to CCh and pilocarpine in M1R- and M3R-expressing cells

CHO-K1 or HEK293T cells were transfected with either M1R or M3R-expressing plasmids. Nontransfected HEK293 cells were used to study the endogenous M3R present in these cells. The EC₅₀ and E_max were determined for pilocarpine (Pilo) and CCh in two functional assays: free Ca²⁺ and PIP2 measurements. The experiments were performed as discussed in the text and in the Materials and Methods. Shown are means ± S.D. for the values determined in three to four independent experiments.

		CHO-K1				HEK293T
		Ca2+		PIP2		Ca2+		PIP2
		EC50	Emax	EC50	Emax	EC50	Emax	EC50	Emax
		μM	%	μM	%	μM	%	μM	%
Endogenous M3R	Pilo	n.a.	n.a.	n.a.	n.a.	—	0	—	0
	CCh	n.a.	n.a.	n.a.	n.a.	11 ± 2	44 ± 5	—	0
Transfected M3R	Pilo	0.19 ± 0.06	71 ± 6	—	0	n.d.	n.d.	—	0
	CCh	0.06 ± 0.02	100	4 ± 1	100	0.04 ± 0.01	100	4 ± 1	100
Transfected M1R	Pilo	0.21 ± 0.07	84 ± 7	2 ± 0.6	83 ± 8	n.d.	n.d.	n.d.	n.d.
	CCh	0.11 ± 0.04	100	1.2 ± 0.4	100	n.d.	n.d.	n.d.	n.d.

n.a., not applicable; n.d, not determined; —, no functional response was detected under these conditions.