Table 5.

Effects of carbachol on the kinetics of [³H]GDP binding to G_i/o and G_s/olf G-proteins

		Control	10 µM carbachol	100 µM carbachol
Gi/o	kobs1[min−1]	0.055 ± 0.003	0.0056 ± 0.0003**	0.0044 ± 0.0002**
	Beq1[fmol·µg−1 protein]	2.1 ± 0.2	1.7 ± 0.2**	0.35 ± 0.03**
	kobs2[min−1]	0.011 ± 0.006
	Beq2[fmol·µg−1 protein]	1.1 ± 0.1
	koff1[min−1]	0.35 ± 0.03	2.2 ± 0.2**	2.8 ± 0.3**
	koff2[min−1]	0.040 ± 0.004	0.26 ± 0.03**	0.32 ± 0.03**
	f2[%]	37 ± 5	38 ± 4	36 ± 5
Gs/olf	kobs[min−1]	0.031 ± 0.003	0.030 ± 0.003	0.031 ± 0.003
	Beq[fmol·µg−1 protein]	0.81 ± 0.04	0.43 ± 0.02**	0.10 ± 0.01**
	koff[min−1]	0.067 ± 0.007	0.12 ± 0.01**	0.20 ± 0.02**

Association rate constants (k_obs), equilibrium binding (B_eq), dissociation rate constants (k_off) and percentages (f₂) of populations were obtained by fitting Equations 6a and 6b or 7a and 7b as appropriate to data from individual experiments shown in Figure 9. Values from better fits are shown. Data are means ± SEM of values from three independent experiments performed in triplicates.

^**P < 0.01, significantly different from control in the absence of carbachol by t-test.

GDP, guanosine diphosphate.