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Table 7 Effects of alcuronium and gallamine on ACh-stimulated [35S]GTPγS binding at M3 receptors.

From: Divergence of allosteric effects of rapacuronium on binding and function of muscarinic receptors

 

40 nM [3H]ACh binding

[35S]GTPγS binding

 

kobs [min-1]

Beq [fmol/mg prot.]

kobs [min-1]

Beq [fmol/μg prot.]

pEC50

EMAX [fold over basal]

Control

1.28 ± 0.06

357 ± 17

0.0579 ± 0.0013

530 ± 37

5.18 ± 0.03

2.94 ± 0.12

+ 1 μM alcuronium

1.00 ± 0.02*

262 ± 10*

0. 0509 ± 0.0017*

496 ± 33

5.03 ± 0.02*

2.90 ± 0.14

+ 10 μM alcuronium

0.888 ± 0.012*

199 ± 12*

0.0481 ± 0.0021*

428 ± 39*

4.82 ± 0.02*

2.87 ± 0.12

+ 1 μM gallamine

1.06 ± 0.02*

246 ± 10*

0.0525 ± 0.0015*

479 ± 29

5.01 ± 0.04*

2.83 ± 0.12

+ 10 μM gallamine

0.783 ± 0.009*

191 ± 8*

0.0492 ± 0.0015*

442 ± 27*

4.82 ± 0.01*

2.73 ± 0.15

  1. Values of observed rates of association (kobs) and equilibrium binding (Beq) of 40 nM [3H]ACh with M3 receptors were obtained by fitting Eq. 6 to data in Figure 10 (top). Values of kobs and Beq of 200 pM [35S]GTPγS with M3 receptors were obtained by fitting Eq. 6 to data in Figure 10 (middle). Negative logarithms of half effective concentrations (pEC50) and maximum stimulatory effect (EMAX) of acetylcholine on [35S]GTPγS binding in the absence or presence of the indicated concentrations of alcuronium or gallamine were obtained by fitting Eq. 5 to the data in Figure 10 (bottom). Values are means ± SE of fits to 3 to 6 independent experiments performed in quadruplicates. *P < 0.05; significantly different from control (ACh alone) by ANOVA and Tukey-Kramer post-test.
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BMC Pharmacology

ISSN: 1471-2210