Table 2 Selectivity of sigma-1 receptor ligands for the sigma-1 receptor (σ-1 R) over the muscarinic acetylcholine receptor (mACh R).

From: Simple ammonium salts acting on sigma-1 receptors yield potential treatments for cancer and depression

Compound

σ -1 R affinity

pKi ± SEM (n)

σ -1 R affinity

Ki (µM)

mACh R affinity pKi ± SEM (n)

mACh R affinity Ki (µM)

mACh R Ki/σ-1 R Ki

Atropine

4.5 ± 0.4 (4)

31

9.4 ± 0.3 (4)

0.0004

0.000012

Rimcazole

6.2 ± 0.2 (7)

0.60

4.49 ± 0.10 (7)

32

53

Dipentyl

ammonium

7.4 ± 0.5 (6)

0.043

3.4 ± 0.2 (5)

380

8840

Tripentyl

ammonium

7.8 ± 0.2 (6)

0.015

4.3 ± 0.4 (4)

47

3130

Bis(2-ethylhexyl)

ammonium

4.5 ± 0.3* (5)

29

3.9 ± 0.2 (6)

120

4.1

Triisopentyl

ammonium

4.1 ± 0.4* (6)

79

3.60 ± 0.11 (5)

251

3.4

  1. Affinities for the sigma-1 and muscarinic acetylcholine receptors (σ-1 R and mACh R, respectively) are shown as pKi and Ki values from competition binding assays. mACh R Ki/σ-1 R Ki shows the ratio between Ki values. These data are reproduced from the PhD thesis by J.M. Brimson44.
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