(±)α-Phenyl-β-(3,4-dimethoxy)- and (±)α-Phenyl-β-(3,4-dihydroxy)phenethylamines: Potential Probes for Nicotinic Acetylcholine Receptor-Ion Channel Molecule from Torpedo Electric Organ

1987 ◽  
Vol 76 (10) ◽  
pp. 830-833
Author(s):  
Ragab M. Shafik ◽  
Raafat Soliman ◽  
Soad A. El-Hawash ◽  
Samia A. El-Dardiry ◽  
Shebl Sherby
Keyword(s):  
Ion Channel ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Electric Organ ◽  
Nicotinic Acetylcholine ◽  
Torpedo Electric Organ

scholarly journals Synthesis of an antigenic site of native acetylcholine receptor peptide 159-169 of Torpedo acetylcholine receptor α-chain

1985 ◽  
Vol 226 (1) ◽  
pp. 193-197 ◽  
Author(s):  
D J McCormick ◽  
V A Lennon ◽  
M Z Atassi
Keyword(s):  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Antigenic Site ◽  
Electric Organ ◽  
Alpha Subunit ◽  
Nicotinic Acetylcholine ◽  
Antigenic Region ◽  
Torpedo Electric Organ ◽  
Α Chain ◽  
Immobilized Peptide

A region of the alpha-subunit of the nicotinic acetylcholine receptor (AChR) of the Torpedo electric organ, containing residues 161-166, has been proposed to be a major antigenic site in the native AChR protein. We report the synthesis of a peptide corresponding to residues 159-169, which contains the proposed antigenic region. In quantitative radiometric titrations, radiolabelled anti-(native AChR) antibodies from three different species, rabbit, rat and dog, exhibited considerable binding (approx. 15% relative to native AChR) to Sepharose-immobilized peptide 159-169, but did not bind significantly to Sepharose-immobilized unrelated proteins or peptides. Specificity was further confirmed by the finding that no rabbit anti-AChR antibodies bound to the peptide after absorption with native AChR. These data indicate that the region 159-169 contains an antigenic site that is readily accessible in solubilized native Torpedo AChR.

scholarly journals Effects of Bis(7)-Tacrine on Spontaneous Synaptic Activity and on the Nicotinic ACh Receptor of Torpedo Electric Organ

2001 ◽  
Vol 86 (1) ◽  
pp. 183-189 ◽  
Author(s):  
Esteve Ros ◽  
Jordi Aleu ◽  
Inmaculada Gomez De Aranda ◽  
Carles Cantí ◽  
Yuan-Ping Pang ◽  
...  
Keyword(s):  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Electric Organ ◽  
Synaptic Activity ◽  
Hill Coefficient ◽  
Nicotinic Acetylcholine ◽  
Torpedo Electric Organ ◽  
Induced Currents

Bis(7)-tacrine is a potent acetylcholinesterase inhibitor in which two tacrine molecules are linked by a heptylene chain. We tested the effects of bis(7)-tacrine on the spontaneous synaptic activity. Miniature endplate potentials (MEPPs) were recorded extracellularly on slices of electric organ of Torpedo marmorata. Bis(7)-tacrine, at a concentration of 100 nM, increased the magnitudes that describe MEPPs: amplitude, area, rise time, rate of rise, and half-width. We also tested the effect of bis(7)-tacrine on nicotinic acetylcholine receptors by analyzing the currents elicited by acetylcholine (100 μM) in Torpedo electric organ membranes transplanted in Xenopus laevis oocytes. Bis(7)-tacrine inhibited the acetylcholine-induced currents in a reversible manner (IC50 = 162 nM). The inhibition of nicotinic acetylcholine receptors was not voltage dependent, and bis(7)-tacrine increased the desensitization of nicotinic acetylcholine receptors. The Hill coefficient for bis(7)-tacrine was −0.72 ± 0.02, indicating that bis(7)-tacrine binds to the nicotinic acetylcholine receptor in a molecular ratio of 1:1, but does not affect the binding of α-bungarotoxin with the nicotinic acetylcholine receptor. In conclusion, bis(7)-tacrine greatly increases the spontaneous quantal release from peripheral cholinergic terminals at a much lower concentration than tacrine. Bis(7)-tacrine also blocks acetylcholine-induced currents of Torpedo electric organ, although the mechanism is different from that of tacrine: bis(7)-tacrine enhances desensitization, whereas tacrine reduces it.

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