Agonist pharmacology of the neuronal alpha 7 nicotinic receptor expressed in Xenopus oocytes.
The potencies and efficacies of seven agonists at chick alpha 7 nicotinic receptors expressed in Xenopus oocytes were determined by whole cell recording. (+)-Anatoxin-a was the most potent agonist (EC50 = 0.58 microM) and acetylcholine was the least potent (EC50 = 320 microM). The rank order of agonist potencies was: (+)-anatoxin-a >> cytisine > (-)-nicotine > (+)-nicotine > DMPP > 1-acetyl-4-methylpiperazine methiodide > acetylcholine. DMPP evoked only very small currents: comparison of maximally effective agonist concentrations showed that DMPP was only one-fifth as efficacious as other agonists. Previously published IC50 values for rat brain [125I]alpha-bungarotoxin sites show a similar agonist profile, and the identity of homo-oligomeric alpha 7 receptors with native alpha-bungarotoxin-sensitive neuronal nicotinic receptors is discussed.
Amar
M
M
Department of Biochemistry, University of Bath, UK.
Thomas
P
P
Johnson
C
C
Lunt
G G
GG
Wonnacott
S
S
D000109:Acetylcholine / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001392:Azocines; D001427:Bacterial Toxins / Q000494:pharmacology; D000087522:Cyanobacteria Toxins; D004247:DNA; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D008387:Marine Toxins / Q000494:pharmacology; D008564:Membrane Potentials; D052998:Microcystins; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D009538:Nicotine / Q000494:pharmacology; D009865:Oocytes; D010879:Piperazines / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds; D011807:Quinolizines; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000235:genetics; D014326:Tropanes; D014981:Xenopus; D000093843:Quinolizidine Alkaloids
D000109:Acetylcholine; D000470:Alkaloids; D001392:Azocines; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D004247:DNA; D004246:Dimethylphenylpiperazinium Iodide; D008387:Marine Toxins; D052998:Microcystins; D009538:Nicotine; D010879:Piperazines; D000644:Quaternary Ammonium Compounds; D011807:Quinolizines; D011978:Receptors, Nicotinic; D014326:Tropanes; C004712:cytisine; D000093843:Quinolizidine Alkaloids; C080419:1,1-dimethyl-4-acetylpiperazinium; C509783:anatoxin a