Bicuculline blocks nicotinic acetylcholine response in isolated intermediate lobe cells of the pig.
1. The effect of bicuculline on nicotinic acetylcholine (ACh) responses in isolated intermediate lobe (IL) cells of the pig was investigated by use of patch-clamp techniques. Bicuculline was found to reduce ACh-evoked whole-cell currents (IACh) in all cells tested (n = 40). 2. The blocking effect of bicuculline on IACh was dose-dependent, the concentration producing half-maximal blockade being 43.8 microM. 3. The blockade of IACh by bicuculline was not voltage-dependent at membrane potentials above -60 mV, but a slight voltage-dependence was observed at holding potentials (HP) of -80 and -100 mV. 4. The inhibitory effect of bicuculline on IACh was partially competitive at a HP of -60 mV. 5. Neither SR 95531, a pyridazinyl gamma-aminobutyric acid derivative, nor t-butylbicyclophosphorothionate (TBPS) blocked IACh in IL cells. 6. It is concluded that bicuculline interacts directly with the ACh receptor-ionophore complex on porcine IL cells.
Zhang
Z W
ZW
Institut de Physiologie (UA309 CNRS), Université Louis Pasteur, Strasbourg, France.
Feltz
P
P
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018756:GABA Antagonists; D066298:In Vitro Techniques; D007539:Isonicotinic Acids / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D011724:Pyridazines / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects*; D012996:Solutions; D013552:Swine
D001643:Bridged Bicyclo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018756:GABA Antagonists; D007539:Isonicotinic Acids; D011724:Pyridazines; D011978:Receptors, Nicotinic; D012996:Solutions; C037476:tert-butylbicyclophosphorothionate; C049853:gabazine; D001640:Bicuculline; C015300:isoguvacine