γ-Aminobutyric acid (GABA, half-maximal inhibitory concentration, IC50 = 9.9 μM) and (-)-baclofen (IC50 = 4.5 μM) but not 10-4 M muscimol, exerted a presynaptic inhibitory effect on cholinergic transmission in field-stimulated guinea-pig taenia coli preparations, in vitro. The antagonism by 10-5 M (1S, 9R)-bicuculline methiodide was not specific for GABA agonists. The results suggest that the GABA receptors involved were of type B.
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience