Role of Potassium Channels in the GABA Inhibitory Action on the Cholinergic Response to Electrical Field Stimulation in Guinea-pig Ileum

Abstract

γ-Aminobutyric acid B (GABAB) receptor activation inhibits the cholinergic response to electrical field stimulation (EFS) in guinea-pig ileum. The involvement of potassium channels in this GABA inhibitory action was investigated. The modulatory effect of GABA was not modified after pre-incubation of the organ with 1 mM tetraethylammonium chloride, a non-selective potassium channel antagonist. Nevertheless, the non-selective K+ channels antagonists, 4-aminopyridine (3 mM) and quinine (200 μM), and the selective KATP channel antagonist glibenclamide (1 μM), significantly reduced the inhibitory effects of GABA. The results suggest a coupling between GABAB receptors and KATP channels in the guinea-pig ileum.