TY - JOUR T1 - Histamine Suppresses A-Type Potassium Current in Myenteric Neurons from Guinea Pig Small Intestine JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 555 LP - 561 VL - 294 IS - 2 AU - Alexander M. Starodub AU - Jackie D. Wood Y1 - 2000/08/01 UR - http://jpet.aspetjournals.org/content/294/2/555.abstract N2 - Perforated patch-clamp methods for recording ionic currents in the whole-cell configuration were used to test the hypothesis that the ionic mechanisms for the excitatory actions of histamine on enteric neurons include suppression of A-type K+ current (IA). Histamine and the selective histamine H2 receptor agonist, dimaprit, reduced the amplitude ofIA without affecting the slope factor forIA steady-state inactivation curves. Suppression of IA was restricted to after hyperpolarization-type myenteric neurons that were immunoreactive for calbindin. The selective histamine H2 receptor antagonist cimetidine suppressed the action of histamine and dimaprit. Elevation of intraneuronal cAMP by forskolin, a membrane-permeant analog of cAMP, and treatment with a phosphodiesterase inhibitor suppressedIA. The results are consistent with the hypothesis that suppression of IA is part of the ionic mechanism responsible for elevation of excitability during both slow synaptic excitation and slow synaptic excitation-like responses evoked by paracrine mediators, such as histamine, in after hyperpolarization-type myenteric neurons. The American Society for Pharmacology and Experimental Therapeutics ER -