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Effects of Compounds That Influence IK (KCNN4) Channels on Afterhyperpolarizing Potentials, and Determination of IK Channel Sequence, in Guinea Pig Enteric Neurons

journal contribution
posted on 2024-08-20, 05:52 authored by Trung V Nguyen, Hayato Matsuyama, Jonathan Baell, Billie Hunne, Christopher J Fowler, Julia E Smith, Kulmira Nurgali, John Furness
The late afterhyperpolarizing potential (AHP) that follows the action potential in intrinsic primary afferent neurons of the gastrointestinal tract has a profound influence on their firing patterns. There has been uncertainty about the identity of the channels that carry the late AHP current, especially in guinea pigs, where the majority of the physiological studies have been made. In the present work, the late AHP was recorded with intracellular microelectrodes from myenteric neurons in the guinea pig small intestine. mRNA was extracted from the ganglia to determine the identity of the guinea pig intermediate conductance potassium ( IK) channel gene transcript. The late AHP was inhibited by two blockers of IK channels, TRAM34 (0.1–1 μM) and clotrimazole (10 μM), and was enhanced by the potentiator of the opening of these channels, DC-EBIO (100 nM). Action potential characteristics were unchanged by TRAM34 or DC-EBIO. The full sequence of the gene transcript and the deduced amino acid sequence were determined from extracts including myenteric ganglia and from bladder urothelium, which is a rich source of IK channel mRNA. This showed that the guinea pig sequence has a high degree of homology with other mammalian sequences but that the guinea pig channel lacks a phosphorylation site that was thought to be critical for channel regulation. It is concluded that the channels that carry the current of the late afterhyperpolarizing potential in guinea pig enteric neurons are IK channels.

History

Journal

Journal of Neurophysiology

Volume

97

Pagination

2024-2031

Location

United States

ISSN

0022-3077

eISSN

1522-1598

Language

en

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

3

Publisher

American Physiological Society