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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

Nguyen, Trung V and Matsuyama, Hayato and Baell, Jonathan and Hunne, Billie and Fowler, Christopher J and Smith, Julia E and Nurgali, Kulmira and Furness, John B (2007) Effects of compounds that influence IK (KCNN4) channels on afterhyperpolarizing potentials, and determination of IK channel sequence, in guinea pig enteric neurons. Journal of Neurophysiology, 97 (3). pp. 2024-2031. ISSN 002-23077

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Abstract

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 M) and clotrimazole (10 M), and was enhanced by the potentiator of the opening of these channels, DC-EBIO (100nM). 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.

Item Type: Article
Uncontrolled Keywords: ResPubID18851, guinea pigs, gastrointestinal tract, enteric nervous system
Subjects: FOR Classification > 0601 Biochemistry and Cell Biology
FOR Classification > 0707 Veterinary Sciences
Faculty/School/Research Centre/Department > School of Biomedical and Health Sciences
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Depositing User: VUIR
Date Deposited: 04 Aug 2011 03:06
Last Modified: 18 Jun 2015 02:10
URI: http://vuir.vu.edu.au/id/eprint/3373
DOI: 10.1152/jn.00935.2006
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Citations in Scopus: 16 - View on Scopus

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