An analysis of inhibitory junction potentials in the guinea-pig proximal colon
Date
2004
Authors
Hirst, George
Bywater, R
Teramoto, Noriyoshi
Edwards, Frank
Journal Title
Journal ISSN
Volume Title
Publisher
Cambridge University Press
Abstract
Intracellular recordings were made from either sheets or isolated bundles of the circular muscle layer of guinea-pig proximal colon and the responses evoked by stimulating inhibitory nerve fibres were analysed. Inhibitory junction potentials (IJPs), evoked by single stimuli, had two components which could be separated on their pharmacological and temporal characteristics and their voltage sensitivities. The initial component, which was abolished by apamin and reduced in amplitude by pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS , had a brief time course: its amplitude was changed when the external concentration of potassium ions ([K+]o) was changed. The second component of the IJP had a slower onset than the first component, was abolished by L-nitroarginine (NOLA) and oxadiazolo quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase: its amplitude was little affected by changing [K+]o and was increased when the membrane potential of the circular layer was hyperpolarized. The observations suggest that the initial component of the IJP results from the release of ATP which triggers an increase in membrane conductance to K+ and that the second component results from the release of nitric oxide which suppresses a background inward current.
Description
Keywords
Keywords: 1h 1,2,4 oxadiazolo[4,3 a]quinoxalin 1 one; adenosine triphosphate; apamin; guanylate cyclase; n(g) nitroarginine; nitric oxide; potassium ion; pyridoxal phosphate 6 azophenyl 2',4' disulfonic acid; amplitude modulation; animal cell; animal tissue; articl
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Source
Journal of Physiology
Type
Journal article