Neuromuscular sensitivity to hydrogen sulfide in the marine invertebrate Urechis caupo

Hydrogen sulfide (HS) is a well-known inhibitor of aerobic respiration via its reversible binding of mitochondrial cytochrome c oxidase, but recent studies have suggested that HS may have other non-respiratory actions. We have studied the effects of HS on spontaneous and evoked contractions in vitro...

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Bibliographic Details
Published in:	Journal of experimental biology Vol. 201; no. Pt 9; pp. 1393 - 1403
Main Authors:	Julian, D, Dalia, W E, Arp, A J
Format:	Journal Article
Language:	English
Published:	England 01-05-1998
Subjects:	Animals Annelida - drug effects Annelida - physiology Electric Stimulation Hydrogen Sulfide - toxicity Muscle Contraction - drug effects Neuromuscular Junction - drug effects
Online Access:	Get full text
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Summary:	Hydrogen sulfide (HS) is a well-known inhibitor of aerobic respiration via its reversible binding of mitochondrial cytochrome c oxidase, but recent studies have suggested that HS may have other non-respiratory actions. We have studied the effects of HS on spontaneous and evoked contractions in vitro under hypoxic and anoxic conditions in nerve-muscle preparations from the echiuran worm Urechis caupo. Contraction amplitude in response to electric field stimulation under anoxic conditions was completely abolished by HS within minutes in a classic dose-response relationship (Kd=31 mmol l-1, r2=0.86). Exposure of body wall and esophagus to HS in vitro for up to 6 h demonstrated that the contraction amplitude and frequency of spontaneous activity were relatively insensitive to anoxia, but that the sensitivity to HS was similar to that seen in field-stimulated muscle (Kd=2.7-32 mmol l-1). The toxic effects of HS were reversible, with almost complete recovery under anoxic conditions within the first hour. These data indicate that HS at millimolar concentrations can directly inhibit muscle contraction. Although the mechanism of this action is unknown, it does not appear to involve metabolic pathways or oxygen transport.
ISSN:	0022-0949 1477-9145
DOI:	10.1242/jeb.201.9.1393