A New Gregarine from Urechis caupo

1938 ◽  
Vol 57 (2) ◽  
pp. 142 ◽  
Author(s):  
Elmer R. Noble
Keyword(s):  
Urechis Caupo

Neuromuscular sensitivity to hydrogen sulfide in the marine invertebrate Urechis caupo.

1998 ◽  
Vol 201 (9) ◽  
pp. 1393-1403
Author(s):  
D Julian ◽  
W E Dalia ◽  
A J Arp
Keyword(s):  
Hydrogen Sulfide ◽  
Marine Invertebrate ◽  
Complete Recovery ◽  
Reversible Binding ◽  
Contraction Amplitude ◽  
Anoxic Conditions ◽  
Urechis Caupo ◽  
Nerve Muscle ◽  
Evoked Contractions

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.

Neuromuscular Mechanisms of Burrow Irrigation in the Echiuroid Worm Urechis Caupo Fisher & Macginitie

1966 ◽  
Vol 45 (2) ◽  
pp. 343-356
Author(s):  
JAMES V. LAWRY
Keyword(s):  
Constant Temperature ◽  
Nervous Systems ◽  
Urechis Caupo

1. The anatomy of the muscular and nervous systems of Urechis is described. 2. An apparatus is described whereby it is possible to record the parameters of the peristaltic waves used in irrigating the tube. 3. Urechis is continuously active and shows no periodicity under conditions of constant temperature. About 1280 peristaltic waves are initiated, and about 29 l. of water are moved, in 24 hr.

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