Document Detail

Separate sodium and calcium spikes in the same axon.
MedLine Citation:
PMID:  2858055     Owner:  NLM     Status:  MEDLINE    
Aglantha digitale is a jellyfish (order Hydromedusae) capable of two distinct kinds of locomotion; 'slow' swimming which is generated endogenously and is used in fishing behaviour, and 'fast' swimming which is evoked by predators and serves for escape. Both forms of swimming are produced by contraction of the bell-shaped body wall and expulsion of a jet of water from an opening at the base of the animal. During slow swimming, the contractions are weak and the animal moves about 15 mm, roughly one body length, but during a fast swim there is a more violent contraction which can propel the animal five times as far. Both forms of contraction depend on impulses in the eight giant motor axons that synapse directly with the muscle sheet making up the inner surface of the body wall. We report here that the giant motor axons are able to mediate both kinds of activity because they can conduct two different sorts of impulse. Fast swimming requires a rapidly conducted Na+-dependent action potential whereas slow swimming depends on a low amplitude Ca2+ 'spike'. This is the first report of an axon capable of two kinds of impulse propagation and it provides a physiological function for low potential Ca2+ activation.
G O Mackie; R W Meech
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Nature     Volume:  313     ISSN:  0028-0836     ISO Abbreviation:  Nature     Publication Date:    1985 Feb 28-Mar 6
Date Detail:
Created Date:  1985-04-18     Completed Date:  1985-04-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  791-3     Citation Subset:  IM    
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MeSH Terms
Action Potentials*
Axons / physiology
Calcium / physiology*
Cnidaria / physiology*
Motor Neurons / physiology*
Scyphozoa / anatomy & histology,  physiology*
Sodium / physiology*
Reg. No./Substance:
7440-23-5/Sodium; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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