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The Control of Fast and Slow Muscle Contractions in the Siphonophore Stem

  • G. O. Mackie

Abstract

The stem of the siphonophore Nanomia cara is the only coelenterate preparation so far found which allows intracellular recordings to be made both from muscles (Spencer, 1971) and nerves (Mackie, 1973); as such it offers unique possibilities for the analysis of neuro-muscular interactions at the cellular level. The stem muscle is also interesting as an example of an effector capable of responding by rapid, twitch-like contractions (both local and general) and also by slower, sustained contractions (Mackie, 196.+). Such muscles are found in all three classes of the Cnidaria (reviewed by Josephson, 1974) but the ways in which the two sorts of response (‘fast’ and’ slow’) are differentiated remains problematical. Only one histological type of muscle fibre seems to be involved; it is assumed that there are two excitation pathways. In sea anemones, the electrical correlates of fast contractions are known, but slow contractions can occur in the absence of recordable signals (McFarlane, 1973). In Nanomia, however, both fast and slow contractions have distinctive electrical correlates, the analysis of which is our present concern.

Keywords

Intracellular Recording Extracellular Recording Slow Muscle Giant Axon Sustained Contraction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Josephson, R.K. 1974. Cnidarian neurobiology. Ch. VI. in “Coelenterate Biology” (ed. L. Muscatine and H.M. Lenhoff) Academic Press.Google Scholar
  2. Mackie, G.O. 1964. Analysis of locomotion in a siphonophore colony. Proc. Roy. Soc. B, 159, 366–391.CrossRefGoogle Scholar
  3. Mackie, G.O. 1973. Report on giant nerve fibres in Nanomia. Publ. Seto Marine Lab. 20, 745–756.Google Scholar
  4. Mackie, G.O. and Passano, L.M. 1968. Epithelial conduction in Hydromedusae. J. Gen. Physiol. 52, 600–621.CrossRefGoogle Scholar
  5. McFarlane, I.D. 1973. Spontaneous contractions and nerve net activity in the sea anemone Calliactis parasitica. Mar. Behav. Physiol. 2, 97–113.CrossRefGoogle Scholar
  6. Spencer, A.N. 1971. Myoid conduction in the siphonophore Nanomia bijuga. Nature 233, 490–491.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1976

Authors and Affiliations

  • G. O. Mackie
    • 1
  1. 1.Biology DepartmentUniversity of VictoriaVictoriaCanada

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