Journal of comparative physiology

, Volume 114, Issue 1, pp 91–101 | Cite as

Comparative analysis of an excitatory motor unit in crustaceans

  • R. G. Sherman
Article

Summary

  1. 1.

    The leg stretcher muscle motor unit was examined in five different decapod crustaceans (Gecarcinus, Grapsus, Goniopsis, Homarus andPanulirus) with the objective of establishing interrelationships between nerve terminal and muscle fiber properties.

     
  2. 2.

    In each species, nerve terminals varied greatly in their capacity for facilitation of transmitter release (Fe), muscle fibers varied with respect to sarcomere length (SL), and a wide range of excitatory postsynaptic potential amplitudes (EPSPs) was observed.

     
  3. 3.

    Fe was inversely correlated with EPSP amplitude and SL in all five species. Therefore, selective matching of nerve terminals to muscle fibers appears to be a general rule of organization in the stretcher excitatory motor unit in decapod crustaceans.

     
  4. 4.

    A correlation was found between the Fe type of terminal and total depolarization of the sarcolemma at frequencies up to 20 Hz for all species. No such correlation was evident above 40 Hz for any species, indicating that all muscle fibers in the motor unit are activated to approximately the same extent at the higher levels of activity.

     
  5. 5.

    Possible consequences of these interrelationships for the performance of the motor unit are discussed.

     

Keywords

Muscle Fiber Comparative Analysis General Rule Motor Unit Nerve Terminal 

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References

  1. Atwood, H.L.: Differences in muscle fibre properties as a factor in “fast” and “slow” contraction inCarcinus. Comp. Biochem. Physiol.10, 17–32 (1963)Google Scholar
  2. Atwood, H.L.: Crustacean neuromuscular mechanisms. Amer. Zool.7, 527–551 (1967)Google Scholar
  3. Atwood, H.L.: An attempt to account for the diversity of crustacean muscles. Amer. Zool.13, 357–378 (1973)Google Scholar
  4. Atwood, H.L., Bittner, G.D.: Matching of excitatory and inhibitory inputs to crustacean muscle fibers. J. Neurophysiol.34, 157–170 (1971)Google Scholar
  5. Atwood, H.L., Dorai Raj, B.S.: Tension development and membrane responses in phasic and tonic muscle fibers of a crab. J. cell. comp. Physiol.64, 55–72 (1974)Google Scholar
  6. Bittner, G.D.: The differentiation of crayfish muscle fibers during development. J. exp. Zool.167, 439–456 (1968a)Google Scholar
  7. Bittner, G.D.: Differentiation of nerve terminals in the crayfish opener muscle and its functional significance. J. gen. Physiol.51, 731–748 (1968b)Google Scholar
  8. Frank, E.: Matching of facilitation at the neuromuscular junction of the lobster: a possible case for influence of muscle on nerve. J. Physiol. (Lond.)233, 635–658 (1973)Google Scholar
  9. Franzini-Armstrong, C.: Natural variability in the length of thin and thick filaments in single fibers from a crab,Portunus depurator. J. Cell Sci.6, 559–592 (1970)Google Scholar
  10. Jahromi, S.S., Atwood, H.L.: Correlation of structure, speed of contraction, and total tension in fast and slow abdominal muscles of the lobster (Homarus americanus). J. exp. Zool.171, 25–38 (1969)Google Scholar
  11. Jahromi, S.S., Atwood, H.L.: Structural and contractile properties of lobster leg-muscle fibers. J. exp. Zool.176, 475–486 (1971)Google Scholar
  12. Ozeki, M.: Crayfish muscle fiber: Spike electrogenesis in fibers with long sarcomeres. Science163, 82–83 (1969)Google Scholar
  13. Sherman, R.G., Atwood, H.L.: Correlated electrophysiological and ultrastructural studies of a crustacean motor unit. J. gen. Physiol.59, 586–615 (1972)Google Scholar
  14. Snedecor, G.W., Cochran, W.G.: Statistical Methods. 6th edit. Ames, Iowa: The Iowa State Univ. Press 1967Google Scholar
  15. Spirito, C.P.: Reflex control of the opener and stretcher muscles in the cheliped of the fiddler crab,Uca pugnax. Z. vergl. Physiol.68, 211–228 (1970)Google Scholar
  16. Wheal, H.V., Kerkut, G.A.: Electrophysiological and morphological investigations of the neuromuscular junction of the hermit crab,Eupagurus bernhardus. Comp. Biochem. Physiol.54A, 13–18 (1976)Google Scholar

Copyright information

© Springer-Verlag 1977

Authors and Affiliations

  • R. G. Sherman
    • 1
  1. 1.Department of BiologyClark UniversityWorcesterUSA

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