Journal of Comparative Physiology A

, Volume 155, Issue 2, pp 197–208 | Cite as

Ionic bases of action potentials in identified flatworm neurones

  • Larry Keenan
  • Harold Koopowitz


The ionic bases for generation of action potentials in three types of identified multimodal neurones of the brain ofNotoplana acticola, a polyclad flatworm, were studied. The action potentials were generated spontaneously, in response to water-borne vibrations, or by intracellularly injected current pulses. At least three components comprise the depolarizing excitable phase of the action potentials: (a) a rapidly inactivating TTXsensitive Na+ component (Fig. 2); (b) a Ca++ component that is unmasked by intracellular TEA+ (Figs. 4, 6, 7); (c) a TTX-resistant Na+ component (Fig. 8). Two K+ currents appear to account for the repolarization phase of the action potentials: (a) a rapid K+ current that is blocked by intracellular TEA+ (Figs. 4, 7, 8) and (b) a Ca++ -activated K+ conductance that is blocked by Ca++ and Ba++ (Fig. 6). Ionic mechanisms in the generation of action potentials in the central multimodal neurones ofNotoplana pharmacologically resemble those in higher metazoans.


Current Pulse Ionic Mechanism Ionic Base Repolarization Phase Excitable Phase 
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.





tetraethylammonium ion


lucifer yellow


horseradish peroxidase


bilaterally reciprocally arrayed neurons


single contralaterally projecting


single ipsilaterally and contralaterally projecting neurons


hyperpolarizing after potential


after hyperpolarization


ethyleneglycol-bis-(β-amino-ethyl ester) N,N′-tetra-acetic acid


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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Larry Keenan
    • 1
  • Harold Koopowitz
    • 1
  1. 1.Developmental and Cell Biology DepartmentUniversity of CaliforniaIrvineUSA

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