Cellular and Molecular Neurobiology

, Volume 4, Issue 4, pp 319–338 | Cite as

Alteration of calcium conductances and outward current by cyclic adenosine monophosphate (cAMP) in neurons ofLimax maximus

  • Philip Hockberger
  • John A. Connor


  1. 1.

    Membrane responses to cyclic adenosine monophosphate (cAMP) injections have been studied by means of voltage clamp, Ca-indicator dye, and ion substitution techniques in identified neurons from the abdominal ganglion ofLimax maximus.

  2. 2.

    The ventral abdominal giant cell (AGC) displayed a response consisting of a decrease in outward current usually accompanied by a smaller enhancement of voltage-gated Ca2+ influx. Both responses were eliminated by external Cd2+ or Mn2+ and required membrane voltages more positive than −40 mV for expression. The enhanced influx persisted in Ba2+-substituted saline, while the decrease in outward current was blocked.

  3. 3.

    A group of dorsal neurons (RD1-3, LD1) showed a mixed Na-Ca influx induced by cAMP that could be activated over a wide range of membrane potentials (< − 100 to > − 20 mV). This flux caused a measurable increase in internal Ca2+. The influx was insensitive to Cd2+ and Mn2+ but was reduced by prolonged exposure to Co2+.

  4. 4.

    The relative magnitude of the Na-Ca flux ratio showed considerable variation between specimens. In immature animals the Ca component was absent.

  5. 5.

    The results demonstrated that elevation of intracellular cAMP can cause cell-specific changes of membrane conductance within closely associated neurons.


Key words

gastropod neurons cyclic adenosine monophosphate (cAMP) membrane conductance calcium voltage clamp arsenazo III 


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Copyright information

© Plenum Publishing Corporation 1984

Authors and Affiliations

  • Philip Hockberger
    • 1
    • 2
  • John A. Connor
    • 1
    • 2
  1. 1.Department of Molecular BiophysicsAT&T Bell LaboratoriesMurray HillUSA
  2. 2.Department of Physiology and BiophysicsUniversity of IllinoisUrbanaUSA

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