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Journal of comparative physiology

, Volume 141, Issue 3, pp 319–326 | Cite as

Calcium distribution and transport in myelinated nerve

  • F. P. J. Diecke
  • Marguerite A. Stout
Article

Summary

Ca in desheathed trunks of sciatic nerve ofRana pipiens is completely exchangeable with radioactive45Ca.45Ca distributes in three compartments, one intracellular compartment and two extracellular compartments, which exchange Ca with greatly different rate coefficients. Using impermeable solutes (sucrose, inulin, SO4) and electron microprobe techniques, we have identified the rapidly exchanging extracellular compartment as the interstitial space and the slowly exchanging extracellular compartment, accessible to solutes up to a molecular weight of 5,500, as the mesaxonal gap in the myelin sheath. Ca exists in both extracellular compartments as free Ca and in bound form. After equilibration in solutions containing 1 mM Ca, the contents of the extracellular compartments in mmole/kg wet weight are: 1) Interstitial space: free Ca=0.52, bound Ca=0.19; 2) Myelin region: free Ca=0.12, bound Ca 0.27. The intracellular space contains 0.11 mmole/kg wet weight of Ca. After 4 h of washout,45Ca release represents the Ca flux from the intracellular compartment since it can be inhibited 95% by the combined action of Na and Ca removal and the addition of La. Our results suggest further that45Ca release after this time represents a close approximation of the Ca transport across the axolemmal membrane.45Ca, therefore, represents a suitable tracer probe to investigate Ca compartmentalization and Ca exchange in this tissue.

Keywords

Sciatic Nerve Inulin Interstitial Space Myelin Sheath Intracellular Compartment 
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.

Abbreviations

NR

Normal Ringer

SE

standadard error

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Copyright information

© Springer-Verlag 1981

Authors and Affiliations

  • F. P. J. Diecke
    • 1
  • Marguerite A. Stout
    • 1
  1. 1.Department of PhysiologyCMDNJ-New Jersey Medical SchoolNewarkUSA

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