Journal of Comparative Physiology A

, Volume 198, Issue 6, pp 477–483

Calcium buffering and clearance in spider mechanosensory neurons

  • Joscha Schmitz
  • Ulli Höger
  • Päivi H. Torkkeli
  • Andrew S. French
Short Communication

Abstract

Spider VS-3 mechanoreceptor neurons have a low-voltage-activated Ca2+ current that raises intracellular calcium concentration [Ca2+] when they are depolarized by agonists of GABAA receptors or fire action potentials. The Ca2+ rise produces negative feedback by modulating the mechanoreceptor current and regulates Ca2+- and voltage-activated K+ currents. However, nothing is known about Ca2+ buffering in VS-3 neurons. Dynamic changes in VS-3 neuron intracellular [Ca2+] were measured using the fluorescent Ca2+ indicator Oregon Green BAPTA-1 (OG488) to understand Ca2+ buffering and clearance. Intracellular OG488 concentration increased slowly over more than 2 h as it diffused through a sharp intracellular microelectrode and spread through the cell. This slow increase was used to measure endogenous Ca2+ buffering and clearance by the added buffer technique, with OG488 acting as both added exogenous buffer and Ca2+ indicator. [Ca2+] was raised for brief periods by regular action potential firing, produced by pulsed electric current injection through the microelectrode. The resulting rise and fall of [Ca2+] were well fitted by the single compartment model of Ca2+ dynamics. With earlier ratiometric [Ca2+] estimates, these data gave an endogenous Ca2+ binding ratio of 684. Strong Ca2+ buffering may assist these neurons to deal with rapid changes in mechanical inputs.

Keywords

Cupiennius salei Mechanosensory Fluorescence Single compartment Calcium indicator 

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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Joscha Schmitz
    • 1
  • Ulli Höger
    • 1
  • Päivi H. Torkkeli
    • 1
  • Andrew S. French
    • 1
  1. 1.Department of Physiology and BiophysicsDalhousie UniversityHalifaxCanada

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