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Pflügers Archiv

, Volume 434, Issue 4, pp 406–412 | Cite as

P/Q-type calcium channels activate neighboring calcium-dependent potassium channels in mouse motor nerve terminals

  • Dario A. Protti
  • Osvaldo D. Uchitel
ORIGINAL ARTICLE

Abstract

 The identity of the voltage-dependent calcium channels (VDCC), which trigger the Ca2+-gated K+ currents (IK(Ca)) in mammalian motor nerve terminals, was investigated by means of perineurial recordings. The effects of Ca2+ chelators with different binding kinetics on the activation of IK(Ca) were also examined. The calcium channel blockers of the P/Q family, ω-agatoxin IVA (ω-Aga-IVA) and funnel-web spider toxin (FTX), have been shown to exert a strong blocking effect on IK(Ca). In contrast, nitrendipine and ω-conotoxin GVIA (ω-CgTx) did not affect the Ca2+-activated K+ currents. The intracellular action of the fast Ca2+ buffers BAPTA and DM-BAPTA prevented the activation of the IK(Ca), while the slow Ca2+ buffer EGTA was ineffective at blocking it. These data indicate that P/Q-type VDCC mediate the Ca2+ influx which activates IK(Ca). The spatial association between Ca2+ and Ca2+-gated K+ channels is discussed, on the basis of the differential effects of the fast and slow Ca2+ chelators.

Key words Neuromuscular junction Synaptic transmission Calcium buffers ω-Agatoxin IVA FTX Calcium channels toxins 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Dario A. Protti
    • 1
  • Osvaldo D. Uchitel
    • 1
  1. 1.Instituto de Biología Celular y Neurociencias: ”Pr. Dr. Eduardo P. de Robertis”, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires (1121), ArgentinaAR

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