Ca2+ dynamics at the frog motor nerve terminal

Shin ichi Suzuki, Makoto Osanai, Masaki Murase, Naoya Suzuki, Koumin Ito, Tetsuya Shirasaki, Kazuhiko Narita, Kiyoshi Ohnuma, Kenji Kuba, Hiromasa Kijima

研究成果: Article査読

34 被引用数 (Scopus)

抄録

Rises in free [Ca2+](i) in response to various tetanic stimuli (Ca2+ transient) in frog motor nerve terminals were measured by recording fluorescence changes of Ca2+ indicators and analyzed in relation to short- term synaptic plasticity. Ca2+ transients reached a plateau after 10-20 impulses at 100 Hz and decayed in a three-exponential manner, in which the fast component was predominant. The plateau and fast component of the Ca2+ transient were elevated infralinearly with an increase in tetanus frequency. Computer simulation showed that the Ca2+ transients estimated from fluorescence changes faithfully reflect the true changes in [Ca2+](i) except for the initial 20 ms. A slow Ca2+ chelator, EGTA, loaded into the nerve terminal, decreased the magnitude of both the fast and slow components of facilitation of transmitter release and the time constant of the former. A fast Ca2+ chelator, BAPTA, decreased the magnitude of fast facilitation but slightly increased its time constant. These results suggest that Ca2+ transients in the frog motor nerve terminals are primarily caused by Ca2+ entry and are dissipated by three components, in which the rate of the fast component is equivalent to that of free Ca2+ diffusion. The residual Ca2+ in the nerve terminals after stimulation accounts for the fast component of facilitation.

本文言語English
ページ(範囲)351-365
ページ数15
ジャーナルPflugers Archiv European Journal of Physiology
440
3
DOI
出版ステータスPublished - 2000

ASJC Scopus subject areas

  • 生理学
  • 臨床生化学
  • 生理学(医学)

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