Physiological Basis of Earthworm Ventral Nerve Cord I. Heterogeneity of Cellular Mechanisms Underlying Calcium Mobilization in the Median Giant Fiber
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- Ogawa Hiroto
- Kawachi Millibioflight Project, ERATO, JST
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- Oka Kotaro
- Department of System Design Engineering, Faculty of Science and Technology, Keio University
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説明
We examined the spatio-temporal pattern of changes in intracellular Ca2+ concentration, [Ca2+li, in a median giant fiber (MGF) of the ventral nerve cord of the earthworm using confocal laser-scanning microscopy and fluorescent Ca2+ indicator. We found that the spatial distribution of [Ca2+li in unstimulated conditions was heterogeneous along the longitudinal axis of the MGF. Heterogeneity of the resting Ca2+ levels, therefore, may be the state of the MGF. Tetanic electrical stimulation of the ventral nerve cord evoked heterogeneous Ca2+ increases in the MGF. Depolarization by bath-application of high-K+ (62.5 mM) induced the transient and localized elevation of [Ca2+]i in the MGF. These Ca2+ rises were inhibited by a mixture of putative nonselective voltage-dependent Ca2+ channel (VDCC) blockers (Co2+, Ni2+ and Cd2+). Bath-application of caffeine (1 mM), which could activate the Ca2+-induced Ca2+-release (CICR), increased [Ca2+li all over the MGF. However, time-course analysis of the caffeineinduced response indicated that the Ca2+-rising velocities and the sustained Ca2+ levels were varied in cellular areas of the MGF. These results suggest that the VDCCs are localized on the plasma membrane of the MGF, while the ryanodine receptors mediating CICR are homogeneously distributed over the MGF.
収録刊行物
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- bioimages
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bioimages 4 (4), 137-147, 1996
日本バイオイメージング学会
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詳細情報 詳細情報について
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- CRID
- 1390852282341286912
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- NII論文ID
- 10002037912
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- NII書誌ID
- AA11084187
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- ISSN
- 09192719
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可
