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  Calcium Dynamics associated with a single action potential in a CNS presynaptic terminal

Helmchen, F., Borst, J. G. G., & Sakmann, B. (1997). Calcium Dynamics associated with a single action potential in a CNS presynaptic terminal. Biophysical Journal, 72(3), 1458-1471. doi:10.1016/S0006-3495(97)78792-7.

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Genre: Journal Article
Alternative Title : Calcium Dynamics associated with a single action potential in a CNS presynaptic terminal

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Helmchen, Fritjof1, Author           
Borst, J. Gerard G.1, Author           
Sakmann, Bert1, Author           
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1Department of Cell Physiology, Max Planck Institute for Medical Research, Max Planck Society, ou_1497701              

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 Abstract: Calcium dynamics associated with a single action potential were studied quantitatively in the calyx of Held, a large presynaptic terminal in the rat brainstem. Terminals were loaded with different concentrations of high- or low-affinity CA2+ indicators via patch pipettes. Spatially averaged CA2+ signals were measured fluorometrically and analyzed on the basis of a single compartment model. A single action potential led to a total CA2+ influx of 0.8-1 pC. The accessible volume of the terminal was about 0.4 pl; thus the total calcium concentration increased by 10-13 microM. The Ca(2+)-binding ratio of the endogenous buffer was about 40, as estimated from the competition with Fura-2, indicating that 2.5% of the total calcium remained free. This is consistent with the peak increase in free calcium concentration of about 400 nM, which was measured directly with MagFura-2. The decay of the [CA2+]i transients was fast, with time constants of 100 ms at 23 degrees C and 45 ms at 35 degrees C, indicating CA2+ extrusion rates of 400 and 900 s-1, respectively. The combination of the relatively low endogenous Ca(2+)-binding ratio and the high rate of CA2+ extrusion provides an efficient mechanism for rapidly removing the large CA2+ load of the terminal evoked by an action potential

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Language(s): eng - English
 Dates: 1996-10-071996-12-121997-03-01
 Publication Status: Issued
 Pages: 14
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 Table of Contents: -
 Rev. Type: Peer
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Title: Biophysical Journal
  Other : Biophys. J.
Source Genre: Journal
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Publ. Info: Cambridge, Mass. : Cell Press
Pages: - Volume / Issue: 72 (3) Sequence Number: - Start / End Page: 1458 - 1471 Identifier: Other: 0006-3495
CoNE: https://pure.mpg.de/cone/journals/resource/954925385117