|
KMID : 0811720050090000062
|
|
Korean Journal of Physiology & Pharmacology
2005 Volume.9 No. 0 p.62 ~ p.0
|
|
|
Presynaptic Mitochondrial Calcium Buffering during Tetanic Stimulation Serves as a Main Source for Residual Calcium
|
|
Lee Do-Yun
Lee Kyu-Hee
Ho Won-Kyung
Lee Suk-Ho
|
|
|
Abstract
|
|
|
Recent studies on non-mammalian neurons suggest that the mitochondrial calcium uptake in response to the large elevation of [Ca2+]i and subsequent calcium release have several physiological roles including the build-up of residual calcium at presynaptic terminals. We studied how mitochondrial calcium transport influences [Ca2+]i dynamics in rat hippocampal mossy fiber boutons. When mitochondrial calcium uptake was inhibited by dissipating mitochondrial membrane potential with antimycin A1 or carbonyl cyanide m-chlorophenyl-hydazone, the tetanus-induced increase in [Ca2+]i was remarkably augmented. The mitochondrial calcium uniporter blocker, ruthenium red or Ru360, had similar effects, indicative of mitochondrial Ca2+-uptake. The inhibition of ER calcium uptake, however, did not alter the tetanus-induced increase in [Ca2+]i. The tetanus-induced increase in [Ca2+]i was followed by a period of elevated level of [Ca2+]i for several seconds, so-called residual calcium. The length of the residual calcium was proportionate to the frequency and the length of stimulation. When mitochondrial Ca2+ release was blocked by tetraphenylphosphonium (TPP+), the residual calcium was substantially attenuated. On the other hand, the treatment of TPP+ did not alter the calcium influx evoked by a single action potential, implying that TPP+ selectively attenuates calcium release from mitochondria after tetanus. The present study suggests mitochondria are the major calcium sequestration mechanism during tetanic stimulation in the mossy fiber boutons and the subsequent release of Ca2+ serves as a main source for residual calcium. This work was supported by Grant M103KV010012-03K2201-01220 from the Brain Research Center of the 21st Century Frontier Research Program and Grant for National Research Laboratory 2004-02433 from the Ministry of Science and Technology. D.L. and K.-H.L. were graduate students supported by Program BK21 from the Ministry of Education.
Source: Korean Journal of Physiology & Pharmacology.2005 Oct;9(Suppl I):S86-S86
|
|
|
KEYWORD
|
|
|
Mossy fiber boutons, Presynaptic, Calcium buffering, Mitochondria, Residual calcium
|
|
|
FullTexts / Linksout information
|
|
|
|
|
Listed journal information
|
|
  
|
|