Abstract:
:A global and transient rise of intracellular Ca2+ (Ca2+i) is central to the operation of pump-leak coupling in the frog early distal tubule (EDT). The endoplasmic reticulum (ER) is the site of this Ca2+ release and reuptake; however, it is likely that other intracellular pools, such as mitochondria, also contribute to cellular Ca2+ homeostasis. The present study was performed to seek evidence of mitochondrial Ca2+ transport in the frog EDT. Experiments were performed on isolated and permeabilized EDT segments from the frog kidney loaded with the low-affinity, Ca2+-sensitive fluorescent indicator, mag-fura-2. Ca2+ uptake in the absence of SarcoEndoplasmic Reticulum Calcium ATPase (SERCA) activity (inhibition by 2,5-di-t-butyl hydroquinone, TBQ) was evident at a bath [Ca2+] of 1 microm, but not at 200 nm, in the presence of ATP. This uptake was sensitive to the protonophore FCCP and the ATP-synthase inhibitor oligomycin. Ca2+ uptake was also stimulated by respiratory substrates; this uptake was enhanced by oligomycin and reversed by the application of FCCP. These findings provide the first evidence of mitochondrial Ca2+ transport in renal tubules, which appears to occur via a low-affinity pathway and which will act as a physiological Ca2+ buffer, protecting the cell from large increases in Ca2+i.
journal_name
Exp Physioljournal_title
Experimental physiologyauthors
Fowler MR,Hunter Mdoi
10.1113/expphysiol.2004.028886subject
Has Abstractpub_date
2005-03-01 00:00:00pages
195-201issue
2eissn
0958-0670issn
1469-445Xpii
expphysiol.2004.028886journal_volume
90pub_type
杂志文章abstract::In Helix aspersa, activation of the cerebral giant serotonin neurones (GSNs) evokes a biphasic, excitatory synaptic response in the M neurones of the buccal ganglia. Local application of serotonin to the current-clamped M neurones also evokes fast and slow depolarizing responses. The slow response is thought to be dep...
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更新日期:2020-10-01 00:00:00
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更新日期:2021-01-01 00:00:00
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doi:10.1113/expphysiol.2006.036590
更新日期:2007-03-01 00:00:00
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更新日期:1992-11-01 00:00:00
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