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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2319

Title: Ca2+ uptake in mitochondria occurs via the reverse action of the Na+/Ca2+ exchanger in metabolically inhibited MDCK cells
Authors: SMETS, Ilse
CAPLANUSI, Adrian
Despa, S
MOLNAR, Zsolt
RADU, Mihai
VAN DE VEN, Martin
AMELOOT, Marcel
STEELS, Paul
Issue Date: 2004
Publisher: AMER PHYSIOLOGICAL SOC
Citation: AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY, 286(4). p. F784-F794
Abstract: In ischemic or hypoxic tissues, elevated Ca2+ levels have emerged as one of the main damaging agents among other Ca2+-independent mechanisms of cellular injury. Because mitochondria, besides the endoplasmic reticulum, play a key role in the maintainance of cellular Ca2+ homeostasis, alterations in the mitochondrial Ca2+ content ([Ca2+](m)) were monitored in addition to changes in cytosolic Ca2+ concentration ([Ca2+](i)) during metabolic inhibition (MI) in renal epithelial Madin-Darby canine kidney (MDCK) cells. [Ca2+](i) and [Ca2+](m) were monitored via, respectively, fura 2 and rhod 2 measurements. MI induced an increase in [Ca2+](i) reaching 631 +/- 78 nM in similar to20 min, followed by a decrease to 118 +/- 9 nM in the next similar to 25 min. A pronounced drop in cellular ATP levels and a rapid increase in intracellular Na+ concentrations in the first 20 min of MI excluded Ca2+ efflux in the second phase via plasma membrane ATPases or Na+/Ca2+ exchangers (NCE). Mitochondrial rhod 2 intensities increased to 434 +/- 46% of the control value during MI, indicating that mitochondria sequester Ca2+ during MI. The mitochondrial potential (DeltaPsi(m)) was lost in 20 min of MI, excluding mitochondrial Ca2+ uptake via the DeltaPsi(m)-dependent mitochondrial Ca2+ uniporter after 20 min of MI. Under Na+-free conditions, or when CGP-37157, a specific inhibitor of the mitochondrial NCE, was used, no drop in [Ca2+](i) was seen during MI, whereas the MI-induced increase in mitochondrial rhod 2 fluorescence was strongly reduced. To our knowledge, this study is the first to report that in metabolically inhibited renal epithelial cells mitochondria take up Ca2+ via the NCE acting in the reverse mode.
Notes: Transnatl Univ Limburg, Limburgs Univ Ctr, Dept Physiol, Biomed Onderzoeksinst, B-3590 Diepenbeek, Belgium.Smets, I, Transnatl Univ Limburg, Limburgs Univ Ctr, Dept Physiol, Biomed Onderzoeksinst, Univ Campus Gebouw D, B-3590 Diepenbeek, Belgium.ilse.smets@luc.ac.be
URI: http://hdl.handle.net/1942/2319
DOI: 10.1152/ajprenal.00284.2003
ISI #: 000220033100023
ISSN: 0363-6127
Category: A1
Type: Journal Contribution
Validation: ecoom, 2005
Appears in Collections: Research publications

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