Electrophysiological Studies of Mitochondrial Channels

Campo, María Luisa; Muro, Concepción; Tedeschi, Henry; Kinnally, Kathleen W.

doi:10.1007/978-1-4615-5899-6_2

Cited by 3 publications

(3 citation statements)

References 46 publications

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“…A biphasic dose response was observed with the 1.3-nanosiemens megachannel (counterpart of PTP in electrophysiological studies) and the hydrophobic compounds antimycin A and protoporphyrin IX in studies of the inner mitochondrial membrane of mitoplasts using patch clamp techniques (97,98). Low concentrations of these compounds decrease the open probability of the 1.3-nanosiemens megachannel, whereas higher concentrations facilitate channel opening.…”

Section: Discussionmentioning

confidence: 99%

Long-chain Ceramide Is a Potent Inhibitor of the Mitochondrial Permeability Transition Pore

Novgorodov

Gudz

Obeid

2008

Journal of Biological Chemistry

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The sphingolipid ceramide has been implicated in mediating cell death that is accompanied by mitochondrial functional alterations. Moreover, ceramide has been shown to accumulate in mitochondria upon induction of apoptotic processes. In this study, we sought to evaluate the effects of natural, highly hydrophobic long-chain ceramides on mitochondrial function in vitro. Ceramide in a dodecane/ethanol delivery system inhibited the opening of the mitochondrial permeability transition pore (PTP) induced by either oxidative stress, SH group cross-linking, or high Ca 2؉ load, suggesting that the inhibitory point is at a level at which major PTP regulatory pathways converge. Moreover, ceramide had no effect on well known mitochondrial components that modulate PTP activity, such as cyclophilin D, voltage-dependent anion channel, adenine nucleotide transporter, and ATP synthase. The inhibitory effect of ceramide on PTP was not stereospecific, nor was there a preference for ceramide over dihydroceramide. However, the effect of ceramide on PTP was significantly influenced by the fatty acid moiety chain length. These studies are the first to show that long-chain ceramide can influence PTP at physiologically relevant concentrations, suggesting that it is the only known potent natural inhibitor of PTP. These results suggest a novel mechanism of ceramide regulation of mitochondrial function.

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Section: Discussionmentioning

confidence: 99%

Long-chain Ceramide Is a Potent Inhibitor of the Mitochondrial Permeability Transition Pore

Novgorodov

Gudz

Obeid

2008

Journal of Biological Chemistry

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“…Cells (pellet volume between ∼0.3 and 1.2 ml) were re‐suspended in 10 ml 1× isolation medium (230 mM mannitol, 70 mM sucrose, 5 mM HEPES pH 7.4) and homogenized by hand for three strokes. The remainder of the mitochondrial isolation was a modification of the method of Campo et al [21]. Mitoplasts were prepared from mitochondria by passage through a French press at 2000 psi according to the method of Decker and Greenawalt [22] as previously described [23].…”

Section: Methodsmentioning

confidence: 99%

Overexpression of Bcl‐2 suppresses the calcium activation of a mitochondrial megachannel

2001

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The molecular mechanism(s) by which Bcl-2 regulates apoptosis is poorly understood. Bcl-2 suppresses apoptosis by inhibiting calcium activation of the permeability transition of mitochondria. In this patch-clamp study, overexpression of Bcl-2 in mitochondria of cultured cells suppressed calcium activation of a high conductance channel that may underlie the permeability transition. All other single channel parameters were identical when multiple conductance channel activities of mitochondria from control and Bcl-2 overexpressing cells were compared. Bcl-2 forms channels in artificial membranes; however, no novel channel activities could be linked to Bcl-2 overexpression, suggesting Bcl-2 does not form channels in native inner membranes of mitochondria. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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“…Mitoplasts were pelleted by centrifugation for 10 min at 4810× g (5500 rpm) and suspended in ∼300 μl of 1×isolation medium. Mitoplasts from mouse kidney were prepared according to the method of Campo et al [13].…”

Section: Methodsmentioning

confidence: 99%

Two high conductance channels of the mitochondrial inner membrane are independent of the human mitochondrial genome

et al. 1998

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Patch-clamp techniques were used to characterize the channel activity of mitochondrial inner membranes of two human osteosarcoma cell lines: a mitochondrial genome-deficient (b b H ) line and its corresponding parental (b b + ) line. Previously, two high conductance channels, mitochondrial Centum picoSiemen (mCS) and multiple conductance channels (MCC), were detected in murine mitochondria. While MCC was assigned to the protein import in yeast mitochondria, the role of mCS is unknown. This study demonstrates that mCs and MCC activities from mouse mitochondria are indistinguishable from those of human mitochondria. The channel activities and their functional expression levels are not altered in cells lacking mtDNA. Hence, b b H cells may provide a model system for elucidating the role of mitochondrial channels in disease processes and apoptosis.z 1998 Federation of European Biochemical Societies.

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Electrophysiological Studies of Mitochondrial Channels

Cited by 3 publications

References 46 publications

Long-chain Ceramide Is a Potent Inhibitor of the Mitochondrial Permeability Transition Pore

Long-chain Ceramide Is a Potent Inhibitor of the Mitochondrial Permeability Transition Pore

Overexpression of Bcl‐2 suppresses the calcium activation of a mitochondrial megachannel

Two high conductance channels of the mitochondrial inner membrane are independent of the human mitochondrial genome

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