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Electrophysiological evidence for the presence of a new chloride channel in rat brain mitochondrial inner membrane
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Farzad Shayanfar   , Javad Fahanik-Babaei , Naser Khodaee Ataloo , Reza Saghiri , Afsaneh Eliassi * |
| 1. Department of Physiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran 5. Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran |
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Abstract: (12771 Views) |
Background and aim: Chloride channels are present in mitochondrial membranes where they regulate volume and acidity of cells and organelles, cell signaling, and protective mechanisms of the cells. We have previously reported the presence of a 301 pS chloride channel in mitochondrial inner membrane of the rat brain. In this work we characterized biophysical properties of a new chloride channel in the mitochondrial inner membrane of the rat brain.
Methods: The rat brain was harvested and homogenized in the MSE-nagarase lysis buffer. The homogenate was centrifuged in 3 steps in MSE-digitonin, H2O, Na2CO3, respectively. Vesicles of mitochondrial inner membrane were then extracted in MSE solution. The membrane lipid L-α-Phosphatidylcholine was extracted from fresh egg yolk. Bilayer lipid membrane was formed in a 200 μm diameter hole. All recorded data were filtered at 1 kHz and stored at a sampling rate of 10 kHz for offline analysis by PClamp10 software. Statistical analysis was performed by Markov's noise-free single channel analysis.
Results: Channel incorporation into planar lipid bilayer revealed a selective anion channel with a conductance of 158 pS in 200 mM KCl cis/50 mM KCl trans electrolyte. The channel open probability appeared to be voltage dependent as the channel was very active at the voltages between ± 20 mV. Adding the chloride channel inhibitor DIDS in the side corresponding to the cell internal medium (cis) caused a strong inhibition of the channel activity.
Conclusion: Our results indicate the presence of a chloride channel in the mitochondrial inner membrane of the rat brain. This channel might play a role in maintaining proper pH level, regulation of membrane potential, ATP synthesis, and cell protection.
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| Keywords: Bilayer lipid membrane, Chloride channel, Mitochondrial inner membrane |
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Full-Text [PDF 1371 kb]
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Type of Study: Original Research |
Subject:
Electrophysiology
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