Single channel studies of the ATP-regulated potassium channel in brain mitochondria.
Mitochondrial potassium channels in the brain have been suggested to have an important role in neuroprotection. The single channel activity of mitochondrial potassium channels was measured after reconstitution of the purified inner membrane from rat brain mitochondria into a planar lipid bilayer. In addition to a large conductance potassium channel that was described previously, we identified a potassium channel that has a mean conductance of 219 +/- 15 pS. The activity of this channel was inhibited by ATP/Mg(2+) and activated by the potassium channel opener BMS191095. Channel activity was not influenced either by 5-hydroxydecanoic acid, an inhibitor of mitochondrial ATP-regulated potassium channels, or by the plasma membrane ATP-regulated potassium channel blocker HMR1098. Likewise, this mitochondrial potassium channel was unaffected by the large conductance potassium channel inhibitor iberiotoxin or by the voltage-dependent potassium channel inhibitor margatoxin. The amplitude of the conductance was lowered by magnesium ions, but the opening ability was unaffected. Immunological studies identified the Kir6.1 channel subunit in the inner membrane from rat brain mitochondria. Taken together, our results demonstrate for the first time the single channel activity and properties of an ATP-regulated potassium channel from rat brain mitochondria.
Choma
Katarzyna
K
Department of Biophysics, Warsaw University of Life Sciences SGGW, 159 Nowoursynowska St., 02-776, Warsaw, Poland.
Bednarczyk
Piotr
P
Koszela-Piotrowska
Izabela
I
Kulawiak
Bogusz
B
Kudin
Alexei
A
Kunz
Wolfram S
WS
Dołowy
Krzysztof
K
Szewczyk
Adam
A
D000255:Adenosine Triphosphate / Q000008:administration & dosage*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D054086:KATP Channels; D008051:Lipid Bilayers / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013806:Theophylline / Q000031:analogs & derivatives
D054086:KATP Channels; D008051:Lipid Bilayers; D024661:Potassium Channels, Inwardly Rectifying; C092520:uK-ATP-1 potassium channel; D000255:Adenosine Triphosphate; D013806:Theophylline; C006683:bamifylline