A novel potassium channel in skeletal muscle mitochondria.
In this work we provide evidence for the potential presence of a potassium channel in skeletal muscle mitochondria. In isolated rat skeletal muscle mitochondria, Ca(2+) was able to depolarize the mitochondrial inner membrane and stimulate respiration in a strictly potassium-dependent manner. These potassium-specific effects of Ca(2+) were completely abolished by 200 nM charybdotoxin or 50 nM iberiotoxin, which are well-known inhibitors of large conductance, calcium-activated potassium channels (BK(Ca) channel). Furthermore, NS1619, a BK(Ca)-channel opener, mimicked the potassium-specific effects of calcium on respiration and mitochondrial membrane potential. In agreement with these functional data, light and electron microscopy, planar lipid bilayer reconstruction and immunological studies identified the BK(Ca) channel to be preferentially located in the inner mitochondrial membrane of rat skeletal muscle fibers. We propose that activation of mitochondrial K(+) transport by opening of the BK(Ca) channel may be important for myoprotection since the channel opener NS1619 protected the myoblast cell line C2C12 against oxidative injury.
Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Jolanta
J
Skalska
Marta
M
Piwońska
Elzbieta
E
Wyroba
Liliana
L
Surmacz
Rafal
R
Wieczorek
Izabela
I
Koszela-Piotrowska
Joanna
J
Zielińska
Piotr
P
Bednarczyk
Krzysztof
K
Dołowy
Grzegorz M
GM
Wilczynski
Adam
A
Szewczyk
Wolfram S
WS
Kunz
D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D018999:Charybdotoxin / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013367:Submitochondrial Particles / Q000187:drug effects / Q000502:physiology*
D001562:Benzimidazoles; D015221:Potassium Channels; D018999:Charybdotoxin; C086491:NS 1619; D002118:Calcium