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.
Skalska
Jolanta
J
Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Piwońska
Marta
M
Wyroba
Elzbieta
E
Surmacz
Liliana
L
Wieczorek
Rafal
R
Koszela-Piotrowska
Izabela
I
Zielińska
Joanna
J
Bednarczyk
Piotr
P
Dołowy
Krzysztof
K
Wilczynski
Grzegorz M
GM
Szewczyk
Adam
A
Kunz
Wolfram S
WS
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