Large-conductance Ca2+-activated potassium channel in mitochondria of endothelial EA.hy926 cells
PBN-AR
Instytucja
Wydział Biologii (Uniwersytet im. Adama Mickiewicza w Poznaniu)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
ISSN
0363-6135
EISSN
1522-1539
Wydawca
AMER PHYSIOLOGICAL SOC
DOI
URL
Rok publikacji
2013
Numer zeszytu
11
Strony od-do
1415-H1427
Numer tomu
304
Identyfikator DOI
Liczba arkuszy
Słowa kluczowe
en
Bioenergetics; Electrophysiology; Endothelium; Mitochondria; Potassium channel
Streszczenia
Język
en
Treść
In the present study, we describe the existence of a large-conductance Ca2+-activated potassium (BKCa) channel in the mitochondria of the human endothelial cell line EA.hy926. A single-channel current was recorded from endothelial mitoplasts (i.e., inner mitochondrial membrane) using the patch-clamp technique in the mitoplast-attached mode. A potassiumselective current was recorded with a mean conductance equal to 270 ± 10 pS in a symmetrical 150/150 mM KCl isotonic solution. The channel activity, which was determined as the open probability, increased with the addition of calcium ions and the potassium channel opener NS1619. Conversely, the activity of the channel was irreversibly blocked by paxilline and iberiotoxin, BKCa channel inhibitors. The open-state probability was found to be voltage dependent. The substances known to modulate BKCa channel activity influenced the bioenergetics of mitochondria isolated from human endothelial EA.hy926 cells. In isolated mitochondria, 100 μM Ca2+, 10 μM NS1619, and 0.5 μM NS11021 depolarized the mitochondrial membrane potential and stimulated nonphosphorylating respiration. These effects were blocked by iberiotoxin and paxilline in a potassiumdependent manner. Under phosphorylating conditions, NS1619-induced, iberiotoxin-sensitive uncoupling diverted energy from ATP synthesis during the phosphorylating respiration of the endothelial mitochondria. Immunological analysis with antibodies raised against proteins of the plasma membrane BKCa channel identified a poreforming α-subunit and an auxiliary β2-subunit of the channel in the endothelial mitochondrial inner membrane. In conclusion, we show for the first time that the inner mitochondrial membrane in human endothelial EA.hy926 cells contains a large-conductance calciumdependent potassium channel with properties similar to those of the surface membrane BKCa channel. © 2013 the American Physiological Society.
Cechy publikacji
ORIGINAL_ARTICLE
Inne
System-identifier
603113
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