title: Effect of potential-dependent potassium uptake on calcium accumulation in rat brain mitochondria.
abstract: The effect of potential-dependent potassium uptake at 0-120 mM K+ on matrix Ca2+ accumulation in rat brain mitochondria was studied. An increase in oxygen consumption and proton extrusion rates as well as increase in matrix pH with increase in K+ content in the medium was observed due to K+ uptake into the mitochondria. The accumulation of Ca2+ was shown to depend on K+ concentration in the medium. At K+ concentration ≤30 mM, Ca2+ uptake is decreased due to K+-induced membrane depolarization, whereas at higher K+ concentrations, up to 120 mM K+, Ca2+ uptake is increased in spite of membrane depolarization caused by matrix alkalization due to K+ uptake. Mitochondrial K+(ATP)-channel blockers (glibenclamide and 5-hydroxydecanoic acid) diminish K+ uptake as well as K+-induced depolarization and matrix alkalization, which results in attenuation of the potassium-induced effects on matrix Ca2+ uptake, i.e. increase in Ca2+ uptake at low K+ content in the medium due to the smaller membrane depolarization and decrease in Ca2+ uptake at high potassium concentrations because of restricted rise in matrix pH. The results show the importance of potential-dependent potassium uptake, and especially the K+(ATP) channel, in the regulation of calcium accumulation in rat brain mitochondria.
authors: Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kiev-24, Ukraine. a-dubensky@mail.ru
authors: O V
authors: OV
authors: Akopova
authors: L I
authors: LI
authors: Kolchinskaya
authors: V I
authors: VI
authors: Nosar
authors: V A
authors: VA
authors: Bouryi
authors: I N
authors: IN
authors: Mankovskaya
authors: V F
authors: VF
authors: Sagach
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011188:Potassium; D002118:Calcium