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Title: Effect of calcium on the energy status of rat brain synaptosomes under acidosis. Author: Levko AV, Aksentsev SL, Fedorovich SV, Konev SV. Journal: Biochemistry (Mosc); 1998 Feb; 63(2):180-4. PubMed ID: 9526111. Abstract: Incubation of rat brain synaptosomes at pH 6.0 in Ca2+-containing medium is associated with a decrease in the ATP content and the rate of oxygen consumption. ATP/ADP ratio decreased from 6.6 +/- 0.24 at pH 7.4 to 3.2 +/- 0.17 at pH 6.0. The content of 86Rb+ and [3H]tetraphenylphosphonium measured at pH 7.4 did not change after preincubation at pH 6.0, indicating the absence of lesion of synaptosomal plasma membranes and intrasynaptosomal mitochondria. Incubation with 1 mM EGTA in Ca2+-free medium as well as addition of 1 mM ouabain or 10 microM ruthenium red prevents the effect of acidosis. Similar results were obtained when 5 mM pyruvate was used as a mitochondrial substrate instead of glucose. It is suggested that acidosis-induced decrease in the ATP level is associated with the increase in Ca2+ concentration in the cytoplasm and its transport into mitochondria. Ouabain reverses this process due to activation of Na+/Ca2+ exchange.[Abstract] [Full Text] [Related] [New Search]