Lysophospholipids caused the release of 45Ca2+ from isolated rat liver mitochondria incubated at 37 degrees C in the presence of low concentrations of free Ca2+, ATP, Mg2+, and phosphate ions. The concentrations of lysophosphatidylethanolamine, lysophosphatidylcholine, lysophosphatidic acid and lysophosphatidylinositol which gave half-maximal effects were 5, 26, 40 and 56 microM, respectively. The effects of lysophosphatidylethanolamine were not associated with a significant impairment of the integrity of the mitochondria as monitored by measurement of membrane potential and the rate of respiration. Lysophosphatidylethanolamine did not induce the release of Ca2+ from a microsomal fraction, or enhance Ca2+ inflow across the plasma membrane of intact cells, but did release Ca2+ from an homogenate prepared from isolated hepatocytes and incubated under the same conditions as isolated mitochondria. The proportion of mitochondrial 45Ca2+ released by lysophosphatidylethanolamine was not markedly affected by altering the total amount of Ca2+ in the mitochondria, the concentration of extramitochondrial Mg2+, by the addition of Ruthenium Red, or when oleoyl lysophosphatidylethanolamine was employed instead of the palmitoyl derivative. The effects of 5 microM-lysophosphatidylethanolamine were reversed by washing the mitochondria. The possibility that lysophosphatidylethanolamine acts to release Ca2+ from mitochondria in intact hepatocytes following the binding of Ca2+-dependent hormones to the plasma membrane is briefly discussed.
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December 1984
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Research Article|
December 01 1984
Effects of lysophospholipids on Ca2+ transport in rat liver mitochondria incubated at physiological Ca2+ concentrations in the presence of Mg2+, phosphate and ATP at 37° C
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1984 London: The Biochemical Society
1984
Biochem J (1984) 224 (2): 423–430.
Citation
S Dalton, B P Hughes, G J Barritt; Effects of lysophospholipids on Ca2+ transport in rat liver mitochondria incubated at physiological Ca2+ concentrations in the presence of Mg2+, phosphate and ATP at 37° C. Biochem J 1 December 1984; 224 (2): 423–430. doi: https://doi.org/10.1042/bj2240423
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