Effects of oleic acid on ionic channels of plasma membranes of green alga Chara corallina

Extracellular application of 5–30 μM oleic acid (C 18:1:9cis ) produced a significant decrease in the amplitude of Ca 2+ currents and Ca 2+ -activated chloride currents in plasma membrane of green alga Chara corallina . Introduction of 10 μM oleic acid intracellularly suppressed the development of the Ca 2+ current. This inhibition of the Ca 2+ current was reversible, and the Ca 2+ conductivity of the cell membrane was restored after the removal of oleic acid. There were no changes in the non-specific leakage current, which indicates the intactness of the lipid component of the membrane. An increase of the oleic acid concentration up to 50–100 μM in the extracellular solution induced almost complete and irreversible suppression of inward currents and caused a substantial increase in the non-specific leakage current and conductivity of plasma membrane, suggesting its disruption. We suggest that the mechanism of cytotoxicity of oleic acid may be related to transport across plasma membrane of oleic acid and its complexes with α-lactalbumin (HAMLET and La-OA).