Increase of intracellular Ca²+ concentration induced by lysophosphatidylcholine in murine aortic endothelial cells

Effects of oxidized low-density lipoprotein (ox-LDL), l-α-stearoyl-lysophosphatidylcholine (LPC), on intracellular Ca²⁺ concentration were examined in mouse endothelial cells by measuring intracellular Ca²⁺ concentration ([Ca²⁺]_i) with fura 2-AM and reverse transcription-polymerase chain reaction (RT-PCR). LPC increased [Ca²⁺]_i under the condition of 1.5 mM [Ca²⁺]_o but did not show any effect under the nominally Ca²⁺-free condition. Even after the store depletion with 30 μM 2,5-di-tert-butylhydroquinone (BHQ) or 30 μM ATP, LPC could still increase the [Ca²⁺]_i under the condition of 1.5 mM [Ca²⁺]_o. The time required to increase [Ca²⁺]_i (about 1 minute) was longer than that for ATP-induced [Ca²⁺]_i increase (10 ∼ 30 seconds). LPC-induced [Ca²⁺]_i increase was completely blocked by 1 μM La³⁺. Transient receptor potential channel(trpc) 4 mRNA was detected with RT-PCR. From these results, we suggest that LPC increased [Ca²⁺]_i via the increase of Ca²⁺ influx through the Ca²⁺ routes which exist in the plasma membrane.