Increase of Intracellular Ca<SUP>2&#8290;</SUP> Concentration Induced by Lysophosphatidylcholine in Murine Aortic Endothelial Cells

Increase of Intracellular Ca<SUP>2&#8290;</SUP> Concentration Induced by Lysophosphatidylcholine in Murine Aortic Endothelial Cells

<P> Effects of oxidized low-density lipoprotein (ox-LDL), l-α-stearoyl-lysophosphatidylcholine (LPC), on intracellular Ca<SUP>2&#8290;</SUP> concentration were examined in mouse endothelial cells by measuring intracellular Ca<SUP>2&#8290;</SUP> concentration ([Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB>) with fura 2-AM and reverse transcription-polymerase chain reaction (RT-PCR). LPC increased [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> under the condition of 1.5 mM [Ca<SUP>2&#8290;</SUP>]<SUB>o</SUB> but did not show any effect under the nominally Ca<SUP>2&#8290;</SUP>-free condition. Even after the store depletion with 30μM 2,5-di-tert- butylhydroquinone (BHQ) or 30μM ATP, LPC could still increase the [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> under the condition of 1.5 mM [Ca<SUP>2&#8290;</SUP>]<SUB>o</SUB>. The time required to increase [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> (about 1 minute) was longer than that for ATP-induced [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> increase (10∼30 seconds). LPC-induced [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> increase was completely blocked by 1μM La<SUP>3&#8290;</SUP>. Transient receptor potential channel(trpc) 4 mRNA was detected with RT-PCR. From these results, we suggest that LPC increased [Ca<SUP>2&#8290;</SUP>]<SUB>i</SUB> via the increase of Ca<SUP>2&#8290;</SUP> influx through the Ca<SUP>2&#8290;</SUP> routes which exist in the plasma membrane.