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 30μM 2,5-di-tert- butylhydroquinone (BHQ) or 30μM 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 1μM 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.