Mechanisms of lysophosphatidylcholine-induced increase in intracellular calcium in rat cardiomyocytes

Previous reports have demonstrated that lysophosphatidylcho-line (LPC) increases the intracellular concentration of calcium ([Ca11]i) in the heart; however, the mechanisms responsible for this increase are not clear. We examined the effect of exoge-nous LPC on [Ca11]i in freshly isolated cardiomyocytes from adult rats. Our results showed that LPC elevated the [Ca11]i in a dose-dependent (2.5–10 mM) manner. The LPC (10 mM)-induced increase in [Ca11]i was augmented upon increasing the concentration of extracellular Ca11 and was abolished by the removal of Ca11 from the medium. Preincubation of cardi-omyocytes with sarcolemmal L-type Ca11 channel blocker, verapamil, did not affect the LPC-evoked increase in [Ca11]i significantly. On the other hand, ouabain, a Na1-K1 ATPase inhibitor, and low concentrations of extracellular Na1 enhance