Lysophosphatidylcholine (LPC) metabolism and cardiac arrhythmias

The effect of LPC in the production of cardiac arrhythmias in isolated mammalian hearts has been well-documented. Cardiac arrhythmias are initiated by the accumulation of the lysolipid in the cardiac membrane. When isolated rat hearts were perfused in 10 μM LPC for 10 min, severe arrhythmias were observed in all experiments. In isolated guinea pig hearts that were perfused under identical conditions, the development of severe arrhythmias was never observed, and mild arrhythmias were produced in less than 50% of the hearts used. When the hearts of both species were perfused with [14C-palmitate]-LPC, the labellings found in the microsomal fractions (expressed in mg protein) were similar. However, a higher amount of labelled LPC (2-fold) was found in rat heart microsomes, whereas a higher amount of labelled fatty acid was located in the guinea pig heart microsomes. Determination of lysophospholipase activities in these microsomal fractions revealed that the specific activity of the enzyme was much higher in the guinea pig heart than the rat heart. The authors conclude that the differential effect of LPC-induced arrhythmias between the rat and guinea pig heart may be a direct result of the lysophospholipase activities in these hearts. The ability to catabolize LPC more rapidly in the guinea pig heart may decrease the accumulation of LPC in the membrane, and hence, reduce the production of arrhythmias