Unique molecular signatures of glycerophospholipid species in different rat tissues analyzed by tandem mass spectrometry.

Glycerophospholipids (GPL) in animal tissues are composed of a large array of molecular species that mainly differ in the fatty acyl composition. In order to further understand the roles of GPL at the molecular level, it is necessary to have comprehensive, accurate accounts of the molecular makeup for these molecules in animal tissues. However, this task was difficult simply because the conventional technologies of profiling GPL species depended heavily on technical skill for accuracy and reliability and were extremely labor-intensive. In recent years, tandem mass spectrometry (MS/MS) proved to be a highly reliable and sensitive technology for profiling small molecules, including GPL, in biological samples. In this study, we used this technology to perform simultaneous comparative analyses for phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI) in the same lipid preparations of liver, lung, kidney, heart, pancreas, stomach, small intestine, spleen, skeleton muscle and brain of an adult rat. We produced molecular profiles of these 4 GPL classes in these 10 different tissues that are highly reproducible between different scans of the same sample and between samples from different animals. It is intriguing that each tissue was found to possess a unique signature of GPL profile that may be used to identify unknown tissues. More importantly, these profiles may also set reference points for studying changes of GPL metabolism in different physiological and pathological conditions.