Abstract 291: RAS Fingerprinting: Patient-Specific Evaluation of the Renin-Angiotensin-System in Plasma by LC-MS/MS-Based Multiplex Quantification of Angiotensin Peptides

Abstract

The Renin-Angiotensin-System (RAS) is critically involved in the regulation of important physiological functions including blood pressure and fluid balance. It is constituted by multiple enzymes giving rise to a meshwork of effector peptides, which mediate their functions through binding to specific receptor molecules. Therefore, the modification of angiotensin peptide levels represents a common strategy for the treatment of RAS-associated diseases and is frequently achieved by the pharmacologic regulation of enzymes taking part in angiotensin metabolism. We developed a highly sensitive method, which allows the simultaneous absolute quantification of up to 10 different angiotensin peptides in human plasma and whole blood (RAS-Fingerprinting). Either the measurement of in vivo RAS-Fingerprints (immediate sample stabilization) or heparin derived ex vivo RAS-Fingerprints in plasma or whole blood, provide unique insights into the biochemical constitution of the human RAS and therefore represent powerful tools for the patient specific evaluation of this physiologically important peptide hormone system. During the development and validation of a new LC-MS/MS based method for angiotensin quantification, comprehensive datasets for various applications of RAS-Fingerprinting have been generated. RAS-Fingerprints were measured in blood of healthy volunteers during the treatment with different RAS-blockers, which provided deep insights in the physiology and regulation of the human RAS and revealed surprising differences between individual patients. With the help of RAS-Fingerprinting, we were able to re-draw the picture of the human RAS at a previously unachieved level of detail and accuracy. Due to the availability of new selection criteria for pharmacologic screens, RAS-Fingerprinting could contribute to the development of innovative therapeutic approaches affecting the RAS. The extensive utilization of RAS-Fingerprinting in clinical studies will substantially enhance our understanding of the human RAS and could lead to the development of personalized treatment schemes in the management of RAS-associated diseases in the near future.