title: Detecting low-abundance vasoactive peptides in plasma: progress toward absolute quantitation using nano liquid chromatography-mass spectrometry.
abstract: Profiling changes in the concentration of functionally related peptide hormones is critical to understanding the etiology of many diseases and therapies. We present novel data using nano liquid chromatography-mass spectrometry (LC-MS) to simultaneously measure a select group of vasoactive peptides (angiotensin, bradykinin, and related hormones) in 50-microl plasma samples, enabling repeated sampling in rodent models. By chromatographically resolving target peptides and using multiple reaction monitoring to enhance MS sensitivity, linear responses down to 10(-17) mol were achieved. Purification of plasma peptides by either methanol precipitation or off-line high-performance liquid chromatography (HPLC) fractionation enabled the detection of endogenous peptides and revealed approaches for enhancing recovery. As proof of principle, seven vasoactive peptides were profiled before, during, and after acute angiotensin-converting enzyme (ACE) inhibition in an anesthetized rat. Of note was an apparent 10-fold increase in vasodilatory bradykinin that reversed after drug infusion but relatively minor changes in angiotensin II levels. Targeted MS analysis used to profile functionally related peptides or other analytes will greatly enhance our ability to define the sequence of events regulating complex and dynamic physiological processes.
authors.affiliation: Division of Nephrology and Hypertension, VA San Diego Healthcare System, Biomarker and Diagnotics Discovery Center, Department of Pathology, UCSD School of Medicine, San Diego, CA 92093-0612, USA. mlortie@ucsd.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Lortie
authors.forename: Steven
authors.initials: S
authors.lastname: Bark
authors.forename: Roland
authors.initials: R
authors.lastname: Blantz
authors.forename: Vivian
authors.initials: V
authors.lastname: Hook
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D036103:Nanotechnology; D010455:Peptides / Q000097:blood* / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D012015:Reference Standards; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D010455:Peptides