title: Measurement of plasma renin concentration in cats by use of a fluorescence resonance energy transfer peptide substrate of renin.
abstract: OBJECTIVE
  To evaluate the use of a commercially available 5-carboxyfluorescein-based, intramolecularly quenched, fluorescence resonance energy transfer (FRET) peptide substrate of renin for measurement of plasma renin concentration in cats.
  
  
  METHODS
  Plasma samples obtained during a previous study of renal autograft ischemia-reperfusion injury in 10 cats and samples of fetal bovine serum containing recombinant human renin (rh-renin).
  
  
  METHODS
  Experiments involving samples of fetal bovine serum containing rh-renin were conducted to identify a suitable control vehicle, optimal substrate concentration, and appropriate duration of incubation. With the use of the identified assay conditions, a standard curve was constructed to allow conversion of relative fluorescent units into values of renin concentration (ng/mL). Subsequently, plasma samples obtained from cats before and after renal autograft ischemia-reperfusion injury were assayed to determine endogenous renin concentration.
  
  
  RESULTS
  Under conditions of a 1:50 substrate dilution and 4-hour incubation period, the assay detected small amounts of rh-renin in fetal bovine serum. A linear relationship (R(2) = 0.996) between the relative fluorescent units generated and exogenous rh-renin concentration was evident. The assay detected renin in plasma samples obtained from cats after renal autograft ischemia-reperfusion, and renin concentrations on days 1 and 2 after transplant differed significantly.
  
  
  CONCLUSIONS
  The study data indicated that the assay involving the FRET peptide substrate of renin is potentially a rapid and specific method for measurement of plasma renin concentration in cats.
authors.affiliation: Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA. cws@uga.edu
authors.forename: Chad W
authors.initials: CW
authors.lastname: Schmiedt
authors.forename: Katherine A E
authors.initials: KA
authors.lastname: Hurley
authors.forename: Xiaohe
authors.initials: X
authors.lastname: Tong
authors.forename: Vera A
authors.initials: VA
authors.lastname: Rakhmanova
authors.forename: Cecilia L
authors.initials: CL
authors.lastname: Po
authors.forename: David J
authors.initials: DJ
authors.lastname: Hurley
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000097:blood*; D002415:Cats; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods / Q000662:veterinary*; D016030:Kidney Transplantation; D015427:Reperfusion Injury / Q000378:metabolism