title: Real-time analysis of renal interstitial metabolites during induced renal ischemia*.
abstract: OBJECTIVE
  Microdialysis is an innovative technique used to monitor the chemistry of the interstitial fluid in living tissue. We documented changes in concentration of interstitial fluid metabolites before, during, and after induced renal ischemia.
  
  
  METHODS
  Under general anesthesia, a microdialysis probe was laparoscopically positioned into the renal cortex of six pigs. Isotonic sterile perfusion fluid was pumped through the probe at 2 microL/min. After collecting a baseline sample, the renal artery was occluded with a Satinsky clamp for 90 (n = 3) or 120 (n = 3) minutes. A dialysate sample was collected every 30 minutes during the ischemic and 3-hour postischemic period. The samples were analyzed for glucose, lactate, pyruvate, glutamate, urea, and glycerol concentrations with the CMA/600 Microdialysis Analyzer. Serum metabolic panels from peripheral venous samples drawn before ischemia, after ischemia, and 3 hours after ischemia were analyzed.
  
  
  RESULTS
  Glucose and pyruvate concentrations significantly declined (P = 0.01, P = 0.05, respectively) while lactate and glycerol concentrations significantly increased during ischemia (P = <0.01, P < 0.01, respectively). Glutamate increased to 2.5 times the baseline concentration (P < 0.01) at 1 hour of ischemia and subsequently declined during ischemia. The lactate/pyruvate ratio increased sharply during ischemia and returned to baseline within 1 hour postischemia. There were no changes noted in serum creatinine levels before and after ischemia.
  
  
  CONCLUSIONS
  Microdialysis can accurately measure minute real-time changes in the renal interstitial environment caused by ischemia not detected with serum studies. These local changes may be correlated with ischemic times to predict tissue preservation in future studies.
authors.affiliation: Department of Urology, Wilford Hall Medical Center, Lackland Air Force Base, TX 78236, USA. kyleweld@yahoo.com
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Weld
authors.forename: Claudio
authors.initials: C
authors.lastname: Montiglio
authors.forename: Anneke C
authors.initials: AC
authors.lastname: Bush
authors.forename: Hugh H
authors.initials: HH
authors.lastname: Harroff
authors.forename: R Duane
authors.initials: RD
authors.lastname: Cespedes
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D007511:Ischemia / Q000378:metabolism*; D007668:Kidney / Q000098:blood supply* / Q000378:metabolism; D010535:Laparoscopy; D017551:Microdialysis; D013552:Swine; D013997:Time Factors
chemical_list: D015415:Biomarkers