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Keywords:

  • Asymmetrical dimethylarginine;
  • cardiovascular physiology;
  • ischaemia–reperfusion;
  • lipocalin-2;
  • renal failure;
  • suprarenal aortic-clamping

Eur J Clin Invest 2011; 41 (6): 605–615

Abstract

Background  Renal failure is a frequent complication of juxtarenal abdominal aortic aneurysm (JAA)-repair. During this operation, suprarenal aortic-clamping is followed by infrarenal aortic-clamping (below renal arteries) to restore renal flow, while performing the distal anastomosis. We hypothesized that infrarenal aortic-clamping, despite restoring renal perfusion provokes additional renal damage.

Materials and methods  We studied three groups of rats. After 45 min of suprarenal aortic-clamping, group 1 had renal reperfusion for 90 min without aortic-clamps (n = 7). In group 2, 45 min of suprarenal aortic-clamping with a distal clamp on the aortic-bifurcation was followed by 20 min of infrarenal aortic-clamping. Renal reperfusion was continued for 70 min without aortic-clamps (i.e. 90 min of renal reperfusion; n = 8). The sham-group had no clamps (n = 7). We measured renal haemodynamics, functional parameters and tissue damage.

Results  On suprarenal aortic-clamp removal, renal artery flow, cortical flow and arterial pressures were higher in group 2 than in group 1. We detected increased tubular brush border damage, luminal lipocalin-2 and 30–60% higher renal protein nitrosylation in group 2 when compared to group 1 (P < 0·05). Group 2 showed more release of asymmetrical dimethylarginine (ADMA) from the kidneys in the renal vein, therefore indicating diminished clearing capacity (P < 0·001). Arginine/ADMA-ratio, which defines the bio-availability of nitric oxide, tended to be lower in group 2 and correlated with renal flow. Furthermore, there were no significant differences found in creatinine levels and renal leucocyte accumulation between group 1 and 2.

Conclusions  Additional infrarenal aortic-clamping leads to increased renal damage and oxidative stress, despite adequate perfusion of kidneys after suprarenal aortic-clamping. This study indicates that the clamping sequence used in JAA-repair causes more than simple renal I/R-injury.