Submitted on July 19, 2006
Accepted on August 10, 2006
Use of a hanging-weight system for isolated renal artery occlusion during ischemic preconditioning in mice
Almut Grenz1, Tobias Eckle2, Hua Zhang3, Dan Yang Huang4, Manfred Wehrmann5, Christoph Köhle4, Klaus E Unertl2, Hartmut Osswald4, and Holger K. Eltzschig6*
1 Tübingen University Hospital, Department of Pharmacology and Toxicology, Tübingen, Germany
2 Tübingen University Hospital, Department of Anesthesiology and Intensive Care Medicine, Tübingen, Germany
3 Tübingen, University Hospital, Department of Pharmacology and Toxicology, Tuebingen, Germany
4 Tübingen, University Hospital, Department of Pharmacology and Toxicology, Tuebingen, Germany; Tübingen, Germany
5 Tübingen University Hospital, Department of Pathology, Tübingen, Germany
6 Tübingen, Germany; Tübingen University Hospital, Department of Anesthesiology and Intensive Care Medicine, Tübingen, Germany
* To whom correspondence should be addressed. E-mail: heltzschig{at}partners.org.
Renal failure from ischemia contributes to morbidity and mortality. Ischemic preconditioning (IP) represents a powerful strategy for kidney protection and recent advances in transgenic mice may help elucidating its molecular mechanisms. However, murine IP is technically challenging and experimental details significantly influence results. Thus, we developed a novel model for renal IP using a hanging-weight system for isolated renal artery occlusion. In contrast to previous models, this technique eliminates the need for clamping the vascular pedicle (artery/vein). In fact, assessment of renal injury after different time-periods of ischemia (10-60 min) revealed highly-reproducible increases in plasma-creatinine and -potassium levels, while creatinine-clearance, urinary-flow and potassium/sodium-excretion were significantly attenuated. Using different numbers of IP-cycles, we found maximal protection with 4 cycles of 4 min of ischemia/reperfusion. In contrast, no significant renal protection was observed with IP of the vascular pedicle. To assess transcriptional responses in this model, we isolated RNA from preconditioned kidneys and found time-dependent induction of erythropoietin-mRNA and plasma-levels with IP. Taken together, this model provides highly-reproducible renal injury and protection by IP, thus minimizing variability associated with previous techniques based on clamping of the renal pedicle. Further studies on renal ischemia/IP in mice may consider this technique.
