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A-78
2002
The Protective Effect of Isoflurane Against Renal Ischemia/Reperfusion Injury in Rats
Hiroshi Miyoshi, M.D.; Hiroaki Morooka, M.D.; Toshiya Tsujita, M.D.; Hideo Hashiguchi, M.D.; Koji Sumikawa, M.D.
Anesthesiology, Nagasaki University School of Medicine, Nagasaki, Japan
Background: Ischemia/reperfusion injury of brain, heart, liver or kidney is associated with high morbidity and mortality. Improving the ability of these organs to tolerate ischemia/reperfusion injury would have important implications. It was reported that volatile anesthetics had a preconditioning effect in brain, heart and liver. But there was no study to evaluate the effect of isoflurane for renal ischemia/reperfusion injury. This study was designed to evaluate the effect of isoflurane on renal function against renal ischemia/reperfusion injury in rats.

Methods: After the approval of Animal Care Committee, thirty-seven male wistar rats (220-300g) were anesthetized with pentobarbital sodium (55mg/kg intraperitoneally). Rats were intubated and mechanically ventilated with air. Animals were divided into three groups. Kidneys were exposed through flank incisions. Rats in group A (n=13) underwent sham surgery. Group B (n=13) and C (n=11) were subjected to bilateral renal ischemia by clamping both renal pedicles with nontraumatic microaneurysm clamps. After 40 minutes, clamps were removed. Group C received 1.5 % isoflurane from 20 minutes before ischemia to 20 minutes after reperfusion. Blood was drawn, and serum creatinine and blood urea nitrogen were determined 24 hours after surgery. The data were expressed as mean±SD. Differences among groups were analyzed by analysis of variance and Kruskal-Wallis's test. Unpaired Student's t-test analysis was used for statistical analysis of the each data. A p value less than 0.05 was considered statistically significant.

Results: The values of serum creatinine were 0.43±0.05 mg/dl, 3.65±0.97 mg/dl and 1.00±0.79 mg/dl in groups A, B and C, respectively. Serum creatinine showed a significant increase in group B compared to groups A and C (p<0.01). 05mg/dl The values of blood urea nitrogen were 17.6±3.3 mg/dl, 119.5±16.5 mg/dl and 47.8±20.1 mg/dl in groups A, B and C, respectively. Blood urea nitrogen showed a significant increase in group B compared to groups A and C (p<0.01).

Discussions: The results show that serum creatinine and blood urea nitrogen increase significantly by 40-minutes renal ischemia, while the continuous administration of isoflurane prevents this phenomenon. Although the mechanism of this renal protective effect is unknown, following explanations might be advanced. First, isoflurane might have a preconditioning effect against renal ischemia/reperfusion injury. Second, the vasodilator action of isoflurane on renal perfusion might extra protective effect against renal ischemia/reperfusion injury.

Conclusions: Isoflurane showed a renal protective effect against renal ischemia-reperfusion injury when it was administered from 20 minutes before ischemia to 20 minutes after reperfusion.

References: Am J. Physiol. Renal Physiol. 278: F380-F387, 2000. J. Biol. Chem. 276: 11870-11876, 2001.

Anesthesiology 2002; 96: A78