Background: Acute kidney injury and its central pathology, renal ischemia reperfusion injury (IRI), have been studied in many animal models. Although renal IRI has been induced in pig models in many ways, simultaneous bilateral ischemia or unilateral ischemia along with contralateral nephrectomy models only provide data on the renal response to a single ischemia time. Moreover, it has been reported that prolonged renal ischemia time in pigs for 120 min or more can cause irreversible renal damage and increase animal mortality. Methods: We developed a model that induces prolonged ischemia time and subsequent reperfusion injury without threatening the lives of pigs by subjecting the left and right kidneys to ischemia for 120 and 60 min, respectively. Using this novel model, we investigated whether hydrogen gas inhalation could alleviate renal IRI. Results: All animals (n=4) survived until the end of the observation period of 3 months in this model. Evaluation of the left and right kidneys immediately before and after IRI could be performed separately by blood sampling from each renal vein and renal biopsy during surgery, although the results of peripheral blood sampling during the follow-up were the mixed results of bilateral kidneys. The release of degraded DNA from the kidneys immediately after IRI and subsequent renal fibrosis at 3 months increased in response to ischemia time. Although the effect of hydrogen gas on pathological findings was not obvious, the release of degraded DNA from the kidney, an acute marker of IRI, appeared to be suppressed. Conclusions: We have developed a novel model in which IRI of different ischemia times is induced in the bilateral kidney that provides two-fold information and allows for safe long-term observation experiments in pigs. Using this model, hydrogen gas inhalation appeared to reduce acute renal IRI, although the effect was not statistically significant.
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