Lack of Evidence for a Remote Effect of Renal Ischemia/Reperfusion Acute Kidney Injury on Outcome from Temporary Focal Cerebral Ischemia in the Rat

Abstract

Acute kidney injury (AKI) and ischemic stroke may occur in the same cardiac surgical patient. It is not known if an interaction exists between these organ injuries. Isolated renal ischemia/reperfusion is associated with dysfunction in remote, otherwise normal organs, including the brain. In a rat model of simultaneous bilateral renal artery occlusion (BRAO) and middle cerebral artery occlusion (MCAO), the authors tested the hypothesis that AKI would worsen experimental stroke outcome. Sixty thermoregulated anesthetized rats were randomized to (1) 40-minute BRAO, (2) 80-minute MCAO, or (3) simultaneous BRAO + MCAO. Serum creatinine was measured at baseline and 2 and 7 days after organ reperfusion. Neurologic function and brain and kidney histologies were measured on day 7. In a parallel study, serum cytokines were measured over 16 hours. Laboratory. Male Wistar rats. Combined or isolated BRAO and MCAO. AKI was similar between the BRAO and BRAO + MCAO groups, with greater 48-hour creatinine increases (p < 0.02) and renal histopathologic scores (p < 0.001) in these groups than with MCAO alone. Neurologic scores correlated with cerebral infarct size (p = 0.0001). There were no differences in neurologic score (p = 0.53) and cerebral infarct volume (p = 0.21) between the MCAO and BRAO + MCAO groups. There was no association between cerebral infarct size or neurologic score and 48-hour creatinine increase. Interleukin-6 was increased during reperfusion (p < 0.0001), but a difference among groups was absent (p = 0.41). In contrast to the effects reported for AKI on normal remote organs, AKI had no influence on infarct size or neurologic function after experimental ischemic cerebral stroke.