Lack of evidence for a remote effect of renal ischemia/reperfusion acute kidney injury on outcome from temporary focal cerebral ischemia in the rat

Objective: 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. Design: 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. Setting: Laboratory. Participants: Male Wistar rats. Interventions: Combined or isolated BRAO and MCAO. Measurements and Main Results: 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). Conclusions: 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.