Near infrared spectroscopy: Blood and tissue oxygenation in renal ischemia-reperfusion injury in rats

Abstract

Near infrared spectroscopy was used to monitor blood (HbO₂, Hb, and Hb_tot) and tissue oxygenation (oxidized cyt aa₃) of both left and right kidneys of rats in vivo simultaneously, during either 45 or 80 minutes of left renal ischemia followed by 4.5 hours of reperfusion. Ischemia significantly reduced HbO₂ (p< 0.0001) and increased Hb (p<0.05) concentration change in the left kidney compared with the right kidney (control). Reperfusion with oxygenated blood reached control levels after 1 hour. The rate of change in HbO₂ (p<0.05) and Hb_tot (p<0.05) concentration during reperfusion was dependent upon the duration of ischemia, being slower after the longer ischemic period of 80 minutes. The concentration change of oxidized cyt aa₃ of the 80-minute ischemic group slowly increased compared with the stable redox state of the 45-minute ischemic group, during the latter stages of reperfusion (p<0.05). Near infrared spectroscopy is a promising new development that will enable the effects of interventional treatment upon ischemia and reperfusion injury to be studied.