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0036. Confocal imaging of impaired mitochondrial function in the cerebral cortex of rats during haemorrhagic shock in vivo
Intensive Care Medicine Experimentalvolume 2, Article number: O9 (2014)
Haemorrhagic shock (HS)-induced hypotension impairs cerebral perfusion pressure and decreases oxygen supply to the brain (1), but the consequences for brain mitochondrial function are poorly understood.
To investigate the effects of HS on mitochondrial function in the cerebral cortex of rats in vivo.
A flap of skull was removed and cerebral cortex exposed in isoflurane-anaesthetised rats undergoing HS (target mean arterial pressure (MAP) of 40 mmHg for 30 minutes) (n=7) compared with sham (n=6) controls. Mitochondrial function was assessed by observing mitochondrial membrane potential (using tetramethyl rhodamine methyl ester (TMRM); ex: 543 nm; em: 585 nm), and endogenous flavin adenine dinucleotide (FAD) autofluorescence (ex: 488 nm; em: 505-570 nm) by confocal imaging. The TMRM and FAD signals were registered before induction of HS (baseline), at MAP of 40 mmHg (shock), and at 30 (T30) and 60 (T60) minutes after shock.
There was a loss of mitochondrial membrane potential (decreased TMRM signal; p < 0.001) and reduction of the FAD/FADH2 pair (seen as decreased FAD fluorescence; p < 0.01) at both T30 and T60 post-shock, except for a striking protection observed as a 'halo' extending ~30-40 mm from arterioles (Figure 1). No loss of mitochondrial function was observed in sham controls (MAP >90 mmHg in all animals at both T30 and T60).
HS-induced hypotension causes a marked loss of mitochondrial membrane potential and FAD fluorescence in cerebral cortex, except in regions in immediate proximity to arterioles. This study reveals a profound spatial vulnerability of cortical tissue to reduced blood flow.
Cavus E, Meybohm P, Doerges V, et al.: Cerebral effects of three resuscitation protocols in uncontrolled haemorrhagic shock: a randomised controlled experimental study. Resuscitation 2009, 80: 567–72. 10.1016/j.resuscitation.2009.01.013
Programa Ciência sem Fronteiras 10464-4-12, UK MS Society, MRC.