Volume 2 Supplement 1

ESICM LIVES 2014

Open Access

0036. Confocal imaging of impaired mitochondrial function in the cerebral cortex of rats during haemorrhagic shock in vivo

  • KK Ida1, 2,
  • LMS Malbouisson1,
  • DA Otsuki1,
  • KI Chisholm2,
  • A Dyson3,
  • M Singer3,
  • MR Duchen4 and
  • KJ Smith2
Intensive Care Medicine Experimental20142(Suppl 1):O9

DOI: 10.1186/2197-425X-2-S1-O9

Published: 26 September 2014

Introduction

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.

Objectives

To investigate the effects of HS on mitochondrial function in the cerebral cortex of rats in vivo.

Methods

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.

Results

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).
https://static-content.springer.com/image/art%3A10.1186%2F2197-425X-2-S1-O9/MediaObjects/40635_2014_Article_37_Fig1_HTML.jpg
Figure 1

(A) Images of the somatosensory cortex at baseline, haemorrhagic shock, and at 30 and 60 minutes after shock. Green mitochondrial FAD autofluorescence indicates an oxygenated environment, and in shick this is only maintained within ~30-40 μm of arteries. (B) Ratio of the FAD (I) and TMRM (II) fluorescence intensity of the halo extending 30-40 μm, from arterioles/arteries to venules/veins in rats undergoing haemorrhagic shock. *Within a time-point, the value is significantly different from sham (p <0.01).

Conclusions

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.

Declarations

Grant acknowledgment

Programa Ciência sem Fronteiras 10464-4-12, UK MS Society, MRC.

Authors’ Affiliations

(1)
University of São Paulo, Medical School
(2)
University College London, Department of Neuroinflammation, Institute of Neurology
(3)
University College London, Bloomsbury Institute of Intensive Care Medicine
(4)
University College London, Department of Cell and Developmental Biology

References

  1. 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.2009.01.013PubMedView ArticleGoogle Scholar

Copyright

© Ida et al; licensee Springer. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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