The Journal of Neurophysiology Vol. 85 No. 1 January 2001, pp. 125-133
Copyright ©2001 by the American Physiological Society

Does Anoxia Induce Cell Swelling in Carp Brains? In Vivo MRI Measurements in Crucian Carp and Common Carp

 ¹Bio-Imaging Lab, University Center Antwerp, University of Antwerp, 2020 Antwerp, Belgium; and  ²Division of General Physiology, Department of Biology, University of Oslo, N-0316 Oslo, Norway

Linden, Annemie Van der, Marleen Verhoye, and Göran E. Nilsson. Does Anoxia Induce Cell Swelling in Carp Brains? In Vivo MRI Measurements in Crucian Carp and Common Carp. J. Neurophysiol. 85: 125-133, 2001. Although both common and crucian carp survived 2 h of anoxia at 18°C, the response of their brains to anoxia was quite different and indicative of the fact that the crucian carp is anoxia tolerant while the common carp is not. Using in vivo T₂ and diffusion-weighted magnetic resonance imaging (MRI), we studied anoxia induced changes in brain volume, free water content (T₂), and water homeostasis (water diffusion coefficient). The anoxic crucian carp showed no signs of brain swelling or changes in brain water homeostasis even after 24 h except for the optic lobes, where cellular edema was indicated. The entire common carp brain suffered from cellular edema, net water gain, and a volume increase (by 6.5%) that proceeded during 100 min normoxic recovery (by 10%). The common carp recovered from this insult, proving that the changes were reversible and suggesting that the oversized brain cavity allows brain swelling during energy deficiency without a resultant increase in intracranial pressure and global ischemia. It is tempting to suggest that this is a function of the large brain cavity seen in many ectothermic vertebrates.