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METABOLIC CHANGES IN THE BRAINS OF MICE FROZEN IN LIQUID NITROGEN
Author(s) -
Pontén U.,
Ratcheson R. A.,
Siesjö B. K.
Publication year - 1973
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1973.tb07566.x
Subject(s) - phosphocreatine , creatine , hypoxia (environmental) , chemistry , liquid nitrogen , cerebral cortex , endocrinology , metabolite , hypoxic hypoxia , medicine , biochemistry , oxygen , biology , blood pressure , energy metabolism , organic chemistry
— Autolytic changes in the mouse brain, occurring during immersion of the animal in liquid nitrogen, were evaluated by measuring the tissue concentrations of glucose, lactate, pyruvate, α‐oxoglutarate, phosphocreatine, creatine, ATP, ADP and AMP. The values thus obtained were compared with those obtained in paralysed mice under nitrous oxide anaesthesia, the brains of which were frozen in such a way that arterial blood pressure and oxygénation were upheld during the freezing. Immersion of unanaesthetized mice in liquid nitrogen gave rise to significant alterations in phosphocreatine, creatine, lactate, lactate/pyruvate ratio, ADP and AMP. A comparison with values obtained in paralysed and anaesthetized mice that were frozen by immersion in liquid nitrogen showed that the metabolic changes observed in the unanaesthetized animals could not be caused by an anaesthetic effect on the metabolic pattern. It is concluded that autolysis in the mouse brain occurs during immersion of the animal in a coolant, mainly because arterial hypoxia develops before the tissue is frozen. A comparison with previous results on rat cerebral cortex indicates that mice offer no advantage for studies of cerebral metabolites in unanaesthetized animals. In both species, accurate analyses of labile cerebral metabolites require that the brain is frozen in a way that prevents arterial hypoxia during the fixation of the tissue.