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THE EFFECT OF LIMB ISCHAEMIA ON THE TURNOVER OF NORADRENALINE IN THE HYPOTHALAMUS AND BRAIN STEM OF THE RAT
Author(s) -
Stoner H. B.,
Elson Patricia M.,
Koltay Edit
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.tb04241.x
Subject(s) - hypothalamus , endocrinology , medicine , tyrosine , hindlimb , endogeny , ischemia , central nervous system , brain tissue , norepinephrine , chemistry , dopamine , biochemistry
The effect of ischaemic limb injury on the turnover of noradrenaline in the hypothalamus and brain stem has been studied in rats. There are theoretical reasons for thinking that these regions are activated in trauma and previous work showed that during limb‐ischaemia the concentration of noradrenaline in the hypothalamus decreased by 27 per cent. The tourniquets were applied to both hind‐limbs 1 h after the injection of [ 14 C]‐tyrosine when the labelling of the noradrenaline was maximal. During 4 h limb ischaemia the endogenous tyrosine concentration in the plasma decreased while that in the hypothalamus first rose and then fell. Changes in a similar direction in the brain stem were not statistically significant. Limb ischaemia did not affect the decline in the specific activity of the plasma or tissue tyrosine. It was concluded that the injury increased the utilization of tyrosine by the body. During the 4 h bilateral hind‐limb ischaemia the rate of decline of [ 14 C]noradrenaline was significantly increased in the brain stem but not in the hypothalamus. Conditions in the brain stem were sufficiently close to ‘steady‐state’ to be able to conclude that the injury increased the metabolism of noradrenaline in the brain stem. Conditions in the hypothalamus were too complicated for definite conclusions to be drawn. The possible reasons for this and the limitations of this method for studying noradrenaline turnover are discussed.