ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract— Previously reported interspecies correlations of cerebral cortical oxygen consumption (as a function of average species body weight) and of cerebral cortical chloride content and acetylcholinesterase activity (as functions of average species brain weight) were confirmed by selected repetitions of the determinations and were further validated by inclusion of data from samples of cerebral cortex of the fin whale (Balaenoptera physalus) and the sperm whale (Physeter catodon). Despite the fact that the samples of whale brain were obtained at 15–22 h after death and were preserved only by simply freezing on dry ice, no evidence of significant postmortem autolysis was obtained by examination of gangliosides, myelin basic proteins, acidic and amide residues of total isolated proteins, and lipid composition of cerebral cortical samples. The chloride content of whale cerebral cortex was 65.1 (± 12) μequiv./g, and the activity of acetylcholinesterase was 0.78 (± 0.28) μmol of acetylthiocholine hydrolysed min-1 g-1, with no differences in these values between the two species. The two interspecies correlations yielded regression curves with calculated slopes for chloride of +9.07 (± 0.37) and for acetylcholinesterase of -0–204 (± 0.006), each correlating significantly as functions of species brain weight at P 〈 0.001. Under optimal conditions of slow freezing and thawing of cerebral cortical slices equilibrated with 15 % (v/v) glycerol, oxygen consumption by the slices was only 50 per cent of the rate exhibited by fresh (unfrozen) slices. Despite the suboptimal conditions of freezing and thawing of the large (〉 200 g) samples of whale (and beef) brain, subsequently prepared slices of whale cerebral cortex respired at a rate of 20.6 (± 1.8) μmol of O2 taken up h-1 g-1, also 50 per cent of the value of 40.7 predicted by extrapolation for fresh (unfrozen) slices. When plotted as a function of species body weight, the data for oxygen consumption by previously frozen cortical slices paralleled the regression curve for fresh slices previously characterized by the expression, R = 5.4 W-0.1. The data obtained for the two species of great whales (brain weights, 6800–7800 g; body weights, 3–53 ± 104 kg) served to ‘anchor’ with more certainty the upper limits of the three interspecies correlations re-examined here and thus provided a better basis for predicting by extrapolation normal values for human cerebral cortex.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1973.tb12125.x
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