Glucose concentration gradient through the cerebral cortex in normoglycaemic anaesthetized rabbits.
In this pilot study, the relationships between glucose and lactate concentrations of plasma, cerebrospinal fluid (CSF), cerebral cortex and subjacent white matter were investigated in one hyperglycaemic and three normoglycaemic anaesthetized rabbits. After a 90 min stabilization period, CSF was sampled and the brain frozen in situ. Triplet samples (n = 3 X 21) were obtained from the outer and inner halves of cortex and from the white substance and analysed for their water content as well as for glucose and lactate by enzymatic fluorescence methods. Preservation of the ATP content was demonstrated in brain slices by a bioluminescence method. The glucose and lactate levels of CSF seemed to reflect those of the outer half of the cortex. In the normoglycaemic animals, the tissue glucose and tissue lactate levels correlated inversely (r = 0.477: p less than 0.01). While the glucose concentrations were nearly identical in the inner cortex and white substance, there was a concentration difference of 0.54 mmol/kg tissue water between the outer half of the cortex and the white matter (p much less than 0.02). This might correspond to a steep intra-cortical glucose gradient starting from the CSF-facing surface and approximating the general cerebral glucose level in a depth of about 4-500 microns. The possible significance of this gradient in regulating CSF glucose is discussed.
Vámosi
B
B
Department of Neurology and Psychiatry, University Medical School, Debrecen, Hungary.
Bereczki
D
D
Nagy
E
E
D000768:Anesthesia, General; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000134:cerebrospinal fluid / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D008297:Male; D011817:Rabbits
D001786:Blood Glucose; D007773:Lactates; D005947:Glucose