AJP - Endocrinology and Metabolism, Vol 259, Issue 5 E729-E735, Copyright © 1990 by American Physiological Society
Brain glucose utilization and transport and cortical function in chronic vs. acute hypoglycemia
D. A. Pelligrino, L. J. Segil and R. F. Albrecht
Department of Anesthesiology, Michael Reese Hospital and Medical Center, Chicago, Illinois 60616.
We compared regional brain capillary permeability-surface area products for
glucose transfer (PSin), cerebral glucose utilization (rCMRGlc) rates, and
brain tissue glucose levels (GlCbr) in N2O-sedated, paralyzed, and
artificially ventilated rats during normoglycemia (NG), insulin-induced
acute hypoglycemia (AH), or chronic hypoglycemia (CH) [hypoglycemic plasma
glucose (Glcp) = 2.2-2.3 mumol/ml]. In addition, a comparative assessment
of brain function in AH vs. CH was performed employing somatosensory-evoked
response (SSER) technology. A double-label (3H and 14C) 2-deoxy-D-glucose
method was used for the simultaneous assessment of PSin and rCMRGlc.
Compared with normoglycemic controls, AH resulted in significant 40-50%
reductions in rCMRGlc in 10 of 11 regions analyzed (cerebellum unchanged).
In CH vs. AH, significantly higher values for rCMRGlc, Glcbr/Glcp ratios,
and PSin were seen in 8, 8, and 5 regions, respectively. No differences in
rCMRGlc were observed when comparing CH vs. NG groups. Furthermore, CH rats
were able to sustain normal SSER at levels of hypoglycemia (1.5 mumol/ml)
that, when imposed acutely, resulted in attenuated SSER. Thus CH is
associated with an enhanced blood-brain glucose transport capacity in many
(but not all) brain regions. This in turn increases rCMRGlc and improves
the general cerebral function compared with that seen during AH.
