Effect of stepped hypoglycemia on the regional cerebral blood flow
response to physiologic brain activation.
Powers, William J., Irl B. Hirsch, and Philip E. Cryer.
Departments of Neurology, Radiology (Division of Radiological
Sciences), Medicine (Division of Endocrinology, Diabetes and
Metabolism) of the Washington University School of Medicine, St.
Louis, MO and the Lillian Strauss Institute for Neuroscience of the
Jewish Hospital of St. Louis
APStracts 2:0361H, 1995.
The effect of vasoactive stimuli on cerebral blood flow (CBF) has been
variously reported as normal or impaired by hypoglycemia. We measured
regional CBF in contralateral somatosensory cortex at rest and during
vibrotactile stimulation of one hand in four normal awake human
volunteers during (A) fasting euglycemia (5.1 - 5.2 [mu]mol ml-1)
with 0.9% saline infusion, (B) euglycemia (5.0 - 5.2 [mu]mol ml-1)
with hyperinsulinemic clamp, _ mild hypoglycemia (3.2 - 3.6 [mu]mol
ml-1) with hyperinsulinemic clamp and (D) moderate hypoglycemia (2.3
- 3.2 [mu]mol ml-1) with hyperinsulinemic clamp. No changes in mean
arterial pressure, PaCO2 or arterial oxygen content occurred. There
was no change in the magnitude of the normalized rCBF response to
physiologic brain stimulation with progressive arterial hypoglycemia
( r=0.10, p=0.73). We interpret this to mean that there was a
progressive reduction in cerebral glucose delivery to the area of
physiological activation as arterial glucose concentrations fell.
Therefore, the increase in regional CBF during physiological brain
activation is not regulated by a mechanism which matches local
cerebral glucose supply to local cerebral glucose demand.
Received 8 May 1995; accepted in final form 8 August 1995.
APS Manuscript Number H440-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.