Effects of elevated plasma epinephrine on glucose utilization and
blood flow in conscious rat brain.
Horinaka, Naoaki, Nicole Artz, Michelle Cook, Courtney Holmes.
David S. Goldstein, Charles Kennedy, and Louis Sokoloff
APStracts 3:0490H, 1996.
Acute glucoprivation increases cerebral blood flow (CBF) which is
often attributed to the associated rise in plasma epinephrine levels.
This study examined directly the effects of comparable increases in
plasma epinephrine levels achieved by continuous intravenous
infusions of epinephrine in normoglycemic, unanesthetized rats on
local and overall CBF and cerebral glucose utilization (lCMRglc). CBF
was determined by the autoradiographic [14C]iodoantipyrine method in
six unanesthetized rats in which epinephrine dissolved in 1% ascorbic
acid / 1 mM EDTA was infused at a rate of 1 [mu]g/min and in five
normal controls infused with the vehicle alone. lCMRglc was
determined by the autoradiographic [14C]deoxyglucose method in six
conscious rats infused similarly with the epinephrine solution and in
six normal controls treated with the vehicle alone. The epinephrine
infusions raised arterial plasma epinephrine levels 10-20 fold and
increased arterial blood pressure and plasma glucose levels. lCBF,
however, was significantly changed (p<0.05, Student t test) in
only two of 25 structures examined, and the changes were decreases,
not increases. lCMRglc was not changed significantly in any of 42
brain structures examined, and average blood flow and glucose
utilization in the brain as whole was unaffected. These results show
that high circulating levels of epinephrine similar to those
accompanying glucoprivation alter neither local nor overall cerebral
blood flow and glucose utilization and cannot explain the increases
in CBF associated with glucoprivation.
Received 24 April 1996; accepted in final form 6 November 1996.
APS Manuscript Number H362-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996