Stroke, Vol 20, 275-280, Copyright © 1989 by American Heart Association
Effect of nimodipine on cerebral blood flow and metabolism in rats during hyperventilation
WL Young and S Chien
Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, New York.
Nimodipine shws promise in the prevention and treatment of brain ischemia.
We examined the interaction of nimodipine pretreatment in a dose sufficient
to prevent postischemic hypoperfusion and hyperventilation. We studied four
groups of rats: normocarbia plus vehicle (Group 1, n = 5), hypocarbia plus
vehicle (Group 2, n = 4), normocarbia plus nimodipine (Group 3, n = 7), and
hypocarbia plus nimodipine (Group 4, n = 6). Groups 3 and 4 received 1
mg/kg i.p. nimodipine, and Groups 1 and 2 received an equivalent amount of
vehicle. Ventilation was left unaltered in Groups 1 and 3 or increased to
lower PaCO2 to 21-24 mm Hg in Groups 2 and 4. Determination of regional
cerebral glucose utilization (rCGU) was carried out using the
[3H]2-deoxyglucose method, and regional cerebral blood flow (rCBF) was
determined by the indicator fractionation method using [14C]iodoantipyrine.
The brain regions studied were the cerebral hemispheres, the diencephalon,
the cerebellum, and the brainstem. Hyperventilation in Groups 2 and 4 from
approximately 38 to 22 mm Hg reduced rCBF to 60% of normocarbic levels (p
less than 0.05). The slope and intercept of this response were similar in
vehicle- and nimodipine- pretreated rats. Nimodipine modestly decreased
mean arterial blood pressure by 20% and increased plasma glucose
concentration by 60% (p less than 0.05). Although nimodipine tended to
increase rCBF and decrease regional cerebrovascular resistance (rCVR), this
was significant only for hemispheric rCVR (p less than 0.05). There was a
borderline effect for nimodipine to increase rCGU, especially during
hypocarbia.(ABSTRACT TRUNCATED AT 250 WORDS)