Anesthetic agents are often administered in the presence of ethyl alco
hol. both in research and in the clinical setting. The authors tested
the hypothesis that anesthetic agents may affect cerebrovascular respo
nses to ethanol. A closed cranial window preparation in the rat was us
ed to compare the response of pial arterioles to topically applied eth
anol (0.01% to 1% vol/vol) in the presence of alpha-chloralose/urethan
e (50 and 600 mg/kg, respectively) or halothane (0.5% to 1%) anesthesi
a. Heart rate, mean arterial blood pressure, and blood gas levels were
maintained stable and within the physiological range throughout each
experiment. Ethanol induced significant vasoconstriction in alpha-chlo
ralose/urethane-anesthetized animals (multivariate analysis of varianc
e (MANOVA), p = 0.039); conversely, ethanol induced significant vasodi
lation of the pial arterioles in halothane anesthetized animals (MANOV
A, p = 0.017). These responses were significantly different from one a
nother (MANOVA, p = 0.001). Thus, the choice of anesthetic agent alter
s the cerebrovascular response to ethanol, and care should be taken to
ascertain the influence of anesthesia in both research and clinical s
ettings.