Abstract
Summary
Alcohol, in large amounts, increases the blood flow to brains of man and other animals. To what extent blood flow to specific regions of the brain varies with smaller, nonanesthetizing doses has been the subject of the present study. A new radioisotopic method was employed which permitted the simultaneous measurement of blood flow to each of ten regions of the brain in unrestrained, unanesthetized animals as small as rats. Three doses of alcohol were used: a low dose causing no behavioral change, an intermediate dose causing lack of coordination but no loss of consciousness, and a high toxic dose producing anesthesia. The blood levels of alcohol causing various signs of intoxication were the same in rats and man. At the low dose, no changes were seen in brain blood flow. At the intoxicating dose slight, but insignificant, increases were seen in the basal ganglia, frontal cortex, and olfactory bulb, while hippocampal blood flow decreased. At the anesthetic dose, blood flow increased to the olfactory bulb and the brain stem and actually decreased slightly to the parietal cortex. Support of the depressed ventilation rate observed at this dose of ethanol restored the pCO2 and pO2 values to control levels but did not reverse the observed acidosis; cardiac output fell, signaling increased peripheral resistance. Under these circumstances, the flow of blood to all brain regions fell, most notably to the hippocampus, cerebellum, and parietal cortex. The effects of ethanol and pentobarbital are compared.
We are indebted to Dr. D. Knowlton for the analyses of blood levels of ethanol. This work was supported in part by a grant from The Licensed Beverage Industries and by Public Health Service Grant NB05526.
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