DIFFERENTIAL-EFFECTS OF ALCOHOLS ON INTRACEREBRAL ARTERIOLES - ETHANOL ALONE CAUSES VASOCONSTRICTION

We compared the effect of the acute application of ethanol, methanol, 1-propanol, 1-butanol, urea, and mannitol (1-100 mM) on the basal tone of isolated-cannulated rat intracerebral arterioles to determine if t he response of these arterioles to ethanol could be attributed to alte ration of membrane fluidity or changes in osmolality. These arterioles spontaneously developed tone to 62.0 +/- 8.4% of passive diameter (44 .2 +/- 11.9 vs. 70.9 +/- 14.7 mu m) Ethanol caused a dose-dependent re duction in arteriolar diameter starting at 3 mM (p = 0.03), reaching a diameter of 81.4 +/- 3.0% of basal tone at 100 mM. In comparison, all other agents tested caused the arterioles to dilate, with the excepti on of 1-propanol, which produced inconsistent vessel responses. At 100 mM concentration, methanol, 1-butanol, urea, and mannitol dilated int racerebral arterioles by 116.1 +/- 12.7, 151.5 +/- 12.4, 131.1 +/- 17. 0, and 149.8 +/- 6.6%, respectively. Thus, in a concentration range as sociated with acute intoxication, ethanol causes constriction of isola ted intracerebral arterioles. The mechanism of action of ethanol canno t be accounted for sorely based upon its physicochemical characteristi cs of osmolality or lipid solubility, but rather may reflect a more sp ecific action on one or more cellular mechanisms responsible for deter mining basal intracerebral arteriolar tone. The characterization of th e response of intracerebral arterioles to ethanol is important in view of epidemiologic links between ethanol consumption and cerebrovascula r disease.