ALCOHOL LOWERS THE VASOCONSTRICTION THRESHOLD IN HUMANS WITHOUT AFFECTING CORE COOLING RATE DURING MILD COLD-EXPOSURE

Elevated blood alcohol levels are often seen in hypothermia and hypert hermia related deaths, leading to the belief that alcohol renders huma ns poikilothermic. We examined the core temperature (T-co) thresholds for sweating, vasoconstriction and shivering as well as core cooling r ates of seven subjects immersed in 28 degrees C water. On two separate days, subjects exercised on an underwater cycle ergometer to elevate T-co above the sweating threshold. They then rested and cooled until t hey shivered vigorously. Subjects drank orange juice (7 ml . kg(-1)) p rior to immersion during the control trial and 1 ml . kg(-1) absolute ethanol, added to orange juice in a 1:6 ratio, during the alcohol tria l. Mean blood alcohol concentration (breath analysis) was 0.097 +/- 0. 010 g% at the start of cooling and 0.077 +/- 0.008 g% at the end of th e cooling period. Alcohol lowered the vasoconstriction threshold by 0. 32 +/- 0.2 degrees C and elevated finger tip blood flow, but had no ef fect on thresholds for sweating and shivering or core cooling rate. Co nsidering these minor effects it is unlikely that moderate alcohol con sumption predisposes individuals to hypothermia or hyperthermia via im paired thermoregulation, but rather likely due to behavioral factors.