午夜福利1000集合

EVERYTHING鈥橲 gone fuzzy, the room鈥檚 spinning and all too soon you鈥檝e hit the
floor. The effects of standing up after too many beers are familiar enough, but
what causes them?

Virend Somers, a cardiologist at the Mayo Clinic in Rochester, Minnesota, now
has part of the answer. He suspected that keeling over was linked to changes in
blood pressure. Standing up makes blood pressure drop, drunk or sober. In a
sober person, blood vessels immediately respond by constricting, which brings
the pressure back to normal and keeps the brain supplied with blood.

If alcohol blocked this reflex, Somers reasoned, the reduction in blood
supply to the brain might cause fainting. To test the effect of alcohol on the
reflex, Somers鈥檚 team asked 14 healthy volunteers to take a drink. At the first
session, the volunteers imbibed the quantity of alcohol in about three beers,
while on another day, they were given a non-alcoholic sweet drink only. An hour
after each drink, they were asked to climb into a vacuum chamber that caused
about the same drop in blood pressure as standing up.

The team found that without alcohol, the volunteers鈥� blood pressure corrected
itself, suggesting their blood vessels were constricting. But after alcohol, the
pressure didn鈥檛 recover. 鈥淭he vasoconstriction was completely eliminated,鈥� says
Somers. It鈥檚 not yet clear why the blood vessels don鈥檛 constrict. Perhaps the
nerve signal that goes from the brain to the blood vessels is somehow impaired
by alcohol. Or maybe the vessels ignore the signal, Somers suggests.