The Pharmaceutical Journal Vol 264 No 7083p244
February 12, 2000 Clinical
The reason why people sometimes pass out when they overindulge in alcohol is because alcohol inhibits the reflex feedback mechanism that constricts blood vessels when the person stands up, according to researchers from the University of Iowa, Minnesota, US.
In tests on 14 healthy young adults, Dr Krzysztof Narkiewicz et al found that, during alcohol-free sessions, the subjects' blood vessels constricted normally and blood pressure did not change to any great extent on standing. However, blood pressure was lowered significantly after alcohol intake. After drinking the equivalent of two or three beers, the subjects' blood vessels failed to constrict and their blood pressure dropped up to twice as much on standing as it had when no alcohol had been ingested.
The authors state that this is because alcohol interferes with the reflex vasoconstrictor response to orthostatic stress, even at mild levels of intoxication. They comment that responses may vary in habitual drinkers or in patients with pre-existing impairment of orthostatic responses, such as the elderly (Circulation 2000;101:398).
Citation: The Pharmaceutical Journal URI: 20000434
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