Aspirin Acts on Blood Vessels to Prevent Heart Attacks

This activity is in addition to aspirin's blood thinning ability. The report was published May 13, 2002, in the online edition of Circulation.

"Aspirin is widely used to prevent heart attacks and strokes, but it is assumed that its effects are solely attributable to its blood-thinning actions. But our research turns the clock back on aspirin, and suggests that some of aspirin's effects really are due to its anti-inflammatory properties, which people have known about for 100 years or more,” says Dr. Patrick J. T. Vallance, professor of clinical pharmacology at University College (London, UK; www.ucl.ac.uk).

Investigators used a typhoid vaccine to cause inflammation in 17 healthy volunteers to determine if aspirin would prevent changes to blood vessel function. Twelve of these people received either 1.2 g of aspirin or a placebo two hours before vaccination. The remaining five patients received aspirin after the vaccination.
Interluekin-1 (IL-1) levels were measured to monitor the level of inflammation. In the placebo group, IL-1 peaked at three hours and remained elevated until eight hours after vaccination. This corresponded to a 30-fold increase in baseline values. In the group treated with a single oral dose of aspirin before the vaccine, the concentration of IL-1 did not differ from baseline.

Next, the researchers measured endothelial function by infusing drugs that affect the endothelium into the artery of one arm and then measuring blood flow. The six participants who received a placebo had decreased forearm blood flow eight hours after vaccination compared to baseline, indicating a temporary stiffening of their blood vessels. However, the six who received aspirin showed an increase in forearm blood flow eight hours after vaccination, indicating a protective effect from aspirin.

Dr. Vallance summarized the research by saying, "There is an exciting opportunity to rethink how we use aspirin and whether there are situations in which we should be giving aspirin to reduce cardiovascular risk.”




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