Background: Low density lipoprotein is a major pathogenic pathway in atherosclerosis. Previous studies suggested that aspirin, a commonly prescribed drug in patients with atherosclerosis, when given a dose of 300 mg/ day may decrease LDL susceptibility to oxidative modification. However, the effect of the more common lower dose aspirin on LDL oxidation is not known.
Objective: To examine the effect of aspirin administration (low dosage) on the susceptibility of LDL to oxidative modification healthy volunteers.
Methods: Aspirin 75 mg was administered daily for 2 weeks to 10 healthy volunteers selected from the medical staff and students at the faculty of medicine. The main outcome measure was ex vivo oxidation of LDL by ultraviolet C irradiation or by peroxyl free redicals generated by AAPH (2,2’ -azobis 2-amidinopropane hydrochloride). The extent of LDL oxidation was determined by measuring the formed amounts of thiobarbituric-acid reactive substances, lipid peroxides and conjugated dienes.
Results: Following exposure to UVC irradiation there was a significant (p<0.01) increase (10.8%) in TBARS concentrations and a significant (p≤0.05) increase (5.4%) in PD concentrations in LDL withdrawn after aspirin treatment as compared to LDL withdrawn before aspirin treatment. Following incubation with AAPH there was a significant (p<0.05) increase (15%) in PD concentrations and a significant (p<0.05) reduction (10%) of the LDL oxidation lag time in LDL withdrawn after aspirin intake as compared to LDL withdrawn before aspirin treatment.
Conclusions: Aspirin treatment given to healthy volunteers at a dose of 75 mg/day increased the susceptibility of their plasma LDL to oxidative modification ex vivo. Our study provides, for the first time, in vivo evidence of pro-oxidative properties of aspirin already suggested by previous in vitro trials.