Release of prostacyclin from the human aorta

Prostacyclin (PGI₂) release by human aortic tissue obtained at surgery was assessed in patients (n = 23) with ischaemic heart disease undergoing coronary artery bypass grafting (group 1) patients (n = 14) undergoing surgery for aortic stenosis (group 2), patients (n = 4) undergoing surgery for aortic regurgitation (group 3), and patients (n = 8) with ischaemic heart disease taking aspirin (group 4). Although there was a highly significant correlation between (a) intimal and medial PGI₂ production and (b) medial PGI₂ production and aortic diameter, there was no correlation between intimal PGI₂ production and aortic diameter. Aspirin intake (75-150 mg daily) was associated with a pronounced inhibition (95%) of aortic PGI₂ production. This inhibition of aortic PGI₂ secretion by aspirin may account for the variable efficiency of aspirin in altering the natural history of vascular disease.