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.