Age-related increase of tissue plasminogen activator in healthy subjects and coronary patients: Increased basal release and diminished liver clearance

Age-related changes of tissue plasminogen activator (t-PA) antigen, t-PA activity and plasminogen activator inhibitor (PAI) activity were measured before and after venous occlusion of the arm for 20 min in a group of 72 post-myocardial infarction male patients and in 53 controls. Analysis of age subgroups ( 60 years) showed an age-progressive increase of basal t-PA antigen in both groups. Basal PAI activity increased slightly in the patients but remained unchanged in the controls, resulting in a significant difference between the patients and controls in the oldest age group. Multivariate regression analysis suggested that basal t-PA antigen, but not PAI activity, was associated with age. Post-occlusion values of t-PA antigen increased slightly with age in healthy subjects, but decreased in the patients, implying that the age-related increase of t-PA may be attributed to an increased basal release from the vascular wall in healthy subjects, but may also reflect a diminished liver clearance in certain patients.