Tissue plasminogen activator (tPA) promotes fibrinolysis and impaired fibri
nolysis is associated with atherosclerosis and thrombosis. Plasminogen acti
vator inhibitor-1 (PAI-1) inhibits t-PA expression. The effects of acute la
boratory stressors on tPA and tPA/PAI-1 complexes were assessed in a sample
of 11 cardiac patients. Participants were randomly assigned to either a st
ress or relaxation condition at time 1, and the alternative condition at ti
me 2. Blood samples were taken before (pre) and after (post) each session a
nd participants completed a battery of psychological questionnaires. Two-wa
y repeated-measures analysis of variance revealed a statistically significa
nt decrease in tPA (P = 0.01) and tPA-PAI-1 complexes (P = 0.04) during the
mental stress condition. Anger-in had a strong relationship to decreases i
n tPA/PAI-1 levels in the stress condition (r = 0.68, P < 0.05). Relaxation
had no significant effect on tPA and tPA/PAI-1 levels. These data suggest
that decreased fibrinolysis mediates the relationship between mental stress
and atherosclerosis.