PAI-1 synthesis and secretion. Evolution of plasma PAI-1 concentration (A) and secreted PAI-1 from tissue explants (B) in the three groups. A significant increase in secreted PAI-1 in either whole aorta (W) or medial ring (M) was observed in the l-NAME group. Correlations (C) between PAI-1 (plasma ◯ — and secreted◆…) and systolic BP in the l-NAME group (r = 0.85, p = 0.005 and r = 0.72, p < 0.05, respectively). The increase in plasma PAI-1 antigen level corresponded to a significant increase in PAI-1 mRNA expression (open bar) in the arterial wall (D). Nevertheless, t-PA mRNA expression (gray bar) was also significantly increased in the arterial wall of the l-NAME rats (D). Values are means ± SEM. *p < 0.05, **p < 0.01 versus controls. $$p < 0.005 versus l-NAME.