Interactions of CSS for PAI-1 antigen and activity
Components of the Plg system reside on chromosomes CSS-5 (PAI-1), CSS-11 (α2-antiplasmin), and CSS-17 (Plg). As reported in Table 2, the A/J mice had increased Plg antigen, fibrinolytic activity, α2-antiplasmin, PAI-1 activity and fibrinogen when compared to B6 mice. In CSS-17 mice, the Plg antigen was also significantly (P = 0.015) increased (152 ± 6, n = 12) when compared to the B6 mice, but for CSS-5 and CSS-5 × 17, the Plg antigen was similar to values for the B6 mice. Fibrinolytic activity was not different in the CSS-5 or CSS-17 strains compared to the B6 mice. α2-antiplasmin was significantly (P = < 0.01) reduced in CSS-5 mice (142 ± 4 μg/mL, n = 5), significantly (P < 0.05) higher in the CSS-11 (201 ± 6, n = 8), but not different in CSS-17 or CSS-5 × 17 mice compared to the B6 mice.
PAI-1 antigen and activity were determined in the CSS with increased rebleeding times, CSS-5, CSS-11, and CSS-17 (Figure 6), the heterosomic, CSS-5F1, CSS-17F1, and double hetersomic, CSS-5 × 17. CSS-5, CSS-17, CSS-5F1, and CSS-17F1 generally had reduced PAI-1 antigen when compared to B6 mice. The reduced PAI-1 antigen was a dominant trait due to the fact that the values were similar in the homosomic and heterosomic CSS-5 and CSS-17. The CSS-5 × CSS-17 double heterosomic strains had values similar to the B6 and A/J parent strains. PAI-1 activity was significantly reduced in the CSS-5 and CSS-17F1 mice, but again in the CSS-5 × CSS-17 strain the value for PAI-1 activity was restored to the value of the B6 and A/J parent strains. The PAI-1 antigen (5.4 ng/mL ± 0.5, n = 7) and activity (170 U/mL ± 20, n = 6) in the CSS-11 mice was not different than for B6 mice.
Figure 6  PAI-1 in the CSS backcrosses. Panel A: Plasma PAI-1 antigen (ng/mL) and Panel B: Plasma PAI-1 activity (U/mL) were tested in heterosomic mice, (B6xCSS-5)F1 (5F1) and (B6xCSS-17)F1 (17F1) and doubly heterosomic mice for chromosomes 5 and 17 (5 × 17). Bars are the mean ± SEM of 5–18 mice. Statistical differences between B6 mice and CSS were determined with a t-test, and a Bonferroni correction was made to determine significance value (P < 0.01). Symbols indicate a significant difference between B6 values. *P < 0.01.