FIBRINOGENOLYSIS AND FIBRINOLYSIS WITH STRENUOUS EXERCISE

Twenty healthy young men were exercised on a treadmill according to the protocol of Balke and Ware. Mean duration of exercise was 24.9 ± 5.7 min and mean maximum heart rate was 195 ± 9. Fibrinolytic activity was markedly accelerated with euglobulin lysis times decreasing to 36% of control values and fibrinogen-fibrin degradation products increasing 109% after exercise. Assays for fibrin monomer were negative in all samples. In vivo fibrinogen Aα-chain degradation was assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis of reduced samples of fibrin monomer isolated by clotting plasma samples in the presence of 0.1 M ε-aminocaproic acid and 1% disodium ethylenediaminetetraacetate. The Aα-chain, the fibrinogen chain most susceptible to plasmin degeneration, showed no evidence of increased degeneration after exercise. Gel scans showed no decrease in the ratio of total α-chain to β- and γ-chains after exercise. The ratio of intact α1 chain (α1, 67,000 mol wt) to total α-chain was 0.66 ± 0.13 before exercise, 0.64 ± 0.14 immediately after exercise, and 0.65 ± 0.13 1 h after exercise. The rate and extent of cross-linking of the α-chain of fibrin formed by clotting plasma samples was unaltered by exercise. These data suggest that physiologically significant fibrinogenolysis does not occur with strenuous exercise, even when fibrinolytic activity is markedly accelerated.