Fibrinolysis as Related to the Urea Solubility of Fibrin^[*]

Summary

The in vitro experiments described in this report demonstrate that the rate of fibrinolysis as determined by both the spontaneous whole blood fibrinolysis test and the fibrin plate procedure is altered by variations in technique. The addition of calcium ion to the fibrinogen before clotting and the heating of fibrin resulted in similar decreases in fibrinolytic activity. Probably the same mechanism was involved, since both the addition of calcium and heating are known to cause the conversion of hydrogen-bonded fibrin to the sulfhydrylbonded form. The finding of both kinds of fibrin in spontaneously clotted whole plasma and in clots taken from the heart postmortem suggests that the type of fibrin bonding may influence the rate of removal of clots in vivo.

^* This work was aided by grants from the United States Public Health Service (No. N-5146), Eli Lilly and Company, the Alameda County Heart Associarion, the Sonoma County Heart Association, and the Mrs. William A. Hewitt-Deere Estate Donation.

^** Giannini Fellow in Medicine, 1959-1960.

• References

• 1 Lorand L, Jacobsen A, Fuchs L. E. Biogenesis of protein fibers: the clotting of blood plasma. in Sulfur in Proteins. Benesch R. and others, Eds. Academic Press, Inc; New York: 109 1959
• 2 Scheraga H. A, Laskowski Jr M. The fibrinogen-fibrin conversion. In: Advances in Protein Chemistry. Anfinsen Jr C. B. and others, Eds. Academic Press, Inc; New York: 1 1957
• 3 Bidwcll E, Farlane R. G Mac. Observations on fibrinolysis. Is the activity produced by exercise due to plasmin?. Biochem. J. 49: 13 1957;
• 4 Laki K. The polymerization of proteins: the action of thrombin on fibrinogen. Arch. Biochem. 32: 317 1951;
• 5 Goyan F. M. Conductometric studies of certain salts of penicillin. J. Amer. pharm. Ass. 38: 161 1949;
• 6 Morrison P. R. Preparation and properties of scrum and plasma proteins: some factors influencing the quantitative determination of fibrinogen. J. Amer. diem. Soc. 69: 2723 1947;
• 7 Kline D. L. The purification and crystallization of plasminogen (profibrinolysin). J. biol. Chem. 204: 949 1953;
• 8 Norman P. S. Effect of urea and methylaminc on plasmin. Proc. Soc. exp. Biol. N.Y. 96: 709 1957;
• 9 Norman P. S. Studies of the plasmin system: I. Measurement of human and animal plasminogen. Measurement of an activator in human serum. J. exp. Med. 106: 423 1957;
• 10 Astrup T, Müllertz S. The fibrin plate method for estimating fibrinolytic activity. Arch. Biochem. 40: 346 1952;
• 11 Fearnley G. R, Ferguson J. Presence of fibrinolytic activity in whole blood, masked by the clotting process. Clin. Sci. 17: 555 1958;
• 12 Ryan T. A. Multiple comparisons in psychological research. Psychol. Bull. 56: 26 1959;
• 13 Lassen N. Heat dénaturation of plasminogen in the fibrin plate method. Acta physiol. scand. 27: 371 1953;
• 14 Murray M. The solubility of fibrin clots of diverse origins in urea. Amer. J. Path. 33: 400 1960;