Quantitation of the three normally-occurring plasma fibrinogens in health and during so-called "acute phase" by SDS electrophoresis of fibrin obtained from EDTA-plasma.

Normal human plasma contains fibrinogens of different molecular weight. To quantitate these fibrinogens, plasma was clotted at pH 6.4 with 7.5 NIH U/ml thrombin in the presence of 8 mM EDTA. The clots were dissolved in 6.6 M urea and submitted to SDS electrophoresis on gels containing 3% polyacrylamide/0.5% agarose, and the fractions quantitated by densitometric scanning. The reproducibility of this method was high with variation coefficient 1.5%. Three main fibrinogen fractions were found: High molecular weight fibrinogen (HMW, mw 340 000), low molecular weight fibrinogen (LMW, mw 300 000) and LMW' (mw 280 000). In addition 5 weak bands could be seen. In plasma from 123 healthy subjects of both sexes, aged 1-93 years, HMW constituted 69.7% +/- 5.1, LMW 26.5% +/- 4.8 and LMW' 3.8% +/- 1.8 of the total fibrinogen. Women and older subjects displayed a small, but statistically significant reduction in the relative amounts of HMW (2-4%). Following surgery and extensive acute myocardial infarction the HMW/LMW ratio changed. The substantial increase in total fibrinogen regularly recorded was mainly due to HMW that reached maximal values after 3-4 days. LMW remained unchanged the first 2 days and then displayed a slight increase with a delayed maximum (8-11 days).