1979 Volume 16 Issue 6 Pages 556-568
A quantitative study for fibrinogen, fibrin (Fg) in intima-media samples were carried out on 47 human aortas aged 0-81yr (average 41.4) using single radial immunodiffusion method modified in our laboratory. 22 cases died of the various diseases and 25 cases died of accidents, in which 19 cases kept fluidity of their blood. Different small parts of intima-media were sampled after washing with 0.9% saline and classified macroscopically into 5 groups according to atherosclerotic severity (SC O-IV).
Soluble Fg antigen (Sol. Fg. A) was extracted from tissue samples by homogenation. Using supernate, unclottable and supernatant Fg antigens (U. Fg. A and Sup. Fg. A) were prepared by incubation with thrombin and thrombin-plasmin respectively. Sediments were incubated with plasmin to measure the insoluble Fg antigen (I. Fg. A). These antigens were subjected to immunoplate. Clottable Fg (C. Fg) and total Fg (T. F) were calculated from antigen values as follows; C.Fg=Sol.Fg-U.Fg, T.F=Sup.Fg+I.Fg. Results obtained were represented as mg/wet tissue g of equimolar fibrinogen.
C.Fg, I.Fg and U.Fg were found in all samples of normal intima-media, and mean values were 0.149±0.076, 0.408±0.223 and 0.138±0.155 respectively. C.Fg and I.Fg significantly increased with advancing atherosclerotic changes, while a highly significant increase was observed in I.Fg. C.Fg increased with aging, and there was a significant correlation between I.Fg and aging. On the other hand, there was no significant correlation between U.Fg and severity, and besides aging showed no influence on U.Fg levels.
In comparison between fluid and non-fluid blood cases, C.Fg and U.Fg were almost in the same in both groups, while in non-fluid groups significant increase of I.Fg was observed, postulating that one part of fibrin originates from deposited fibrin on luminal surface or mural thrombi.
No significant differences were found in Fg levels of samples from subjects in 3-12hr and 12-24hr postmortem. In addition, each Fg levels were in the same in both sex groups. Aging, nature of intravascular blood, sex and postmortem time showed no influence on the relationship between Fg and seventies.
From these findings, it is supposed that fibrinogen entering through arterial wall under the physiological condition would remain there in form of intact for a while and that increase of fibrinogen caused by increased endothelial permeability and by structural changes of arterial wall associated with aging process, which would cause the disturbance of passage, might play an important role in deposition of fibrin.