[Coagulation of 125I bovine fibrinogen]

Bovine fibrinogen was labelled with 125I using the chloramine T method or the iodogen method and the clottability of the preparations was studied in vitro and in vivo. Three days after radioiodination the in vitro clottability was 82.3% (chloramine T) and 80.4% (iodogen), respectively. When the solutions were allowed to stand at 4 degrees C for 13 days, the in vitro clottability decreased to 70% or 60%, respectively; either preparation was practically unclottable after 25 days. The preparations were administered to rats three days following radioiodination. They showed the same elimination rate and, on thrombin infusion, the same clottability. 125I-labelled (chloramine T) bovine fibrinogen stored in solution at -20 degrees C for 38 days showed a clottability of 76%, the in vivo clottability was unchanged.