Studies On The Dynamics Of Antithrombin III During Heparin Infusion By Radioimmunoassay
A radioimmunoassay method for antithrombin III (ATIII) was developed in order to detect the AT III levels correctly in plasma and tissues and the effect of heparin infusion was investigated on rat using this method and 125I labeled ATIII. Rat AT III was purified from rat defibrinated plasma by heparin sepharose affinity chromatography and gel filtrations. This purified AT III was used for the preparation of specific AT III antiserum. Labeling of AT III with 125I was performed according to the method by Hunter and Greenwood. Plasma level of AT III were significantly decreased in the treated group with heparin for 6 hours, although significant difference was not observed in AT III contents in various organs. The behavior of i.v. injected AT III laveled with 125I in the normal control and treated groups proved the difference on the half life of AT III. Control group gave 52 hours and it was shortened in the treated group. The percent radioactivity per ml plasma after 6 hours of heparin infusion was 1.16±0.51, and 2.01±0.38 in the control group, and significant difference was observed (p < 0.05). On the contrary the percent dose radioactivity per g tissue wet weight was significantly increased in the liver, lungs, and large intestine on the heparin treated group. The decreased amount of the intravenously injected laveled AT III appears to be trapped and metabolized in the various organs mainly in the liver during heparin infusion. The decrease of plasma AT III levels on the patients treated with heparin may be explained from these experimental results.