Technetium 99m labelled heparin: pharmacokinetics and tissue distribution in rats after vascular surgery.

Pharmacokinetics of technetium 99m (99mTc) labelled heparin was studied after I.V. infusion (70 IU/kg) in normal rats and in a group of animals just after aortic longitudinal incision and suture. Anticoagulant activity measurements and radioactivity were compared on the same plasma samples. The pharmacokinetic decay of 99mTc-heparin followed a bi-exponential pattern. Half-lives (T1, T2) were significantly shortened after surgery using both techniques. Liver accumulation of labelled heparin was decreased in "sutured" rats and a high uptake of 99mTc-heparin was found on the operated area of the aorta.