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Radiopharmaceutical Chemistry: RadiopharmacyRadiopharmacy Posters |
1 Nuclear Medicine, Aarhus University Hospital, Aarhus, Denmark; 2 Protein Chemistry Laboratory, University of Aarhus, Aarhus, Denmark; 3 Clinical Institute, University of Aarhus, Aarhus, Denmark
1323
Objectives: Lactadherin is a milk fat protein which binds to phosphatidylserine exposed on the outer surface of the cell membrane of cells undergoing apoptosis, with higher affinity than Annexin V. The aim of the investigation was to compare the kinetics of 99mTc-HYNIC-lactadherin and 99mTc-HYNIC-annexin V. It was done in pigs because of the similarity with the human kidney.
Methods: Seven pigs with a weight of about 20 kg were studied with either 99mTc-HYNIC-lactadherin (4 pigs) or 99mTc-HYNIC-annexin (3 pigs). Tracer kinetic studies were done by a combination of non-invasive scintigraphy and invasive catheterisation. Total plasma clearance was calculated as the ratio between injected amount of tracer and the area under the plasma curve. Renal extraction was assessed by catheterization of the renal vein as the relative arterio-venous concentration difference.
Results: Scintigraphy in pigs showed high liver uptake of lactadherin and high uptake of annexin V in the kidneys. The total plasma clearance was 63 ml/min for lactadherin and 14 ml/min for Annexin. Renal extraction of lactadherin was about 3% whereas the extraction of annexin V fell from 18 to 1% 2-120 min p.i.
Conclusions: 99mTc-HYNIC-lactadherin was mainly taken up by the liver in contrast to 99mTc-HYNIC-annexin V which was mainly taken up by the kidneys. These results combined with the apoptosis recognition ability of 99mTc-HYNIC-lactadherin makes this radiotracer a potential new imaging agent for apoptosis in different organs with an advantage to 99mTc-HYNIC-annexin V for imaging apoptosis in the kidneys.
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