A liposomal MRI contrast agent: phosphatidylethanolamine-DTPA.
The chelating agent, diethylenetriaminepentaacetic acid (DTPA), was attached via one -COOH group to the amino headgroup of phosphatidylethanolamine to produce a phospholipid which is also a powerful chelating agent. It readily assembles into the walls of lipid bilayer structures as a liposome-associated carrier of cations for MR contrast or radioisotope studies. Freeze-etch electron microscopy showed that phosphatidylethanolamine-DTPA formed satisfactory sonicated vesicles when mixed with natural phospholipids at up to 50 wt%. The resultant structures with bound gadolinium effectively shortened T1 and T2 of surrounding water protons. When sonicated liposomes bearing chelating agent with bound 111In3+ were injected intravenously into rats, uptake was primarily by liver and spleen. By 24 h postinjection there was biliary excretion of this material. Phosphatidylethanolamine-DTPA may have some general utility as an amphiphilic liposomal chelating agent for polyvalent cations.
Department of Biochemistry, University of Western Ontario, London, Canada.
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Grant
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Karlik
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Florio
D000818:Animals; D002614:Chelating Agents / Q000493:pharmacokinetics; D003287:Contrast Media / Q000493:pharmacokinetics; D005069:Evaluation Studies as Topic; D005682:Gadolinium / Q000493:pharmacokinetics; D008081:Liposomes / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008279:Magnetic Resonance Imaging; D004369:Pentetic Acid / Q000493:pharmacokinetics; D010714:Phosphatidylethanolamines / Q000008:administration & dosage / Q000493:pharmacokinetics; D051381:Rats
D002614:Chelating Agents; D003287:Contrast Media; D008081:Liposomes; D010714:Phosphatidylethanolamines; C007510:1,2-dipalmitoyl-3-phosphatidylethanolamine; D004369:Pentetic Acid; D005682:Gadolinium