PROSTAGLANDIN E(1) INCREASES BINDING OF I-123 LOW-DENSITY-LIPOPROTEINTO THE HUMAN LIVER IN-VIVO

Previous in vitro radioligand binding data have shown that prostagland in E(1) (PGE(1)) increases the number and the binding affinity of low- density lipoprotein (LDL) receptors of the human liver. Experimental d ata in normo- and hypercholesterolaemic rabbits have confirmed these f indings, showing a significant increase in LDL-binding to the liver in vivo after prolonged PGE(1) therapy. Methods: This study aimed to con firm the experimental and animal data in human in vivo. I-123-LDL bind ing to the liver was quantified in vivo in patients suffering from per ipheral vascular disease, seven of them with heterozygous familial hyp ercholesterolaemia (HC) and five with normal total plasma cholesterol, after PGE(1) administration (5 ng . kg(-1). min(-1), 6 h daily for 5 days/week for 5 weeks). LDL uptake by the liver was quantified by sing le photon emission computer tomography (SPECT). Results: The amount of LDL trapped by the liver in normocholesterolaemics (45.6%) was signif icantly higher than in hypercholesterolaemics (22.0%). PGE(1) induced an increase in liver LDL binding, which was more pronounced in HC (+ 3 8.2%) than in normocholesterolaemic patients (+ 8.11%).