Aim We used hdgehogs to study the effects of low density lipoprotein-receptor inhibitor on the metabolism of low density lipoprotein and lipoprotein(a)with 125iodine.Methods Low density lipoprotein receptor inhibitor,Lactoferrin and receptor associated protein were used to inject into the body of hedgehogs via the armpit vein 2minites before the 125 iodine low density lipoprotein or 125 iodine lipoprotein (a) were injected.The animals were put to death in 6 h,The radioactivity in the blood,liver,kidney,spleen,gall and adrenal were measured;Results Experiments showed that the low density lipoprotein receptor were inhibited by lactoferrin and receptor associated protein。 The concentration of low density lipoprotein were decreased over 11.7%～86.7%in respectively compared with control group. However, the takeup of lipoprotein (a) in organs had not been inhibit ed,on the contrary it increases the takeup of lipoprotein (a) by the lactoferrin and receptor associated protein.The value of increasing was about 40%～120%。ConclusionsThe results indicated that lipoprotein (a)lose the capability to bind low density lipoprotein receptor since the configuration of lipoprotein (a) was changed in binding apolipoprotein(a)with apolipoprotein B100 although the construction and composition were similar with low density lipoprotein that they all contain the apolipoprotein B 100.It was inferred that lactoferrin and receptor associated ated protein could activite other mechanism on the cell membrane and favoured the lipoprotein(a)into the cells.