Abstract: DTPA-c-myc antisense oligonucleotides is synthesized and labeled with ~(113)In~m.The stability of ~(113)In~m-DTPA-c-myc antisense oligonucleotides in saline and bovine serum and the inhibition of cell proliferation are studied.The labeling yield in the optimal conditions is 35%～40% and the radiochemical purity is more than 90% after purification.The radiochemical purity of ~(113)In~m-DTPA-c-myc is more than 94.0% for 48 h in saline,and(76.1%) for 48 h in serum.When the concentration of ~(113)In~m-DTPA-c-myc antisense oligonucleotides is 10 μmol/L(92.5 GBq/L),the inhibition rate reaches the highest.The inhibition rate of ~(113)In~m-DTPA-c-myc antisense oligonucleotides(radionuclide antisense-treated group),antisense oligonucleotides(antisense-treated group),~(113)In~mCl_3 solution(radionuclide-treated group),without oligonucleotides or ~(113)In~mCl_3 solution(control group) and c-myc sense oligonucleotides(sense-treated group)is 84.5%,69.3%,20.6%,15.2% and 0,respectively.The inhibition of radionuclide antisense-treated group is significantly higher than that of antisense-treated group(P<0.05),radionuclide-treated group(P<0.01) and control group(P<0.01),and the inhibition of antisense-treated group is significantly higher than that of sense-treated group(P<0.01). Which demonstrates that ~(113)In~m-DTPA-c-myc antisense oligonucleotides can inhibite the proliferation of porcine VSMCs in vitro.