Masaaki Hazue

In vivo Behavior of 111In-DTPA in Rat and Mouse after Intra-Ventricular Administration

In vivo behavior of 111In-DTPA in rat and mouse after intra-ventricular administration was studied. Thus, 50 muCi and 35 muCi of 111In-DTPA was injected intra-ventricularly to rat and mouse respectively. At specific time intervals, the animals were sacrificed, then distribution in organs was determined by radioactivity counting and autoradiographic method. Urinary and fecal excretion were separately collected and excretion rates were estimated. Metabolites in urine of rat were examined with chromatography. A part of 111In-DTPA injected intra-ventricularly to the animals migrated to subarachnoid space, then radioactivity in cerebrospinal fluid effused into blood with about 1 hr initial half-life. Blood clearance was also rapid, about 1 hr after administration the blood level reached maximum and then decreased showing an initial half-life of about 1 hr. The predominant excretion route in rat was urinary and about 90% and 5% of administered dose were excreted within 48 hr through urine and feces respectively. Judging from the Rf-value of radioactivity peak on chromatograms, 111In-DTPA seems to be excreted without suffering any metabolic change. Concerning to the behavior of 111In-DTPA in male and female rat, no difference was observed, and the distribution pattern of 111In-DTPA in mouse was similar to that of rat.