Evaluation of portal circulation in rats by rectal administration of 201Tl followed by intrasplenic injection of 51Cr-labeled microspheres

The heart-to-liver (H/L) uptake ratio in rats was determined 8 min after the rectal administration of ²⁰¹Tl. Apart from normal controls, three groups of rats were examined; these were composed of animals with induced (1) acute hepatic damage, (2) liver cirrhosis, and (3) partial portal-vein ligation. After the rectal administration of ²⁰¹Tl, ⁵¹Cr-labeled microspheres were injected into the spleen. The radioactivity of the removed liver, lungs, and heart was determined in a gamma-well scintillation counter, and the radioactivity of ²⁰¹Tl and the ⁵¹Cr-labeled microspheres was separately calculated using simultaneous equations derived from the results of a preliminary experiment. The H/L ratios (²⁰¹Tl) in the normal controls and the animals with acute hepatic damage were not significantly different; however, there was a positive correlation (P0.01) between the H/L ratio and the shunt index (⁵¹Cr microspheres) in three groups, i.e., normal controls, liver cirrhosis, and partial portal-vein ligation.