ABSTRACT
The plasma disappearance curve following a single intravenous injection of a tracer dose of 131I-labelled Rose Bengal (131I RB) is used to calculate the parameters of a three-compartmental model. In the model proposed, plasma 131I RB exchanges with two additional pools, one of which is thought to represent extrahepatic extravascular compartment (compartment 2) and the other the liver (compartment 3). 131I RB is assumed to be eliminated from the system solely from compartment 3 by secretion into bile, and no urinary excretion is taken into consideration. The assumptions implicit in the model (no excretion of 131 I RB in urine, reflux from liver to plasma, exchange with extravascular extraphepatic compartment, identification of compartments 2 and 3 respectively as extravascular extrahepatic, and intraphepatic) are supported by a set of experimental data.
Subject(s)
Rose Bengal/metabolism , Bile/metabolism , Humans , Iodine Radioisotopes , Kinetics , Liver/metabolism , Models, Biological , Rose Bengal/blood , Rose Bengal/urine , Scintillation CountingABSTRACT
Scintigraphic imaging of the hepatobiliary system has been significantly improved with the development of 99mTc-labeled compounds. Two of the most promising agents, pyridoxylideneglutamate and HIDA, each formed the basis for the development of a group of structural analogs. Condensation of pyridoxal with leucine and arginine (in place of glutamate) produced pyridoxylideneleucine and pyridoxylidenearginine. Since increasing the molecular weight and the lipid solubility of compounds tends to enhance their biliary excretion, several new IDA derivatives were synthesized by altering the lipophilic substituents on the ring of HIDA. The substitutions included ethyl and ethoxy groups as well as iodine. All compounds were compared with 131I-rose bengal using a baboon model that allowed blood, bile, and urine collection.
