Effect of simultaneous Tc-99m diethyl-IDA and sulfobromophthalein administration on liver excretory function in rats.

Competition of diethyl-IDA and BSP during their synchronous passage through the liver was examined on an animal model. Rats were divided in three groups, according to the amount of diethyl-IDA or BSP administered. No significant influence of diethyl-IDA on the liver uptake of BSP was noticed compared to the controls, while BSP demonstrated a significant inhibitory effect on diethyl-IDA plasma-activity decrease. On the biliary pole of hepatocyte, a reciprocal inhibitory influence of both compounds was present, with significantly diminished biliary excretion of both BSP and diethyl-IDA. As the input of BSP was not decreased, there evidently appeared a storage of BSP within the liver. A mathematical model of both plasma and bile changes of the concentration (or activity) of these compounds was also proposed. For the vascular compartment the model is correct, while biliary excretion of diethyl-IDA is significantly changed in presence of BSP and the satisfactory fit cannot be easily obtained.