Uptake of 3H-demethylphalloin by isolated hepatocytes in the presence of various concentrations of phalloin or phalloidin

Abstract

The uptake of trace amounts of ³H-demethylphalloin (³H-DMP) by isolated hepatocytes was studied in the presence of various concentrations of unlabeled demethylphalloin (DMP), of phalloin and of phalloidin. The addition of phalloidin (or phalloin) reduces the uptake of ³H-DMP more than the addition of the equivalent concentration of DMP. The error caused by dilution of ³H-DMP with phalloin or phalloidin is not constant and depends on the concentration of the unlabeled compound. The relative differences between the uptake of ³H-DMP in the presence of demethylphalloin and in the presence of either phalloin or phalloidin cannot be explained by a competitive model. Some consequences for the use of ³H-DMP in toxicokinetic experiments are discussed.