Transport and biotransformation of the new cytostatic complex cis-diammineplatinum(II)-chlorocholylglycinate (Bamet-R2) by the rat liver1

Abstract

Rat liver uptake and bile output of the cytostatic complex cis-diammineplatinum(II)-chlorocholylglycinate (Bamet-R2) were studied. Up to 100 μm, Bamet-R2 uptake by rat hepatocytes in primary culture followed saturation kinetics (Vmax = 0.65 ± 0.12 nmol/5 min per mg protein; KM = 45.2 ± 10.7 μm). Bamet-R2 uptake was lower than that of cholylglycinate (CG) but higher than that of cisplatin. Replacement of 116 mm NaCl by 116 mm choline chloride did not significantly reduce Bamet-R2 uptake. Addition of 500 μm CG, cholic acid, estrone sulfate, or ouabain to 50 μm Bamet-R2-containing incubation media inhibited Bamet-R2 uptake. No liver biotransformation of Bamet-R2 occurred, as indicated by HPLC analysis of bile collected from anesthetized rats after intravenous administration of the drug. Bamet-R2 uptake and secretion into bile by isolated rat livers exceeded those of cisplatin but were lower than those of CG. Differences between Bamet-R2 and CG were more marked for bile output than for liver uptake. Thus, higher Bamet-R2 than CG or cisplatin liver content was found. Co-administration of Bamet-R2 and CG revealed that CG induced a slight reduction in Bamet-R2 uptake and a marked inhibition in Bamet-R2 bile output. By contrast, Bamet-R2 had no effect on CG on either liver uptake or bile output. In sum, the present data indicate that Bamet-R2 is efficiently taken up and secreted into bile by the rat liver by mechanisms shared in part by natural bile acids.—Macias, R. I. R., M. J. Monte, M. Y. El-Mir, G. R. Villanueva, and J. J. G. Marin. Transport and biotransformation of the new cytostatic complex cis-diammineplatinum(II)-chlorocholylglycinate (Bamet-R2) by the rat liver.

Keywords

• bile acid
• cancer
• chemotherapy
• cisplatin
• glycocholate
• metal