XENOBIOTIC METABOLISM BY ISOLATED RAT SMALL INTESTINAL-CELLS

Abstract

A rapid method for isolation of cells from the small intestine of the rat resulted in a preparation where 95-100% of the cells excluded NADH or trypan blue. Isolated intestinal cells catalyzed the cytochrome P-450-dependent metabolism of benzo(a)pyrene [carcinogen], harmine, ethoxyresorufin and ethoxycoumarin. Isolation of intestinal cells 24 h after a single oral dose of 3-methylcholanthrene resulted in 25 to 45-fold increases in benzo(a)pyrene, ethoxycoumarin and ethoxyresorufin metabolism, whereas the rate of demethylation of harmine was doubled. Harmine metabolism led to the formation of harmol, which was subsequently conjugated with glucuronic acid. Very little sulfate conjugate was detected. Intestinal cells catalyzed glucuronidation of 1- and 2-naphthol at a linear rate for up to 1 h. Glucuronidation of 1- and 2-naphthol was saturated at 50 .mu.M, whereas a concentration of 800 .mu.M was necessary for saturation of harmol glucuronidation. Intestinal cells metabolized paracetamol to the glucuronide, sulfate, glutathione and Cysteine conjugates. The latter two are evidence of cytochrome P-450-dependent metabolic activation of paracetamol by intestinal cells.