Uptake of free choline by isolated perfused rat liver.

Abstract

The uptake of free choline by isolated perfused rat liver was characterized. A saturable uptake mechanism [Ka = 0.17 .+-. 0.07 mM (SD); Vmax = 0.84 .+-. 0.16 .mu.mol/min .times. g dry weight] and a nonsaturable mechanism (through which uptake is proportional to choline concentration in the perfusate) were identified. Most choline transported into hepatocytes was converted to betaine, phosphorylcholine or lecithin. Free choline accumulated within the intracellular space, suggesting that choline oxidase activity does not always limit choline''s uptake by the liver.