Kinetics of XXXX efflux from isolated @entity35 hepatocytes.

@entity5303 @entity2041 @entity2197 @entity35 @entity5954
The characteristics and kinetics of @entity2041 ( @entity2197 ) efflux were examined in homogeneous suspensions of freshly isolated @entity35 hepatocytes. @entity2197 efflux was measured as its linear accumulation in the suspension medium. Appearance of @entity2197 extracellularly was reflected in a quantitative loss in cellular @entity2197 . However, the total @entity2197 remained essentially unchanged, indicating minimal net synthesis of @entity2197 under these experimental conditions. @entity2197 efflux was sensitive to temperature, with a calculated Q10 value of 2.3. A wide range of cellular @entity2197 concentration ranging from near complete and moderate depletion to severalfold the control values was achieved by treatment of animals or cells with various @entity2197 depletors or inducers. At physiological (fed) and elevated ( @entity5954 - and @entity5303 -induced) cellular @entity2197 , the rate of @entity2197 efflux was near maximum. The rate fell dramatically to 50% maximum at a @entity2197 concentration equaling 35 nmol/10(6) cells. A 48-h fast resulted in a 40% loss of cellular @entity2197 , with a corresponding decrease in efflux rates. Addition of @entity2197 to the incubation medium had no effect on efflux rates. The relationship of @entity2197 efflux to cellular @entity2197 concentration was characterized by apparent sigmoidal saturation kinetics. The data were fitted well by the Hill model with the following kinetic parameters: Vmax = 0.25 nmol X 10(6) cells-1 X min-1, Km = 3.5 mM, and n = 3. These results correspond very closely to our previous findings in the perfused liver.
