Effects of liver blood flow on hepatic uptake kinetics of galactose in anesthetized cats: parallel tube model.
Hepatic galactose uptake in cats anesthetized with pentobarbital was determined during (i) steady-state infusions at several doses, (ii) rapidly increasing infusion rates at different blood flows, and (iii) prolonged infusion of a single dose at different blood flows. The hepatic venous long-circuit technique was used to allow frequent sampling of arterial, portal, and hepatic venous blood without depletion of the animal's blood volume and to allow measurement and alteration of total hepatic blood flow. Uptake was shown to follow Michaelis-Menten kinetics and was consistent with the "parallel tube model." The kinetic parameters Vmax and Km could be determined under steady-state and nonsteady-state conditions and were independent of hepatic blood flow over the range 60-150% of control flow. Mean Vmax was 80 mumol/(min X 100 g liver) and mean Km was 215 microM. Vmax declined by 50% when flow was reduced to half normal. It is concluded that the parallel tube model can be used to describe and predict hepatic galactose kinetics in anesthetized cats, although other models may fit the data equally well.
D000818:Animals; D001692:Biological Transport; D001794:Blood Pressure; D002415:Cats; D005260:Female; D005690:Galactose / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008102:Liver Circulation; D008297:Male; D008954:Models, Biological; D012984:Software
D005690:Galactose