出版社：American Society for Biochemistry and Molecular Biology
摘要：The effect of a single glucose feeding upon the net inflow and outflow transport of plasma free fatty acids (FFA) has been studied in 75 unanesthetized rats. The animals were fasted for 22 ±2 hr; then 50 rats were refed 2 ml of 50% glucose by gastric intubation. At 0, 10-15, and 30-35 min after glucose refeeding, the rats were injected with palmitatel1-14C complexed to rat serum. The tracer dose included 131I-labeled albumin. Plasma FFA concentration, 131I concentration, and FFA-14C were measured at five time intervals after injection of the tracer dose. From these data the irreversible disposal rate, or net outflow transport , and the net inflow transport of plasma FFA were calculated. Estimations were based upon a special case of a general solution for measuring net inflow and outflow transport of a circulating metabolite. The general solution is independent of the number of compartments, how they are interconnected, the number of nonradioactive inflows, and where the inflows enter the system. Net inflow = net outflow transport = 7.6 μeq/min in the fasted state and 3.5 μeq/min in the new steady state that is reached 30-40 min after glucose refeeding. A very slight imbalance between the rates of net inflow and outflow transport could account for the rapid fall in plasma FFA concentration that results from a single glucose feeding. Theoretical and practical problems associated with studying inflow and outflow transport by means of the technique using a single injection of racer are discussed.
关键词：irreversible disposal rate ; inflow-outflow transport ; nonsteady state ; unanesthetized rats ; palmitate turnover
