ABSTRACT
Unidirectional fluxes (influx and efflux) and the net flux of palmitate across the hepatocyte membrane were measured in the intact rat liver employing the multiple indicator dilution technique. At albumin concentrations in the range between 0.1 and 0.5 mM the influx rate was 2.3 times greater than that of the net flux. The rate of efflux was somewhat higher than the net flux, indicating that palmitate undergoes an exchange process across the liver cell membranes with efflux to the extracellular albumin site being significant. At. lower albumin concentrations, hower, the influx/net flux approached unit, implying that transport becomes a rate-limiting factor for metabolism
Subject(s)
Albumins/metabolism , Liver/metabolism , Palmitates/metabolism , Indicator Dilution Techniques , PerfusionABSTRACT
The multiple indicator dilution technique was used to investigate octanoate transport in the isolated, perfused rat liver. The form of the octanoate outflow profiles depends on albumin concentration. The steady-state intracellular octanoate concentration and the rate of uptake increase when the albumin concentration is decreased. At physiological albumin concentrations, the intracellular concentration of octanoate is only 7% of the extracellular concentration. Exchange between the intra-and extracellular space, however, is very rapid, irrespective of the albumin concentration and consequently exchange is not rate limiting for metabolism