Effect of glucose load on the transport kinetics of palmitic acid in the human placenta: an in vitro study.

1. A paucity of data relating to free fatty acid (FFA) transport in the human placenta in non-steady state conditions prompted us to undertake the present study. 2. The transport kinetics of palmitic acid in non-steady state conditions have been investigated in vitro using human perfused placental lobules. The effects of varying glucose concentrations on maternal-foetal transport of the FFA were also investigated to mimic the hyperglycaemic states of human diabetic pregnancies. 3. National Cancer Tissue Culture medium diluted with Earle's buffered salt solution was used as the perfusate. [14C]-Palmitic acid, along with tritiated water as a reference, was injected as a bolus into the maternal arterial perfusate and perfusate samples were collected from the venous outflow for a period of 5 min. 4. The transport fraction (TF) of palmitic acid, expressed as percentage of the injected bolus, averaged 3.45 +/- 0.15% in five perfusions, representing 9.2 +/- 1.3% of the corresponding reference marker TF. Kinetic parameters, as well as TF indices of palmitic acid expressed in relation to the reference substance, did not differ significantly between perfusions with a physiological glucose load and those with hyperglycaemic concentrations of glucose of 27.8 and 55.6 mmol/L. 5. The present study shows that hyperglycaemia per se does not significantly alter palmitic acid transport kinetics in vitro in the human perfused placental lobule.