Kinetics of palmitic acid transport in insulin-dependent diabetic pregnancies: In vitro study

Backgound: The paucity of data relating to transport kinetics of free fatty acids (FFA) in pregnant diabetic women prompted the undertaking of the pre sent study. Methods: Transport kinetics of a model FFA, palmitic acid, have been invest igated in Type I diabetic pregnancies, using in vitro perfusion of isolated placental lobules. National Cancer Tissue Culture medium diluted with Earl e's buffered salt solution was used as the perfusate and control placental lobules were perfused for comparison. Results: In five Type I diabetic women, the palmitic acid transport fractio n (TF) averaged 5.6+/-0.42% of injected maternal bolus dose, representing 1 1.8+/-2.1% that of tritiated water used as reference. In control perfusions (n=5), the palmitic acid TF represented 10.2+/-1.3% of tritiated water TF. Differential transport rates of palmitic acid for 10, 25, 50, 75 and 90% o f efflux in fetal veins differed significantly from the corresponding value s for tritiated water in both study and control series. However, palmitic a cid transport rates for the various efflux fractions in the two series were not significantly different. For kinetic parameters, such as area under th e curve, clearance, elimination constant, time for maximum response, absorp tion rate and elimination rate, the values for palmitic acid in the diabeti c and control series also did not differ significantly. Conclusion: Transport kinetics of palmitic acid in Type I human diabetic pr egnancies in in vitro conditions do not differ significantly from those obs erved in normal pregnancies.