Alterations in Transfer and Lipid Distribution of Arachidonic Acid in Placentas of Diabetic Pregnancies

Placental tissue from nondiabetic term pregnancies and pregnancies complicated by maternal insulindependent diabetes mellitus (IDDM) was perfused in vitro to compare the transfer and lipid distribution of arachidonic acid (AA). Radiolabeled albumin-bound AA was administered into the maternal afferent circulation, and samples of fetal and maternal effluent were collected at 10-min intervals. Perfused placental tissue was collected at the end of each experiment. The effluent was analyzed for total radioactivity, and extracts were subjected to thin-layer chromatography for the assessment of radioactivity associated with various lipid fractions. Placental AA uptake was significantly increased in perfused tissue from diabetic pregnancies (0.88 vs. 1.72 nM · min⁻¹ · g⁻¹ in nondiabetic and IDDM, respectively; P < 0.01), as was AA transfer (0.22 vs. 0.42 ml/min in nondiabetic and IDDM, respectively; P < 0.01). However, transfer of the highly diffusible marker substance antipyrine was significantly reduced in IDDM placentas (1.79 vs. 2.49 ml/min in IDDM and nondiabetic, respectively; P < 0.01). Compared with nondiabetic placentas, incorporation of AA into triglyceride was significantly increased in both maternal and fetal effluents and in placental tissue from IDDM pregnancies, whereas the percentage of AA remaining unesterified was reduced in both placental tissue and fetal effluent. Incorporation of AA into phosphoglycerides was significantly reduced in placental tissue but increased in fetal effluent in placentas from IDDM pregnancies. The results of these studies suggest that transfer and lipid distribution of AA are significantly altered in placentas from IDDM pregnancies. These findings may be relevant to the increased incidence of abnormal fetal growth and development associated with IDDM pregnancies.