PLACENTAL VILLOUS GLUCOSE-METABOLISM AND HORMONE-RELEASE RESPOND TO VARYING OXYGEN-TENSIONS

OBJECTIVE: The effects of varying oxygen tensions on tissue metabolic behavior are not well understood, yet many intracellular pathways are influenced by them. In the placenta, optimal in vivo oxygen tension at the villous level is unknown. The purpose of this study was to determ ine effects of varying oxygen tensions on glucose metabolism and hormo ne release from perifused placental villous explants. METHODS: Placent as from term normal pregnancies (n = 8) were individually minced into villous fragments, placed into three parallel chambers for each placen ta, and continuously perifused for 6 hours with nonrecirculating mediu m aerated with either 0%, 20%, or 95% oxygen yielding mean oxygen tens ions of 76 mmHg, 167 mmHg, and 543 mmHg respectively Outflow medium wa s removed at regular intervals and compared to the inflow medium to de termine oxygen and glucose consumption as well as lactate, lactate deh ydrogenase, hCG, estradiol, and progesterone release. RESULTS: Oxygen consumption was directly proportional to oxygen tension. Glucose consu mption was lowest at low oxygen tension, while both lactate and LDH re lease were lowest at high oxygen tension. Both hCG and progesterone re lease rates were lowest at high oxygen tensions. Estradiol release dem onstrated a trend similar to that of the other hormones although thee was no statistically significant difference among the three different levels of oxygen tension. CONCLUSION: Varying oxygen tensions affect p lacental villous glucose metabolism and hormone release. Under lower o xygen tensions, glucose is metabolized through glycolysis rather than through oxidative phosphorylation and is associated with higher lactat e release. Exposure to higher oxygen tensions results in reduced hCG a nd progesterone release. Higher oxygen tensions may be associated with tissue toxicity. Copyright (C) 1997 by the Society for Gynecologic In vestigation.