Intermittent umbilical cord occlusion in the ovine fetus: Effects on bloodglucose, insulin, and glucagon and on pancreatic development

OBJECTIVE: To determine whether repetitive umbilical cord occlusion resulti ng in fetal hypoxemia but not cumulative acidosis also affects fetal glucos e levels and the levels of the regulatory hormones insulin and glucagon, by altering glucose delivery and with repetitive insults by inducing fetal gl ucose production, thus possibly affecting pancreatic development. METHODS: Fifteen chronically catheterized fetal sheep were studied over 21 days. Umbilical cord occlusions (UCOs) (duration 90 seconds) were performed every 30 minutes for 3-4 hours each day. Fetal arterial blood was sampled at predetermined times on days 1, 9, and 18 for blood gases, pH, glucose, l actate, insulin, and glucagon. When animals were sacrificed, fetal pancreat ic tissues were collected for insulin immunostaining. RESULTS: Blood glucose decreased acutely with each UCO but showed a cumulat ive increase of approximately 30% over the course of each sampling day, Alt hough plasma insulin levels also increased over the course of sampling on d ays 9 and 18, plasma glucagon levels remained unchanged throughout the stud y. The percentage of pancreatic islet cells immunopositive for insulin, whi ch averaged 67%, was also unchanged in experimental compared with control a nimals. CONCLUSION: Umbilical cord occlusion during the latter part of pregnancy, w hich caused severe but limited hypoxemia, also resulted in acute decreases in blood glucose levels because of reduced exogenous glucose delivery and a cumulative increase in glucose in response to repetitive insults, possibly by inducing fetal glucose production, enhancing glucose delivery, or both. However, repetitive UCO as studied had minimal effect on plasma insulin le vels and no effect on glucagon levels or on pancreatic immunostaining for i nsulin, and thus had no evident effect on pancreatic development. (J Soc Gy necol Investig 2001;8:191-7) Copyright (C) 2001 by the Society for Gynecolo gic Investigation.