Effect of acute umbilical cord compression on hepatic carbohydrate metabolism in the fetal lamb.

Abstract

Although the liver plays a central role in glucose homeostasis in the adult, its importance in fetal glucose homeostasis during acute reductions of substrate delivery is unknown. To examine this, we studied eight fetal lambs at 121 +/- 2 d gestation. We placed catheters in the descending aorta, inferior vena cava umbilical vein and the left (n = 6) or right (n = 2) hepatic vein, and a balloon occluder around the umbilical cord. At least 4 d after surgery, before and during umbilical cord compression, we measured blood oxygen saturation, glucose, lactate, and Hb concentrations, and blood flows using the radiolabeled microsphere technique. Gluconeogenesis was assessed by infusion of [U14C]lactate. Reducing umbilical flow by 50-60% from a control value of 181 +/- 20 mL/min/kg (mean +/- SD) caused a dramatic decrease in hepatic blood flow from 332 +/- 99 to 94 +/- 77 mL/min/100 g (p less than 0.05). Oxygen delivery to the fetus fell by 50% and that to the liver by 73%. However, hepatic O2 consumption was maintained by increased extraction. Glucose delivery to the liver fell from 67 +/- 24 to 20 +/- 13 mg/min/100 g (p less than 0.001), but lactate delivery did not change. In spite of the maintenance of lactate delivery, net hepatic lactate uptake fell significantly from 3.3 +/- 1.7 to 1.4 +/- 0.9 mg/min/100 g (p less than 0.05). This could account, in part, for the increase of blood lactate concentration from 16 +/- 4 to 27 +/- 7 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)