Metabolic effects of the delay in obliteration of the umbilical cord in the newborn rat.

The effect of delay in obliteration of the umbilical cord on the time-courses of liver glycogen, blood glucose and lactate concentrations and blood PO2, PCO2 and pH during the first 6 h of extrauterine life were studied. Obliteration of the umbilical cord 2 h after delivery resulted in an increase in liver glycogenolysis without significantly affecting the other parameters studied. A 6-hour delay in obliteration of the umbilical cord increased lactiacidemia and decreased blood PO2 and pH without significantly affecting the other parameters studied. A supply of pure oxygen to the newborns decreased lactiacidemia and increased PO2, although the differences between obliterated and nonobliterated newborns remained. These results suggest that hypoxia due to the persistence of placental circulation results in an increase in lactiacidemia as a consequence of a decrease in lactate utilization.