AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 6 1126-R1130, Copyright © 1990 by American Physiological Society
Fetal catecholamine responses to maternal hypoglycemia
C. M. Harwell, J. F. Padbury, R. S. Anand, A. M. Martinez, E. Ipp, S. L. Thio and E. E. Burnell
Perinatal Research Laboratories, University of California, Los Angeles Harbor Medical Center, Torrance 90509.
The present studies were designed to determine the fetal catecholamine and
metabolic responses to insulin-induced maternal hypoglycemia. Maternal
hypoglycemia was induced by a primed constant infusion of insulin and
glucose administered to pregnant ewes to maintain maternal glucose at 20-25
mg/dl. Maternal and fetal samples for measurement of catecholamine,
glucose, and free fatty acid levels and arterial blood gas analysis were
collected before insulin infusion and at intervals thereafter for 6 h.
Maternal and fetal plasma catecholamine levels increased significantly in
response to hypoglycemia (analysis of variance, P less than 0.01). Fetal
insulin and glucagon levels did not change despite a 50% reduction in fetal
whole blood glucose concentration. Fetal free fatty acid levels increased
significantly during hypoglycemia (P less than 0.05). There were no
significant changes in maternal or fetal heart rate, blood pressure, or
arterial blood gases during hypoglycemia. These results suggest that the
fetus is capable of responding to hypoglycemia with an increase in
catecholamine and free fatty acid levels. These results are consistent with
the interpretation that the fetus is able to mobilize alternative energy
substrates in response to maternal insulin-induced hypoglycemia.
