Postnatally, glucagon acutely lowers plasma amino acid (AA) concentrations by stimulating hepatic AA catabolism, but its fetal actions remain unclear. This study tested whether a 2 h fetal glucagon infusion would stimulate hepatic AA catabolism and inhibit placental AA transfer. Late-gestation pregnant sheep (0.9 gestation) underwent surgical, vascular catheterization and received fetal glucagon (