| Abstract: | The appearance of plasma 14C]glucose in the inferior cava vein after a pulse of 0.2 mmol of U-14C]L-alanine or U-14C]glycerol/200 g body wt given through the portal vein was studied in fed 21 day pregnant rats and virgin controls under pentobarbital anesthesia. In both groups values were much higher when U-14C]glycerol was the administered tracer than when U-14C]L-alanine, and they were augmented in pregnant versus virgin animals at 1 min when receiving U-14C]glycerol and at 2 min when receiving U-14C]L-alanine. 20 min after the tracers rats receiving U-14C]glycerol showed much higher liver 14C]glycogen and 14C]glyceride glycerol than those receiving U-14C]L-alanine. Radioactivity present in liver as 14C]glyceride glycerol was greater in pregnant than in virgin rats receiving U-14C]glycerol whereas radioactivity corresponding to 14C]fatty acids was lower in the former group receiving either tracer. At 20 min after maternal treatments fetuses showed lower plasma 14C]glycerol than 14C]alanine values but plasma 14C]glucose and liver 14C]glycogen values were much greater in fetuses from mothers receiving U-14C]glycerol than U-14C]L-amine. Besides showing the higher gluconeogenic efficiency in pregnant than in virgin rats, results indicate that at late gestation glycerol is used as a preferential substrate for both glucose and glyceride glycerol synthesis in liver. |
