LACTATE(L) AND FRUCPOSE(F) ARE GLYCOGENIC PRECURSORS IN THE CHRONICALLY CATHEPERIZED BABOON FETUS

In order to assess the contribution of the direct [phosphorylation(P) of glucose] vs indirect [P of other precursors) pathway of glycogenesis in the fetus(fet), ten baboon fet of 140 d gestation were studied after placement of femoral artery (FA) and umbilical vein(UV) catheters. On day 4 post surgery, after a 24h fast, maternal(mat) baboons were sedated and mat plasma glucose(G) was raised to 68±3 mg/dl with 10%G to mat vein. A primed dose of 50 uc/h U-14C L and 2-3H G (n=5), or U-14C F and 3-3H G(n=5) was infused to steady state into the UV over 3h. Six FA samples were obtained 90-180 min, the fet was sacrificed under mat-fet general anesthesia, and kidney and liver removed for determination of glycogen (gly) and 14C, 3H gly enrichment. Fetal blood 14C G derived from L SA was 4.0±.5, 14C G from F SA was 11.0±1.5, 2-3H G SA was 42.0+2.5, and 3-3H G SA, was 35.0±5.(uc/mg(103). Organ gly SA was calculated as uc/mg(103): SA organ gly/SA G reflects the fraction of gly derived from label. 14C SA kidney gly/SA G was greater than 2-3H or 3-3H ratio for F and L fet(p