Consumption of carbohydrates, amino acids and oxygen across the intestinal circulation in the fetal sheep.
Since large volumes of nutrient rich amniotic fluid are swallowed by the fetus, it has been suggested that intestinal digestion and absorption contribute significantly to fetal nutrition. To see if nutrients are being gained across the intestine, we measured blood flow and intestinal arteriovenous concentration differences of glucose, alpha-amino nitrogen, lactate, fructose and oxygen in eleven third trimester fetal sheep with chronically implanted vascular catheters. We found that in fetal blood circulating through the intestine nutrient concentration decreased significantly with arterio-venous concentration differences for glucose of 0.78 +/- 0.21 (SEM) mg/dl (P < 0.002), for alpha-amino nitrogen of 0.52 +/- 0.15 mg/dl (P < 0.005), for lactate of 0.68 +/- 0.24 mg/dl (P < 0.05) and for oxygen of 1.50 +/- 0.08 ml/dl (P < 0.001). Fructose concentration did not change. Blood flow to the fetal intestine averaged 89.92 +/- 7.16 ml/min and the intestine consumed 0.74 +/- 0.24 mg of glucose, 0.43 +/- 0.17 mg of alpha-amino nitrogen, 0.83 +/- 0.28 mg of lactate and 1.37 +/- 0.14 ml of oxygen per minute. Compared to previously published values for the umbilical uptake of nutrients the fetal intestine metabolizes about 4% of the glucose, 6% of the alpha-amino nitrogen, 13% of the lactate and 6% of the oxygen obtained across the umbilical circulation. Intestinal absorption does not appear to serve as a source of simple nutrients for the rest of the fetus, in fact intestinal metabolism extracts significant amounts of nutrients from fetal blood.
D000596:Amino Acids / Q000097:blood*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D005260:Female; D005632:Fructose / Q000097:blood; D006452:Hemoglobinometry; D007408:Intestinal Absorption; D007422:Intestines / Q000098:blood supply*; D007773:Lactates / Q000097:blood; D008431:Maternal-Fetal Exchange; D010100:Oxygen / Q000097:blood*; D011247:Pregnancy; D012756:Sheep
D000596:Amino Acids; D001786:Blood Glucose; D007773:Lactates; D005632:Fructose; D010100:Oxygen