| Abstrakt: |
Activities of phosphofructokinase (E.C. 2.7.1.11; PFK) and hexokinase (E.C. 2.7.1.1; HK) were determined fluorometrically in freeze dried sections of the uterus (Days 10–145) and placentomes (Days 80 and 145) from pregnant Merino ewes. Samples (0.2–0.3 μg) from the luminal epithelium, uterine glands, maternal caruncles, fetal cotyledons and intercotyledonary trophoblast were assayed for PFK and HK in an aliquot (5 μl) of the reaction medium under oil.Enzyme activity in the luminal epithelium and caruncles was higher than in the glands and fetal tissues. After an initial (10–15 days) significant fall (P<0.01) in PFK activity of the luminal epithelium, the activity of this enzyme in all structures remained constant until Day 80 of pregnancy, after which the activity increased significantly (P<0.01).Hexokinase activity in the luminal epithelium decreased significantly (P<0.01) on Day 15. On Day 80 the activity in the luminal epithelium and glands increased significantly (P<0.01); however, it decreased slightly (P<0.05) on Day 145. In the caruncles, the activity of this enzyme increased (P<0.01) progressively after Day 30.In the fetal cotyledons and trophoblast, the activity of PFK was constant between Days 80–145, but HK activity decreased (P<0.05). During the second half of pregnancy these enzymes were 2–6 times more active in the maternal caruncles than in the other structures.These results suggest that after implantation, particularly during the second half of pregnancy, the rate of glycolysis is increased to meet the increasing energy demand of the growing fetus. The results are discussed in relation to fetal metabolism and histotroph production during pregnancy in the sheep. |
