| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Glucose clamp procedures were used to determine whether the slowing of fetal growth during the final third of gestation in overnourished adolescent ewes is due to a reduction in placental glucose transport capacity. Singleton pregnancies to a single sire were established by embryo transfer and thereafter adolescent dams were offered a high (n = 11) or moderate (n = 7) nutrient intake. Studies were conducted at 130 ± 0.5 days gestation. Uterine and umbilical blood flows were studied by the steady-state transplacental diffusion technique and glucose fluxes quantified by the Fick principle. To determine the relationship between the transplacental glucose gradient and umbilical (fetal) glucose uptake, studies were conducted with maternal arterial glucose clamped at 5 µmol ml-1 and fetal glucose at spontaneously occurring and two additional higher levels. Maternal body weight gain during gestation averaged 282 and 57 g day-1 for high- and moderate-intake dams, respectively. Total placentome weight (209 ± 23 vs. 386 ± 34 g) and fetal weight (3072 ± 266 vs. 4670 ± 196 g) were lower (P < 0.001) in high- than in moderate-intake groups. The growth-restricted pregnancies in the high-intake dams were associated with reduced uterine (P < 0.05) and umbilical (P < 0.02) blood flows and, in the non-perturbed state, the fetuses were relatively hypoxic (2.1 vs. 3.0 µmol ml-1, P < 0.05) and hypoglycaemic (0.90 vs. 1.31 µmol ml-1, P < 0.002). Linear regression analysis of umbilical glucose uptake at three steady-state uterine-umbilical arterial transplacental plasma glucose concentration gradients revealed that absolute placental glucose transport capacity was lower in high- than in moderate-intake dams (mean slope, 0.8 vs. 1.5 dl min-1, P < 0.05; and mean intercept, 1.84 vs. 3.40 µmol ml-1). However, glucose transfer capacity was not different between the two groups when expressed on a placental weight-specific basis. This confirms that the small size of the placenta per se is the major limitation to placental glucose transfer in the overnourished adolescent pregnant sheep.
This article has been cited by other articles:
|
|
 |
|
  P. M. Coan, E. Angiolini, I. Sandovici, G. J. Burton, M. Constancia, and A. L. Fowden Adaptations in placental nutrient transfer capacity to meet fetal growth demands depend on placental size in mice J. Physiol., September 15, 2008; 586(18): 4567 - 4576. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Ericsson, K. Saljo, E. Sjostrand, N. Jansson, P. D. Prasad, T. L. Powell, and T. Jansson Brief hyperglycaemia in the early pregnant rat increases fetal weight at term by stimulating placental growth and affecting placental nutrient transport J. Physiol., June 15, 2007; 581(3): 1323 - 1332. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Wu, F. W. Bazer, J. M. Wallace, and T. E. Spencer BOARD-INVITED REVIEW: Intrauterine growth retardation: Implications for the animal sciences J Anim Sci, September 1, 2006; 84(9): 2316 - 2337. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Wallace, T. R. H. Regnault, S. W. Limesand, W. W. Hay Jr, and R. V. Anthony Investigating the causes of low birth weight in contrasting ovine paradigms J. Physiol., May 15, 2005; 565(1): 19 - 26. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Redmer, R. P. Aitken, J. S. Milne, L. P. Reynolds, and J. M. Wallace Influence of Maternal Nutrition on Messenger RNA Expression of Placental Angiogenic Factors and Their Receptors at Midgestation in Adolescent Sheep Biol Reprod, April 1, 2005; 72(4): 1004 - 1009. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Wu, F. W. Bazer, T. A. Cudd, C. J. Meininger, and T. E. Spencer Maternal Nutrition and Fetal Development J. Nutr., September 1, 2004; 134(9): 2169 - 2172. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
