Effect of acute maternal starvation on tyrosine metabolism and protein synthesis in fetal sheep
To determine the effects of acute maternal starvation on intrauterine growth, tyrosine concentration and specific activity values in plasma, intracellular free and protein bound pools were determined in catheterized ovine fetuses following an 8 h continuous infusion of L-(2,3,5,6 /sup 3/H) or L-(U-/sup 14/C) tyrosine into the ewe and fetus respectively at 115-125 days of gestation. From the kinetic data the rates of whole body and tissue fractional protein synthesis were calculated. Although placental protein synthesis was not significantly changed as a result of acute maternal starvation, fetal whole body protein synthesis was reduced from 63 g/d/kg in the fed to 25 g/d/kg in the starved condition. There was also a 10 fold reduction in the net placental transfer of tyrosine to the fetus in the starved ewes. In addition, a three fold increase was observed in the quantity of tyrosine used for oxidation by the fetuses of starved ewes, changing from 5.2% of tyrosine net utilization in the fed to 13.7% in the starved condition. Significant reductions in tissue fractional protein synthesis rates were also seen in the liver, brain, lung kidney and GIT tissues from 78, 37, 65, 45 and 71%/d respectively in the fed to 12, 10, 23, 22 and 35%/d in the fetuses of starved ewes. The data indicate that during acute maternal starvation the sheep fetus utilizes more tyrosine for oxidation and less for anabolic purposes which is reflected in a decrease both in whole body and tissue fractional rates of protein synthesis.
- Research Organization:
- Univ. of British Columbia, Vancouver
- OSTI ID:
- 5229359
- Journal Information:
- Growth; (United States), Vol. 4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FETUSES
GROWTH
PROTEINS
BIOSYNTHESIS
TYROSINE
METABOLISM
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
FOOD
LABELLED COMPOUNDS
NUTRITIONAL DEFICIENCY
PREGNANCY
REDOX REACTIONS
SHEEP
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMALS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DOMESTIC ANIMALS
HYDROXY ACIDS
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
REACTION KINETICS
RUMINANTS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques