Metabolism of urea in late pregnancy and the possible contribution of amino acid carbon to glucose synthesis in sheep

Title
Metabolism of urea in late pregnancy and the possible contribution of amino acid carbon to glucose synthesis in sheep
Publication Date
1970
Author(s)
Nolan, John
( author )
OrcID: https://orcid.org/0000-0001-7949-950X
Email: jnolan@une.edu.au
UNE Id une-id:jnolan
Leng, R
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Cambridge University Press
Place of publication
United Kingdom
DOI
10.1079/BJN19700095
UNE publication id
une:22159
Abstract
1. Metabolism of urea in non-pregnant and pregnant sheep (1–25 d from term) has been examined. Injections of (14C) urea were used to estimate urea entry rate, urea pool size and urea space in sheep given 1000g of a diet of equal parts of crushed oats and chaffed lucerne hay (day a) and in the same sheep 4 d after the ration had been reduced to 250 g (day b). 2. On both experimental days (a and b), mean pool size was greater (14% on day a, 29% on day b) and urea space was greater (54% on day a, 24% on day b) in pregnant animals than in non-pregnant animals; mean plasma urea concentrations were lower (35%) in the pregnant animals on day a but were not significantly different on day b. 3. The entry rate of urea was similar in all the animals on day a, but was significantly higher (34%) in pregnant than in non-pregnant animals on day b. There was a significant decrease in urea entry rate in both pregnant (33%) and non-pregnant (86%) animals on day b. 4. The rate of excretion of urea was lower (26% on day a, 35% on day b) in pregnant animals, indicating a higher (31% on day a, 40% on day b) rate of degradation of urea in the digestive tract of pregnant as compared with non-pregnant sheep. 5. Measurements of urea entry rate have been used to calculate the upper limit of amino acid deamination in pregnant and non-pregnant sheep, and this has been used as an indication of the potential availability of amino acid carbon for glucose synthesis. It is suggested that, at a maximum, amino acids may have contributed the carbon required for 63 g/d and 52 g/d of glucose on days a and b respectively.
Link
Citation
British Journal of Nutrition, 24(4), p. 905-915
ISSN
1475-2662
0007-1145
Start page
905
End page
915

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