Catalog Home Page

Metabolism of ketone bodies in pregnant sheep

Pethick, D.W. and Lindsay, D.B. (1982) Metabolism of ketone bodies in pregnant sheep. British Journal of Nutrition, 48 (03). pp. 549-563.

[img]
Preview
PDF - Published Version
Download (871kB)
Link to Published Version: http://dx.doi.org/10.1079/BJN19820140
*Subscription may be required

Abstract

1. A combination of isotope-dilution and arteriovenous-difference techniques was used to determine the significance of ketones to energy homoeostasis in fasted pregnant ewes.
2. There was incomplete interconversion of D(−) 3-hydroxybutyrate (3HB) and acetoacetate (AcAc) and therefore neither entry rate nor oxidation of total ketone bodies could be estimated by assuming circulating ketone bodies represent a single metabolic compartment. Total ketone body metabolism was satisfactorily summarized using a three-compartment model. In fasted pregnant ewes the mean entry rate of total ketones was 1 mmol/h per kg body-weight and of the ketones entering the circulation 87% were promptly oxidized to carbon dioxide accounting for 30% of the total COa production.
3. Ketone bodies are readily utilized by hind-limb skeletal muscle such that if completely oxidized, 18±4 and 48±3% of the oxygen utilized could be accounted for in fed and fasted pregnant ewes respectively. For both 3HB and AcAc there was a hyperbolic relationship between utilization and arterial concentration. The apparent Michaelis constant (Km) values were 0·55 and 1–42 mM respectively and the maximum velocity (Vmax) 2·9 and 5·6 mmol/h per kg muscle. The arterial concentration of AcAc is always below the Km value and this limits the utilization rate. The D(−) 3HB concentration, however, may surpass that required for maximum utilization and ketoacidosis may be a consequence of this.
4. A two-compartment model was used to analyse ketone body metabolism by hind-limb skeletal muscle. The results suggested substantial intercon version and production of AcAc and 3HB.
5. The pregnant uterus utilized 3HB which if completely oxidized accounted for 12±2 (fed) and 25±4 (fasted) % of its O2 consumption. At least 64% of the net 3HB utilized was oxidized. AcAc was not utilized in significant quantities.

Publication Type: Journal Article
Publisher: Cambridge University Press
Copyright: © The Nutrition Society 1982
URI: http://researchrepository.murdoch.edu.au/id/eprint/18763
Item Control Page Item Control Page

Downloads

Downloads per month over past year