The utilisation of glycerol by sheep

Increased but steady concentrations of glycerol and glucose in carotid, jugular and portal plasma of sheep were obtained between 2·5 and 3·5 h after the second of two oral doses of glycerol (2 and 1 ml/kg body weight with a 6 h interval between) and the concentration of glycerol in portal plasma was greater than in the other vessels. During the last hour of a 35 h continuous infusion of [ 14 C] glycerol and [ 3 H] glucose, ie, between 2·5 and 35 h after the second dose of glycerol, specific radioactivity (SRA) of glycerol and of [ 14 C] and [ 3 H] glucose were measured in plasma obtained from the three previously mentioned sites in dosed and undosed sheep. Although in dosed sheep the SRA of glycerol in portal plasma was lower than that in jugular plasma, the difference was such that the SRA in jugular plasma could be used to calculate entry rates and the rate of production of glucose from glycerol. Mean (±SE) glycerol entry rate in four fed sheep increased from 9·2±1·2 to 62·7±0·9 mg C/min after a divided oral dose of glycerol. Mean glucose entry rate increased from 29·0±34 to 58·3±7·6 mg C/min. The amount of glucose which was derived from glycerol increased from 5·4±1·6 to 35·5±3·7 mg C/min. This increase accounted for the increase in total glucose entry.