Studies on the carbohydrate metabolism of sheep. 5. The effect of hyperglycaemia and of insulin on the rate of extrahepatic glucose assimilation

Abstract

Significant increases in the arterio-venous glucose difference have not been observed constantly in sheep either during the hyperglycaemia which follows intravenous glucose injection or during the period in which the blood glucose is falling after insulin administration. It is suggested that the low rate of extrahepatic glucose assimilation at hyperglycaemic levels provides a partial explanation of the relatively slow rate of clearance of injected glucose from the general circulation of ruminants. Blood-glucose curves, obtained after direct administration of glucose into the abomasum, are discussed in the light of these findings, and it is concluded that the rate of glucose absorption from the intestine of the sheep is low compared with the rate in non-ruminants. It is suggested further that hexokinase activity in the extrahepatic tissues of the sheep is relatively low, and that the findings described are conditioned principally by the nature of carbohydrate digestion and metabolism in the ruminant.