Galactose, glucose, and lactate concentrations in the portal venous and arterial circulations of newborn lambs after nursing.

We have used the newborn lamb prepared with chronic indwelling catheters to study carbohydrate metabolism in the unstressed, postprandial state. Lambs were fasted 5 h and then allowed to nurse ad libitum from their mothers for 20 min. Serial determinations of whole blood galactose, glucose, and lactate concentration were then made from the portal venous and arterial circulations. Portal venous galactose concentration increased significantly after milk ingestion, but arterial galactose concentration did not increase from baseline unless the portal venous galactose concentration exceeded 10-12 mg/dl suggesting a threshold effect for hepatic galactose clearance. Glucose concentration increased significantly in both circulations with portal venous galactose concentration greater than arterial galactose concentration in all cases. Galactose and glucose were absorbed from the intestine at approximately equal rates. Lactate was not absorbed into the portal venous circulation to any great extent after lactose ingestion.