The effect of feeding on the concentration of glucose and insulin in the portal and atrial plasma in pigs

SUMMARY Pigs weighing 25–40 kg were fed either once or twice per day and glucose and insulin concentration in portal and right atrial plasma measured during a 24-h cycle. Feeding resulted in an immediate increase in both portal and atrial glucose concentration. Portal glucose concentration tended to show cyclical changes with the peaks ascending and descending progressively. Under both feeding treatments glucose was absorbed from the gut for 18–20 h/day. Feeding of pure starch resulted in a rise in portal plasma glucose concentration within 10 min, but feeding of pure casein had no effect. Portal insulin concentration increased immediately on feeding as did atrial insulin concentration, and under both feeding treatments portal and atrial insulin concentration followed a pattern similar to the corresponding glucose concentration. Feeding of pure casein was without effect on the concentration of insulin in either portal or atrial plasma.