Some factors affecting the passage of insulin into bile in the rabbit, with some observations on glucagon

Abstract

In anaesthetized rabbits the concentration of insulin in hepatic duct bile is about the same as in hepatic portal blood plasma, and about 50% higher than in plasma from the inferior vena cava. About 20 min elapses between a peak in the concentration of insulin in blood (whether produced by intravenous injection of insulin or by stimulating endogenous insulin production with secretin or glucagon) and the corresponding peak in concentration in hepatic bile. Allowing for the conjectured dead space of the biliary tree, it seems that the time required for insulin to pass through liver cells must be about 17 min. ¹²⁵I-labelled glucagon passes from blood to hepatic bile much faster. If bile flow is increased by giving sodium taurocholate, the insulin passing out in hepatic bile per unit time is also increased. Insulin does not affect bile flow, but there is a positive correlation between resting bile flow and the concentration of insulin in bile. Subsidiary observations are that glucagon reduces bile flow, and that the concentration of insulin in gall bladder bile is surprisingly high.