A study of absorption of compounds from the rat biliary tree by retrograde intrabiliary injection (RII)

Absorption of compounds from the biliary tree of rats was studied by a retrograde intrabiliary injection (RII) technique. After RII of a number of compounds in volumes that exceeded the maximum distended capacity of the biliary tree, only that volume of RII solution which corresponded to biliary tree capacity remained therein. Furthermore, this latter portion of RII solution was absorbed by a first-order process when the duration of bile duct cannula occlusion was extended. Thus, the present study demonstrates that absorption of retrogradely injected compounds continues during occlusion. Since excretion of i.v. administered compounds into the biliary system was also shown to continue during occlusion, we propose in the present study a concept of bidirectional exchange of solute within the biliary tree during occlusion. As an additional finding, after RII and occlusion, a temporary increase in bile flow was obtained. If the occlusion duration was 3 minutes or less, the bile flow response was of sufficient magnitude to repay alomst exactly the volume of bile that would have been expected to be produced. If the occlusion was 6 and 9 minutes the increased magnitude of the bile flow response was not great enough to repary the larger bile volumes expected and underpayments of -48 and -96 mul were incurred.