Effect of arterial-portal glucose gradients and phloridzin on bile glucose levels in perfused rat liver.

1. Bivascular perfused rat liver was used to study the effects of hepatic artery-portal vein glucose gradients and the effects of phloridzin on bile glucose levels. 2. Bile glucose levels were examined when glucose concentrations in the hepatic artery (HA) and portal vein (PV) inflows were equal. When the concentration of perfusate glucose was 10 mM, bile glucose remained stable at less than 0.075 mM; when perfusate glucose exceeded approximately 16.0 mM, bile glucose increased rapidly; when 1.6 microM phloridzin and 10.0 mM glucose were co-infused, phloridzin entered rapidly into bile and settled at a steady-state concentration of 0.45 +/- 0.04 mM, and bile glucose increased to 3.75 +/- 0.14 mM. 3. During perfusion of HA-PV glucose gradients such that HA glucose was higher than that in the sinusoids, bile glucose levels were increased compared with their levels when HA glucose was equivalent to that in the sinusoids. The converse was also demonstrated. 4. The results regarding phloridzin-sensitive glucose transport in the biliary tree of the rat were consistent with those documented in vivo. The finding that bile glucose levels altered in a manner parallel to that of the HA, although the total inflow remained unchanged, strongly indicated that HA glucose level, rather than that of the PV, performs an important role in control of bile glucose levels.