title: Isolated rat hepatocyte couplets: a primary secretory unit for electrophysiologic studies of bile secretory function.
abstract: Hepatocyte couplets were isolated by collagenase perfusion from rat liver. Between adjacent cells, the bile canaliculus forms a closed space into which secretion occurs. As in intact liver, Mg2+-ATPase is localized at the canalicular lumen, the organic anion fluorescein is excreted, and secretion is modified by osmotic gradients. By passing a microelectrode through one cell into the canalicular vacuole, a transepithelial potential profile was obtained. In 27 cell couplets the steady-state intracellular (-26.3 +/- 5.3 mV) and intracanalicular (-5.9 +/- 3.3 mV) potentials were recorded at 37 degrees C with reference to the external medium. Input resistances were determined within the cell (86 +/- 23 M omega) and in the bile canalicular lumen (32 +/- 17 M omega) by passing current pulses through the microelectrode. These data define electrical driving forces for ion transport across the sinusoidal, canalicular, and paracellular barriers and indicate ion permeation across a leaky paracellular junctional pathway. These findings indicate that the isolated hepatocyte couplet is an effective model for electrophysiologic studies of bile secretory function.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001646:Bile / Q000378:metabolism*; D001648:Bile Canaliculi / Q000502:physiology*; D001653:Bile Ducts, Intrahepatic / Q000502:physiology*; D017301:Ca(2+) Mg(2+)-ATPase; D002478:Cells, Cultured; D004553:Electric Conductivity; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008564:Membrane Potentials; D051381:Rats
chemical_list: D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase