Microscopic fluorometric analysis of Na-fluorescein transport in the smallest secretory unit (couplet hepatocytes) and the effects of cytochalasin B.

: The uptake and secretion of sodium fluorescein by couplet hepatocytes was examined in primary culture. When sodium fluorescein was added at an early stage of primary couplet hepatocytes culture, this resulted in a rapid uptake of the dye and its subsequent accumulation in bile canaliculi. From microscopic fluorometry observations, cytochalasin B pretreatment of the couplet hepatocytes caused much more rapid uptake and secretion of the dye in bile canaliculi. The present study indicates that the cholestatic agent cytochalasin B causes choleresis at the bile canalicular level of cultured couplet hepatocytes and also indicates that a defect in canalicular secretion plays no role in the cytochalasin B-induced impairment of bile flow.