| Popis: |
We studied emptying and filling (contraction and excretion) of bile canaliculi (BC) in primary cultures of hepatocytes by morphometry. Primary cultures of hepatocytes obtained from 14-day-old rats were used after 48 h incubation. In order to measure the rate of canalicular filling, the canaliculi were first emptied by stimulating canalicular contraction of the liver cells with vasopressin (VP, 10 −8 M) for an hour. The filling rate was then measured by incubating the hepatocytes with the VP-free medium containing taurocholate (TC, 100 μM) and/or ouabain (OB, 1 mM) for an hour. Morphometric analysis showed that the canalicular lumen size (μm 2 ) responded to these treatments in a heterogenous way. That is, some of the BC emptied and others filled but the net effect of the change in canalicular luminal square area was predominantly either emptying or filling depending on the treatment. The total square area of the BC decreased on the average 17.5 ± 29.0% (mean ± SD) after treatment with VP. After removal of VP, the average μm 2 of the BC spontaneously increased by 9.8% over an hour. TC stimulated the filling of the BC but OB inhibited this filling process completely. The results are similar to those observed by others using perfused liver preparations where Na + /K + -ATPase activity and the bile acid load were shown to play an important role in canalicular excretion. Thus, this in vitro model of confluent hepatocytes served as a valid model for accessing in vitro hepatic function of the biliary excretory apparatus. |
