title: Bile canalicular contraction in the isolated hepatocyte doublet is related to an increase in cytosolic free calcium ion concentration.
abstract: Dynamic contractions of bile canaliculi have been observed in cultured doublet hepatocytes by means of time-lapse cinephotomicrography, and this contractile movement plays an important role in bile secretion. Although details of the mechanism are still unknown, the Ca2+-calmodulin system is believed to play a main role in this mechanism. In this study we measured the intracellular Ca2+ concentration of individual doublet hepatocytes using the Ca2+ indicator "fura 2" and microscopic fluorometry. We also observed the effects of A23187, norepinephrine and epinephrine on bile canalicular contraction and intracellular Ca2+ concentration. After loading 1 mumol/l fura 2 in doublet cells, we added A23187, epinephrine or norepinephrine and then measured the Ca2+ concentration in a given small area in the cytoplasm of individual doublet cell. A23187, norepinephrine and epinephrine caused a prompt increase of the intracellular Ca2+ concentration and also caused bile canalicular contraction. The present study indicates that the sudden increase of intracellular Ca2+ concentration causes bile canalicular contraction through the Ca2+-calmodulin system.
authors: Department of Medicine, Juntendo University, Tokyo, Japan.
authors: S
authors: S
authors: Watanabe
authors: M
authors: M
authors: Tomono
authors: M
authors: M
authors: Takeuchi
authors: T
authors: T
authors: Kitamura
authors: M
authors: M
authors: Hirose
authors: A
authors: A
authors: Miyazaki
authors: T
authors: T
authors: Namihisa
mesh_terms: D000818:Animals; D001648:Bile Canaliculi / Q000187:drug effects / Q000502:physiology*; D001653:Bile Ducts, Intrahepatic / Q000502:physiology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D008099:Liver / Q000166:cytology*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007473:Ion Channels; D000001:Calcimycin; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine