ANALYSIS BY CONFOCAL LASER-SCANNING MICROSCOPY IMAGING OF UNDILATED BILE CANALICULI F-ACTIN STAINING IN THE HEPATOCYTES OF HUMAN EXTRAHEPATIC CHOLESTATIC LIVER

Many studies have demonstrated the role of bile canalicular microfilam ents in bile secretion and bile flow. It is now admitted that modifica tion of bile canalicular network of microfilaments play a role in dysf unction of bile secretion observed in many cases of cholestasis. This work intends to study F-actin, a major component of microfilaments, in human hepatocytes in extrahepatic cholestatis. Normal and extrahepati c cholestatic liver were studied. F-actin was stained with fluorescent phallotoxin and quantified by using confocal laser scanning microscop y and an image analysis method. Mean specific fluorescence (MSF) of bi le canaliculi was measured. Since dilated and bile plugged canaliculi were rarely observed in cholestatic liver sections, only undilated bil e canaliculi were analysed. Bile canalicular MSF was significantly inc reased (p<0.05) in cholestatic hepatocytes (1.3 to 1.7 fold higher tha n in controls). These data demonstrate a pericanalicular thickening of F-actin microfilaments in human extrahepatic cholestatis, similar to that described in literature in many cases of human intrahepatic and e xtrahepatic cholestasis cases as well as in experimentally induced cho lestasis. However, further studies are needed to understand this incre ase in F-actin pericanalicular microfilaments in human extrahepatic ch olestasis.