To test the hypothesis that rat hepatocyte canalicular Cl-/HCO3/- exchange activity might be regulated by HCO3/-- or protein kinase-induced changes in the apical targeting of vesicles, isolated rat hepatocytes were cultured in the presence or absence of HCO3/-/CO2. Cl-/HCO3/- exchange activity increased in cells cultured in the presence of HCO3/-CO2 or when stimulated by dibutyryl cAMP. Both of these effects were blocked by either colchicine or the protein kinase C agonist phorbol 12,13-dibutyrate. Fluorescence and confocal microscopy, respectively, revealed increased pericanalicular-apical membrane localization of two canalicular markers, peanut agglutinin and a 110-kDa canalicular ecto-ATPase, when hepatocyte couplets were preincubated in HCO3/-/CO2-containing medium, an effect that was again blocked by colchicine. Dibutyryl cAMP also stimulated canalicular localization of the 110-kDa protein. These findings suggest that hepatocyte Cl-/HCO3/- exchange activity is regulated by HCO3/-/CO2 and by protein kinase A and protein kinase C agonists through microtubule-dependent targeting of vesicles containing this exchanger to the canalicular domain.
Benedetti, A., Strazzabosco, M., Ng, O., Boyer, J. (1994). Regulation of activity and apical targeting of the Cl-/HCO3- exchanger in rat hepatocytes. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 91(2), 792-796 [10.1073/pnas.91.2.792].
Regulation of activity and apical targeting of the Cl-/HCO3- exchanger in rat hepatocytes.
STRAZZABOSCO, MARIO;
1994
Abstract
To test the hypothesis that rat hepatocyte canalicular Cl-/HCO3/- exchange activity might be regulated by HCO3/-- or protein kinase-induced changes in the apical targeting of vesicles, isolated rat hepatocytes were cultured in the presence or absence of HCO3/-/CO2. Cl-/HCO3/- exchange activity increased in cells cultured in the presence of HCO3/-CO2 or when stimulated by dibutyryl cAMP. Both of these effects were blocked by either colchicine or the protein kinase C agonist phorbol 12,13-dibutyrate. Fluorescence and confocal microscopy, respectively, revealed increased pericanalicular-apical membrane localization of two canalicular markers, peanut agglutinin and a 110-kDa canalicular ecto-ATPase, when hepatocyte couplets were preincubated in HCO3/-/CO2-containing medium, an effect that was again blocked by colchicine. Dibutyryl cAMP also stimulated canalicular localization of the 110-kDa protein. These findings suggest that hepatocyte Cl-/HCO3/- exchange activity is regulated by HCO3/-/CO2 and by protein kinase A and protein kinase C agonists through microtubule-dependent targeting of vesicles containing this exchanger to the canalicular domain.
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